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The Atkins diet is a low-carb diet, usually recommended for weight loss.

Proponents of this diet claim that you can lose weight while eating as much protein and fat as you want, as long as you avoid foods high in carbs.

In the past 12 or so years, over 20 studies have shown that low-carb diets without the need for calorie counting are effective for weight loss and can lead to various health improvements.

The Atkins diet was originally promoted by the physician Dr. Robert C. Atkins, who wrote a best-selling book about it in 1972.

Since then, the Atkins diet has been popular all over the world with many more books having been written.

The diet was originally considered unhealthy and demonized by the mainstream health authorities, mostly due to its high saturated fat content. However, new studies suggest that saturated fat is harmless (, ).

Since then, the diet has been studied thoroughly and shown to lead to more weight loss and greater improvements in blood sugar, "good" HDL cholesterol, triglycerides and other health markers than low-fat diets (, ).

Despite being high in fat, it does not raise "bad" LDL cholesterol on average, though this does happen in a subset of individuals ().

The main reason why low-carb diets are so effective for weight loss is that a reduction in carbs and increased protein intake lead to reduced appetite, making you eat fewer calories without having to think about it (, ).

You can read more about the health benefits of low-carb diets in this article.

The Atkins diet is split into 4 different phases:

Phase 1 (induction): Under 20 grams of carbs per day for 2 weeks. Eat high-fat, high-protein, with low-carb vegetables like leafy greens. This kick-starts the weight loss.

Phase 2 (balancing): Slowly add more nuts, low-carb vegetables and small amounts of fruit back to your diet.

Phase 3 (fine-tuning): When you're very close to your goal weight, add more carbs to your diet until weight loss slows down.

Phase 4 (maintenance): Here you can eat as many healthy carbs as your body can tolerate without regaining weight.

However, these phases are a bit complicated and may not be necessary. You should be able to lose weight and keep it off as long as you stick to the meal plan below.

Some people choose to skip the induction phase altogether and include plenty of vegetables and fruit from the start. This approach can be very effective as well.

Others prefer to just stay in the induction phase indefinitely. This is also known as a very low-carb ketogenic diet (keto).

You should avoid these foods on the Atkins diet:

Sugar: Soft drinks, fruit juices, cakes, candy, ice cream, etc.

Grains: Wheat, spelt, rye, barley, rice.

Trans fats: Usually found in processed foods with the word "hydrogenated" on the ingredients list.

"Diet" and "low-fat" foods: These are usually very high in sugar.

High-carb vegetables: Carrots, turnips, etc (induction only).

High-carb fruits: Bananas, apples, oranges, pears, grapes (induction only).

Starches: Potatoes, sweet potatoes (induction only).

Legumes: Lentils, beans, chickpeas, etc. (induction only).

You should base your diet around these healthy foods.

Meats: Beef, pork, lamb, chicken, bacon and others.

Fatty fish and seafood: Salmon, trout, sardines, etc.

Eggs: The healthiest eggs are omega-3 enriched or pastured.

Low-carb vegetables: Kale, spinach, broccoli, asparagus and others.

Full-fat dairy: Butter, cheese, cream, full-fat yogurt.

Nuts and seeds: Almonds, macadamia nuts, walnuts, sunflower seeds, etc.

Healthy fats: Extra virgin olive oil, coconut oil, avocados and avocado oil.

As long as you base your meals around a fatty protein source with vegetables or nuts and some healthy fats, you will lose weight. It's that simple.

Beverages

Here are some drinks that are acceptable on the Atkins diet.

Water: As always, water should be your go-to beverage.

Coffee: Many studies show that coffee is high in antioxidants and quite healthy.

Green tea: A very healthy beverage.

Alcohol is also fine in small amounts. Stick to dry wines with no added sugars and avoid high-carb drinks like beer.

There are many delicious foods you can eat on the Atkins diet.

This includes foods like bacon, heavy cream, cheese and dark chocolate.

Many of these are generally considered fattening because of the high fat and calorie content.

However, when you're on a low-carb diet, your body increases its use of fat as an energy source and suppresses your appetite, reducing the risk of overeating and weight gain.

If you'd like to know more, check out this article on 6 Indulgent Foods That Are Low-Carb Friendly.

Despite what you may have heard, the Atkins diet is quite flexible.

It's only during the two-week induction phase that you need to minimize your intake of carb sources.

After induction is over, you can slowly add back healthier carbs such as higher-carb vegetables, fruits, berries, potatoes, legumes and healthier grains like oats and rice.

However, chances are that you will need to stay moderately low-carb for life, even if you reach your weight loss goals.

If you start eating the same old foods again in the same amounts as before, you will gain back the weight. This is true of any weight loss diet.

It is possible to do the Atkins diet as a vegetarian (and even vegan), but difficult.

You can use soy-based foods for protein and eat plenty of nuts and seeds. Olive oil and coconut oil are excellent plant-based fat sources.

Lacto-ovo-vegetarians can also eat eggs, cheese, butter, heavy cream and other high-fat dairy foods.

This is a sample menu for one week on the Atkins diet.

It's suitable for the induction phase, but you should add more higher-carb vegetables and some fruits as you move on to the other phases.

Monday

Tuesday

Breakfast: Bacon and eggs.

Lunch: Leftover chicken and veggies from the night before.

Dinner: Bunless cheeseburger, with vegetables and butter.

Wednesday

Thursday

Friday

Saturday

Sunday

Make sure to include a variety of different vegetables in your diet.

For a few examples of healthy and satisfying low-carb meals, check out this article on 7 Healthy Low-Carb Meals in Under 10 Minutes.

Healthy Low-Carb Snacks

Most people feel that their appetite goes down on the Atkins diet.

They tend to feel more than satisfied with 3 meals per day (sometimes only 2).

However, if you feel hungry between meals, here are a few quick healthy snacks:

Leftovers.

A hard-boiled egg or two.

A piece of cheese.

A piece of meat.

A handful of nuts.

Some Greek yogurt.

Berries and whipped cream.

Baby carrots (careful during induction).

Fruits (after induction).

It's actually very easy to follow the Atkins diet at most restaurants.

1. Get extra vegetables instead of bread, potatoes or rice.

2. Order a meal based on fatty meat or fatty fish.

3. Get some extra sauce, butter or olive oil with your meal.

It's a good rule to shop at the perimeter of the store. This is usually where the whole foods are found.

Eating organic is not necessary, but always go for the least processed option that fits your budget.

Meats: Beef, chicken, lamb, pork, bacon.

Fatty fish: Salmon, trout, etc.

Shrimp and shellfish.

Dairy: Greek yogurt, heavy cream, butter, cheese.

Vegetables: Spinach, kale, lettuce, tomatoes, broccoli, cauliflower, asparagus, onions, etc.

Berries: Blueberries, strawberries, etc.

Nuts: Almonds, macadamia nuts, walnuts, hazelnuts, etc.

Seeds: Sunflower seeds, pumpkin seeds, etc.

Fruits: Apples, pears, oranges.

Coconut oil.

Olives.

Extra virgin olive oil.

Dark chocolate.

Avocados.

Condiments: Sea salt, pepper, turmeric, cinnamon, garlic, parsley, etc.

It's highly recommended to clear your pantry of all unhealthy foods and ingredients. This includes ice cream, sodas, breakfast cereals, breads, juices and baking ingredients like sugar and wheat flour.

If you're serious about the Atkins diet, consider buying or borrowing one of the Atkins books and simply get started as soon as possible.

That being said, the detailed guide in this article should contain everything you need to succeed. To create a printable version, click here.

For recipe ideas, check out this article on 101 Healthy Low-Carb Recipes That Taste Incredible

At the end of the day, the Atkins diet is a healthy and effective way to lose weight. You won't be disappointed.

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The Atkins Diet: Everything You Need to Know

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We include products we think are useful for our readers. If you buy through links on this page, we may earn a small commission. Here's our process. The Atkins diet is a low-carb diet, usually recommended for weight loss.

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Helen Truby, senior lecturer in nutrition and dietetics, ¹ Sue Baic, lecturer in nutrition, ² Anne deLooy, professor of dietetics, ³ Kenneth R Fox, professor of exercise science, ² M Barbara E Livingstone, professor of nutrition, ⁴ Catherine M Logan, PhD student, ⁴ Ian A Macdonald, professor, ⁵ Linda M Morgan, professor of nutritional endocrinology, ¹ Moira A Taylor, lecturer in nutrition and dietetics, ⁵ and D Joe Millward, professor of human nutrition ¹

Abstract

Objective To compare the effectiveness of four commercial weight loss diets available to adults in the United Kingdom.

Design Six month multicentre randomised unblinded controlled trial.

Setting Community based sample of otherwise healthy overweight and obese adults.

Interventions Dr Atkins' new diet revolution, Slim-Fast plan, Weight Watchers pure points programme, and Rosemary Conley's eat yourself slim diet and fitness plan.

Main outcome measures Weight and body fat changes over six months.

Results All diets resulted in significant loss of body fat and weight over six months. Groups did not differ significantly but loss of body fat and weight was greater in all groups compared with the control group. In an intention to treat analysis, average weight loss was 5.9 kg and average fat loss was 4.4 kg over six months. The Atkins diet resulted in significantly higher weight loss during the first four weeks, but by the end was no more or less effective than the other diets.

Conclusions Clinically useful weight loss and fat loss can be achieved in adults who are motivated to follow commercial diets for a substantial period. Given the limited resources for weight management in the NHS, healthcare practitioners should discuss with their patients programmes known to be effective.

Trial registration Clinical trials NCT00327821.

Introduction

The prevalence of obesity and its comorbidities is increasing in the United Kingdom. Over half of British adults are now overweight, and half of these people will probably become obese. The estimated cost of obesity is £0.5bn (€0.7bn; $0.9bn) each year to the NHS and £2bn each year to the wider economy.

Most adults in the United States diet at some time, and trends in the UK are similar.⁻ Long term success rates tend to be poor, with 50% of weight loss being regained within one year.

With a market estimated to be worth £11.2bn by 2007, it is not surprising that the commercial sector has shown a keen interest in weight loss programmes. Weight Watchers, the market leader, claims to have one million members (P Hunt, personal communication, 2005). Self help books that provide weight loss strategies are often best sellers- Dr Atkins' New Diet Revolution has sold more than 10 million copies. Although commercial diets provide consumers with a plethora of choice, data on their comparative efficacy are limited.

Our study compared four popular commercial weight loss programmes with a control group. The diets-representative of the main approaches to weight management in the UK today-were the Slim-Fast plan (a meal replacement approach), Weight Watchers pure points programme (an energy controlled diet with weekly group meetings), Dr Atkins' new diet revolution (a self monitored low carbohydrate eating plan), and Rosemary Conley's eat yourself slim diet and fitness plan (a low fat diet and a weekly group exercise class). We report the changes in weight and body fat over the six month study and describe dieting behaviour and weight change in the participants at 12 months.

Methods

The trial was an unblinded randomised controlled parallel dietary intervention study with a delayed treatment control group conducted at five regional centres (Surrey University, Bristol University, Nottingham University, Ulster (Coleraine) University, and Queen Margaret University College, Edinburgh).

Recruitment strategy

We identified potential participants via a BBC advertising campaign (television and other forms of media). Participants were chosen from people who lived within 30 miles of a test centre, were aged between 18 and 65, and had a self reported body mass index between 27 and 40. Volunteers who fulfilled these preliminary inclusion criteria contacted their general practitioner for confirmation that they were eligible. Exclusion criteria were coronary heart disease; type 1 or type 2 diabetes; renal, liver, or respiratory failure; gout; obesity with known cause (Cushing's disease, hypothyroidism); previous gastric or weight loss surgery; clinical depression; eating disorders; drug or alcohol misuse; any malabsorptive state (including lactose intolerance); taking lipid lowering or anti-hypertensive drugs; taking any drugs (including orlistat and sibutramine) for weight loss; being treated for cancer; and being pregnant or breastfeeding. Participants gave full informed consent. Three hundred people returned the necessary documentation to enter baseline testing by the start date of the study (July 2002).

Protocol assignment

We estimated that 60 initial participants (44 completers) were needed per treatment group (allowing for a 25% dropout rate) for an 80% chance of identifying a true difference of 4 kg of body weight loss (3 kg body fat), with a significance level of 5%. Thus, each of the five test centres aimed to recruit 60 participants (12 for each diet group; total sample size of 300). Participants took all baseline tests before randomisation and each centre started the study within six weeks of the start date. Seven participants were subsequently excluded (). At each test centre, we stratified participants by sex and allocated them to a group using random number generation. Body mass index and age did not differ between groups or between centres.

It was not possible to blind the participants to the diet regimen and we did not attempt to blind the investigators during the study or data analysis.

Providing dietary programmes to participants

For the group based programmes (Weight Watchers and Rosemary Conley), participants attended the most convenient class and we reimbursed the costs of joining and attending one class each week. Both parent companies signed a contract committing to the provision of standard care. For Slim-Fast, we reimbursed the cost of up to two meal replacements each day and provided a copy of the Slim-Fast support pack. We gave participants in the Atkins group a copy of Dr Atkins' New Diet Revolution. We asked the members of the control group to maintain their current diet and exercise pattern and offered them any of the diets for six months at the end of study (free of charge). All participants could claim reimbursement of travel costs.

Study protocol and monitoring

Measures at baseline, two months, and six months included weight, height, waist circumference, blood pressure, and fasting blood and body fat by whole body dual x ray absorptiometry. We excluded the absorptiometry data of four participants from all analyses because of errors at baseline. Monthly test centre measurements recorded weight in light clothing, blood pressure, and waist circumference. We monitored renal function in the Atkins group by urea, electrolytes, and cystatin C, and these measures remained within the reference ranges. Participants completed a seven day diet and activity diary at baseline, eight weeks, and 24 weeks. We gave no dietary or exercise advice so as not to compromise the study. When we analysed the food diaries at two months we found that some of the participants on the Atkins diet were not taking supplements of micronutrients as advised in the book. Therefore, from week 10 we offered free daily supplements of multivitamins. All participants who withdrew completed a short exit questionnaire. At 12 months, we recorded the weight and dieting behaviour from six to 12 months of all participants still willing to attend test centres.

Statistical analysis

The primary analysis was on an intention to treat basis, with baseline values carried forward to replace missing values (one participant was not used in this analysis as she withdrew because of pregnancy). A secondary analysis focused on the outcomes of these dietary approaches in the most motivated subjects who provided complete data (baseline, two months, and six months). Analysis of variance showed that the test centre did not affect total weight loss in participants who completed. Attrition rates did not differ between centres, so we analysed data from all participants together. Baseline weight correlated with total weight loss ( r = 0.33, P < 0.001) and was therefore used as a covariate in the analysis of weight loss over time, which uses repeated measures analysis of covariance. In the intention to treat analysis, we used ANOVA to examine differences between groups; where ANOVA indicated a significant group effect, we performed post hoc pairwise testing with Tukey's HSD (honestly significantly different) test. Before parametric testing, we assessed homogeneity of variance with Levene's statistic and tested for normal distribution; we used Welch's F statistic if variance of the dependent variable was not equal across groups. We analysed differences between participants who completed and withdrew with t tests for continuous variables (such as age) and χ ² for categorical variables (such as sex and diet group).

Results

shows the baseline demographics and anthropometric measures. The mean time spent on the diet was 24.3 (SD 1.56) weeks and did not differ between diet groups ( F = 2.0, P = 0.12).

Table 1

Weight and fat loss

Monthly weight loss by using all available data () was high initially but then slowed. Mean weight loss was significantly higher in the Atkins group than in the other diet groups during the first four weeks ( F = 6.9, df = 3, P < 0.001): Atkins 4.4 kg (SD 2.45, range 13.5 to 0.3 kg), Weight Watchers 2.86 kg (2.23, 12.9 to - 0.9 kg), Slim-Fast 2.68 kg (2.33, 9.4 to - 1.8 kg), and Rosemary Conley 3.17 kg (2.02, 8.1 to - 2.0 kg). At other time points, mean weight loss did not vary significantly between the diet groups ().

Table 2

Loss of body fat showed similar patterns (). In the first two months, the greatest loss of body fat was seen in the Atkins group; this loss was not significantly different from that seen in the Weight Watchers or Rosemary Conley groups, but it was significantly greater than that seen in the Slim-Fast group. Fat loss was significantly greater in all four diet groups than in the control group. Between two and six months, fat loss (kg and percentage) slowed down, and the diets groups did not differ significantly. Between baseline and six months fat loss did not differ between diet groups, but fat loss in all diet groups was significantly greater than in the control group. All diets resulted in a reduction in waist circumference. Waist reduction (at six months) was highly correlated with total weight loss ( r = 0.81, P < 0.001) and moderately correlated with percentage of body fat lost ( r = 0.64, P < 0.001).

Cardiac risk factors

We found few significant differences in cardiac risk factors between the diets groups and the control group (). Initially, the fall in systolic pressure in the Atkins group was significantly greater than in the Slim-Fast group but not the other groups, probably because of the relatively greater initial weight loss in the Atkins group. Regression analysis showed that total weight loss over time had the greatest influence on systolic and diastolic pressure (adjusted R ² 0.61 for change in systolic pressure and 0.79 for change in diastolic pressure).

Table 3

Glucose concentrations fell slightly over time; only in the Weight Watchers group was fasting glucose significantly lower than in the control group. In the first two months, a significant but small drop in total cholesterol was seen in all diet groups except for the Atkins group. By six months, cholesterol had fallen significantly compared with the control group only in the Weight Watchers group (by 0.55 mmol/l).

Analysis of completers

A secondary analysis of data from participants who completed the trial shows the range of weight lost by these highly motivated participants, who probably adhered most strongly to the randomly allocated diets. shows the range of total weight lost; some participants lost more than 25 kg over the six month study period, whereas others gained weight ().

After six months all diets resulted in a clinically useful mean reduction in percentage body weight: Rosemary Conley 9.9% (SD 5.6%), Weight Watchers 9.0% (5.6%), Atkins 8.9% (5.6%), and Slim-Fast 6.8% (5.3%); no significant differences were seen between the diets but all were more successful than no diet (controls gained 0.95%, 3.3%). The proportion of participants who completed the trial and lost at least 10% of their body weight at six months was 46% for the Rosemary Conley group, 45% for the Atkins group, 36% for the Weight Watchers group, and 21% for the Slim-Fast group. These losses were achieved despite the random allocation of diets.

Compliance with the diets

Reported attendance at slimming clubs was similar at two months (Rosemary Conley 79%, Weight Watchers 66%) and six months (47%, 47%). Slim-Fast recommends 14 meal replacements each week; participants reported 10 each week at two months and eight at six months. With the Atkins diet, reported portions of carbohydrate foods fell from 40 each day at baseline to five at two months and seven at six months.

Withdrawal

Eighty three (28%) participants had withdrawn by six months (); 53 (64% of the total number) had withdrawn by week 8, and at this time only seven (8%) participants who withdrew had lost more than 5% of their body weight compared with 53 (25%) who completed the trial. Older participants were significantly more likely to complete than younger ones (mean age 41.6 (9.9) v 36.8 (10.4); t = - 3.7, P < 0.001; 95% confidence interval 2.3 to 7.4). No differences in diet, centre, or sex were found between participants who completed or withdrew. Withdrawal in the control group (21; 35%) was mostly because participants did not wish to delay dieting.

Table 4

Follow-up at 12 months

At 12 months, 158 participants (54% of the original sample) returned data; 29 had originally been allocated to the Atkins diet, 33 to Weight Watchers, 33 to Slim-Fast, 35 to Rosemary Conley, and 28 to the control group. Dieting behaviour had changed considerably: only 58 (45%) were still keeping to their originally allocated diets (nine to Atkins, 20 to Weight Watchers, nine to Slim-Fast, 20 to Rosemary Conley). Twenty five (19%) had swapped dietary programmes and 47 (36%) were following their own diet or exercise plan. More participants in the unsupported programmes (Atkins diet and Slim-Fast) withdrew than in the supported programmes (χ ² = 8.34, df = 3.0, P = 0.04). Participants in the control group who had switched to dieting (mean weight loss 6.37, SD 4.5 kg) also preferred group based approaches because just over half chose Weight Watchers.

Because so many participants changed diets (25% of men and 29% of women), we also analysed weight loss in participants who had maintained the diet to which they were initially allocated (). Statistical analysis is limited by sample size but indicates that weight rebound after the initial six months was higher in the unsupported programmes; however, all diets resulted in a clinically useful weight loss of around 10% after 12 months in participants who had persisted with the diet allocated.

Table 5

Discussion

Clinically beneficial weight loss is possible through commercially available strategies, and reduced blood pressure and waist circumference accompany weight loss. The four different approaches were equally effective after six months. Reductions in weight and body fat were seen with the Atkins diet within the first eight weeks of dieting, so that the large weight changes seen with low carbohydrate diets are not caused by loss of body water alone. The Atkins diet had no detrimental effects on total cholesterol concentrations or renal function, although the overall safety of the diet was not tested.

The range of absolute weight loss in participants who completed the study was wide. Importantly, we did not try to standardise energy intake across the groups, so that the effects reflect the participants' interpretation of and compliance with the diet allocated. However, the mean absolute weight loss of around 8 kg is comparable to other studies. Compliance with each diet varied greatly. Weight can be lost only by a sustained negative balance of energy, so the degree of adherence to a diet will predict success or failure if activity levels remain constant. More information is needed to enable health professionals to decide which dietary approach may suit their patients. Currently, we cannot predict the dietary approach best suited to each person to lose weight and maintain weight loss in the longer term, but it is clear that "one size does not fit all."

Our study was used to make the BBC series on diet trials, which featured a small number of people. Since motivation to meet goal weights and patients' expectations of weight loss are key determinants of success, participants may have been influenced by the media interest. Overall, around 5% of participants were featured in the television programmes, and most participants knew that they would not be filmed within the first few weeks. Excluding data from the 15 filmed participants had no effect on the overall statistical outcomes shown in this study. The withdrawal rate was comparable to other longitudinal studies of weight loss.⁻

No dietary differences were apparent at six months, but behaviour from six to 12 months points towards an advantage of programmes based on group support. The need for a "quick fix" and the relative lack of interest that people show in achieving modest weight loss contribute to lack of adherence to most diets in the long term. People who had kept to their allocated diet lost about 10% of their weight, despite some weight rebound, but some regression to the mean effect was seen. These results provide information on the "best effect" that the most highly motivated subjects may hope to achieve over one year.

In conclusion, commercial weight loss programmes can help people with uncomplicated obesity. Our study provides data on how much weight patients can expect to lose by dieting, and these data could help practitioners in managing patients' some-times unrealistic expectations of weight loss targets. The benefits to health of modest weight loss and maintaining that loss over long periods need to be emphasised.
What is already known about this topic
The prevalence of obesity and overweight with its subsequent comorbidities is growing in the UK

Commercial diets are an increasingly popular option for weight management
What this study adds
The comparative efficacy of four commercial diets was similar

The health benefits associated with a modest loss of weight (5-10% body weight) can be gained by people following a range of dietary regimens for six months with little support from health professionals

Notes

Contributors: HT was the principal investigator and is guarantor. She contributed to the study design, data analysis, interpretation, drafting, and writing of the paper. DJM and LMM contributed to the study design, data analysis, interpretation, drafting, and writing of the paper. KRF contributed to the study design, interpretation, reporting, and critical review of paper. SB contributed to study execution, data collection, and critical review of the paper. IAM, MAT, MBEL, CML, and AdeL contributed to the study planning, interpretation, reporting, and critical review of the paper. Thanks to David Lovell for statistical advice; Manana Stanley, Rebecca Hiscutt, and Anne Herriot for planning, study execution, and data collection; Monique Raats and Richard Shepherd for study planning; Kathryn Hart, Rachel Barratt, Karen Sargent, Sarah Jones, Julie Littlewood, Sujata Dissanayake, Elizabeth Simpson, and Michelle Hazell for data collection; Mark Davis for study design and data collection; Katherine Collings for planning, study execution, and data collection; Paula J Robson, Julie MW Wallace, Maxine P Bonham, and Laura Nichol for study execution and data collection; Susan Jebb for study design; and Kirsten Rennie for sample size determination.

Competing interests: KRF receives consulting fees for serving on the scientific advisory panel of Slimming World, a company that offers a support service for weight loss. This company was not involved in this trial but as it is similar to Rosemary Conley and Weight Watchers, the conclusions may have implications for the company.

Funding: The study was sponsored by the BBC. The BBC had no role in the study design; collection, analysis, or interpretation of data; or report writing.

Ethical approval: South East multicentre research ethics committee, approval number MREC 01/01/44. Local ethics committee approval was also obtained at each centre.

References

1. Department of Health. White paper on public health. Saving lives: our healthier nation. London: Stationery Office, 1999.

2. Royal College of Physicians. Storing up problems: the medical case for a slimmer nation. London: RCP, 2004. [ PMC free article] [ PubMed]

7. Perri MG. The maintenance of treatment effects in the long term management of obesity. Clin Psychol Sci Pract 1998;5: 526-43. [ Google Scholar]

8. Atkins R. Dr Atkins' new diet revolution. South Dakota: Vermillion, 1999.

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Randomised controlled trial of four commercial weight loss programmes in the UK: initial findings from the BBC "diet trials"

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Helen Truby, senior lecturer in nutrition and dietetics, 1 Sue Baic, lecturer in nutrition, 2 Anne deLooy, professor of dietetics, 3 Kenneth R Fox, professor of exercise science, 2 M Barbara E Livingstone, professor of nutrition, 4 Catherine M Logan, PhD student, 4 Ian A Macdonald, professor, 5 Linda M Morgan, professor of nutritional endocrinology, 1 Moira A Taylor, lecturer in nutrition and dietetics, 5 and D Joe Millward, professor of human nutrition 1 Objective To compare the effectiveness of four commercial weight loss diets available to adults in the United Kingdom.

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https://www.veganlifestylecoach.com/diet-alert-atkins

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Atkins Diet Alert

Dear Reader:

Welcome to AtkinsDietAlert.org, a resource for physicians and laypeople with questions and concerns about high-protein diets.

This Web site offers the latest news and information about these diets, as well as a registry where dieters can record any health complications they've experienced.

AtkinsDietAlert.org is brought to you by the Physicians Committee for Responsible Medicine, a leading advocate for preventive medicine, especially good nutrition. PCRM has been speaking out about the dangers of high-protein diets since its founding in 1985. Studies show that meat-heavy, high-protein eating patterns are, over the long run, linked to osteoporosis, heart disease, colon cancer, and renal disease, and pose particular dangers for people with diabetes.

Given the seriousness of these health risks, and the strength of the scientific evidence currently available, PCRM hopes this Web site will encourage people to be wary of high-protein diets and to choose healthier options. PCRM is also concerned about possible legal liability for doctors who prescribe these diets.

If you are a health care practitioner, please read our physician advisory and consider recommending against high-protein diets. If you are a layperson on one of the high-protein diets, please read our consumer advisory and consider joining our registry. It will only take a few minutes of your time, but it could provide important information on diet-related health risks.

Thanks for visiting. We wish you the very best of health.

Sincerely,

Neal D. Barnard, M.D.
President
Physicians Committee for Responsible Medicine

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Dear Reader: Welcome to AtkinsDietAlert.org, a resource for physicians and laypeople with questions and concerns about high-protein diets. This Web site offers the latest news and information about these diets, as well as a registry where dieters can record any health complications they've experienced.

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Helen Truby, senior lecturer in nutrition and dietetics, ¹ Sue Baic, lecturer in nutrition, ² Anne deLooy, professor of dietetics, ³ Kenneth R Fox, professor of exercise science, ² M Barbara E Livingstone, professor of nutrition, ⁴ Catherine M Logan, PhD student, ⁴ Ian A Macdonald, professor, ⁵ Linda M Morgan, professor of nutritional endocrinology, ¹ Moira A Taylor, lecturer in nutrition and dietetics, ⁵ and D Joe Millward, professor of human nutrition ¹

Abstract

Objective To compare the effectiveness of four commercial weight loss diets available to adults in the United Kingdom.

Design Six month multicentre randomised unblinded controlled trial.

Setting Community based sample of otherwise healthy overweight and obese adults.

Interventions Dr Atkins' new diet revolution, Slim-Fast plan, Weight Watchers pure points programme, and Rosemary Conley's eat yourself slim diet and fitness plan.

Main outcome measures Weight and body fat changes over six months.

Results All diets resulted in significant loss of body fat and weight over six months. Groups did not differ significantly but loss of body fat and weight was greater in all groups compared with the control group. In an intention to treat analysis, average weight loss was 5.9 kg and average fat loss was 4.4 kg over six months. The Atkins diet resulted in significantly higher weight loss during the first four weeks, but by the end was no more or less effective than the other diets.

Conclusions Clinically useful weight loss and fat loss can be achieved in adults who are motivated to follow commercial diets for a substantial period. Given the limited resources for weight management in the NHS, healthcare practitioners should discuss with their patients programmes known to be effective.

Trial registration Clinical trials NCT00327821.

Introduction

The prevalence of obesity and its comorbidities is increasing in the United Kingdom. Over half of British adults are now overweight, and half of these people will probably become obese. The estimated cost of obesity is £0.5bn (€0.7bn; $0.9bn) each year to the NHS and £2bn each year to the wider economy.

Most adults in the United States diet at some time, and trends in the UK are similar.⁻ Long term success rates tend to be poor, with 50% of weight loss being regained within one year.

With a market estimated to be worth £11.2bn by 2007, it is not surprising that the commercial sector has shown a keen interest in weight loss programmes. Weight Watchers, the market leader, claims to have one million members (P Hunt, personal communication, 2005). Self help books that provide weight loss strategies are often best sellers- Dr Atkins' New Diet Revolution has sold more than 10 million copies. Although commercial diets provide consumers with a plethora of choice, data on their comparative efficacy are limited.

Our study compared four popular commercial weight loss programmes with a control group. The diets-representative of the main approaches to weight management in the UK today-were the Slim-Fast plan (a meal replacement approach), Weight Watchers pure points programme (an energy controlled diet with weekly group meetings), Dr Atkins' new diet revolution (a self monitored low carbohydrate eating plan), and Rosemary Conley's eat yourself slim diet and fitness plan (a low fat diet and a weekly group exercise class). We report the changes in weight and body fat over the six month study and describe dieting behaviour and weight change in the participants at 12 months.

Methods

The trial was an unblinded randomised controlled parallel dietary intervention study with a delayed treatment control group conducted at five regional centres (Surrey University, Bristol University, Nottingham University, Ulster (Coleraine) University, and Queen Margaret University College, Edinburgh).

Recruitment strategy

We identified potential participants via a BBC advertising campaign (television and other forms of media). Participants were chosen from people who lived within 30 miles of a test centre, were aged between 18 and 65, and had a self reported body mass index between 27 and 40. Volunteers who fulfilled these preliminary inclusion criteria contacted their general practitioner for confirmation that they were eligible. Exclusion criteria were coronary heart disease; type 1 or type 2 diabetes; renal, liver, or respiratory failure; gout; obesity with known cause (Cushing's disease, hypothyroidism); previous gastric or weight loss surgery; clinical depression; eating disorders; drug or alcohol misuse; any malabsorptive state (including lactose intolerance); taking lipid lowering or anti-hypertensive drugs; taking any drugs (including orlistat and sibutramine) for weight loss; being treated for cancer; and being pregnant or breastfeeding. Participants gave full informed consent. Three hundred people returned the necessary documentation to enter baseline testing by the start date of the study (July 2002).

Protocol assignment

We estimated that 60 initial participants (44 completers) were needed per treatment group (allowing for a 25% dropout rate) for an 80% chance of identifying a true difference of 4 kg of body weight loss (3 kg body fat), with a significance level of 5%. Thus, each of the five test centres aimed to recruit 60 participants (12 for each diet group; total sample size of 300). Participants took all baseline tests before randomisation and each centre started the study within six weeks of the start date. Seven participants were subsequently excluded (). At each test centre, we stratified participants by sex and allocated them to a group using random number generation. Body mass index and age did not differ between groups or between centres.

It was not possible to blind the participants to the diet regimen and we did not attempt to blind the investigators during the study or data analysis.

Providing dietary programmes to participants

For the group based programmes (Weight Watchers and Rosemary Conley), participants attended the most convenient class and we reimbursed the costs of joining and attending one class each week. Both parent companies signed a contract committing to the provision of standard care. For Slim-Fast, we reimbursed the cost of up to two meal replacements each day and provided a copy of the Slim-Fast support pack. We gave participants in the Atkins group a copy of Dr Atkins' New Diet Revolution. We asked the members of the control group to maintain their current diet and exercise pattern and offered them any of the diets for six months at the end of study (free of charge). All participants could claim reimbursement of travel costs.

Study protocol and monitoring

Measures at baseline, two months, and six months included weight, height, waist circumference, blood pressure, and fasting blood and body fat by whole body dual x ray absorptiometry. We excluded the absorptiometry data of four participants from all analyses because of errors at baseline. Monthly test centre measurements recorded weight in light clothing, blood pressure, and waist circumference. We monitored renal function in the Atkins group by urea, electrolytes, and cystatin C, and these measures remained within the reference ranges. Participants completed a seven day diet and activity diary at baseline, eight weeks, and 24 weeks. We gave no dietary or exercise advice so as not to compromise the study. When we analysed the food diaries at two months we found that some of the participants on the Atkins diet were not taking supplements of micronutrients as advised in the book. Therefore, from week 10 we offered free daily supplements of multivitamins. All participants who withdrew completed a short exit questionnaire. At 12 months, we recorded the weight and dieting behaviour from six to 12 months of all participants still willing to attend test centres.

Statistical analysis

The primary analysis was on an intention to treat basis, with baseline values carried forward to replace missing values (one participant was not used in this analysis as she withdrew because of pregnancy). A secondary analysis focused on the outcomes of these dietary approaches in the most motivated subjects who provided complete data (baseline, two months, and six months). Analysis of variance showed that the test centre did not affect total weight loss in participants who completed. Attrition rates did not differ between centres, so we analysed data from all participants together. Baseline weight correlated with total weight loss ( r = 0.33, P < 0.001) and was therefore used as a covariate in the analysis of weight loss over time, which uses repeated measures analysis of covariance. In the intention to treat analysis, we used ANOVA to examine differences between groups; where ANOVA indicated a significant group effect, we performed post hoc pairwise testing with Tukey's HSD (honestly significantly different) test. Before parametric testing, we assessed homogeneity of variance with Levene's statistic and tested for normal distribution; we used Welch's F statistic if variance of the dependent variable was not equal across groups. We analysed differences between participants who completed and withdrew with t tests for continuous variables (such as age) and χ ² for categorical variables (such as sex and diet group).

Results

shows the baseline demographics and anthropometric measures. The mean time spent on the diet was 24.3 (SD 1.56) weeks and did not differ between diet groups ( F = 2.0, P = 0.12).

Table 1

Weight and fat loss

Monthly weight loss by using all available data () was high initially but then slowed. Mean weight loss was significantly higher in the Atkins group than in the other diet groups during the first four weeks ( F = 6.9, df = 3, P < 0.001): Atkins 4.4 kg (SD 2.45, range 13.5 to 0.3 kg), Weight Watchers 2.86 kg (2.23, 12.9 to - 0.9 kg), Slim-Fast 2.68 kg (2.33, 9.4 to - 1.8 kg), and Rosemary Conley 3.17 kg (2.02, 8.1 to - 2.0 kg). At other time points, mean weight loss did not vary significantly between the diet groups ().

Table 2

Loss of body fat showed similar patterns (). In the first two months, the greatest loss of body fat was seen in the Atkins group; this loss was not significantly different from that seen in the Weight Watchers or Rosemary Conley groups, but it was significantly greater than that seen in the Slim-Fast group. Fat loss was significantly greater in all four diet groups than in the control group. Between two and six months, fat loss (kg and percentage) slowed down, and the diets groups did not differ significantly. Between baseline and six months fat loss did not differ between diet groups, but fat loss in all diet groups was significantly greater than in the control group. All diets resulted in a reduction in waist circumference. Waist reduction (at six months) was highly correlated with total weight loss ( r = 0.81, P < 0.001) and moderately correlated with percentage of body fat lost ( r = 0.64, P < 0.001).

Cardiac risk factors

We found few significant differences in cardiac risk factors between the diets groups and the control group (). Initially, the fall in systolic pressure in the Atkins group was significantly greater than in the Slim-Fast group but not the other groups, probably because of the relatively greater initial weight loss in the Atkins group. Regression analysis showed that total weight loss over time had the greatest influence on systolic and diastolic pressure (adjusted R ² 0.61 for change in systolic pressure and 0.79 for change in diastolic pressure).

Table 3

Glucose concentrations fell slightly over time; only in the Weight Watchers group was fasting glucose significantly lower than in the control group. In the first two months, a significant but small drop in total cholesterol was seen in all diet groups except for the Atkins group. By six months, cholesterol had fallen significantly compared with the control group only in the Weight Watchers group (by 0.55 mmol/l).

Analysis of completers

A secondary analysis of data from participants who completed the trial shows the range of weight lost by these highly motivated participants, who probably adhered most strongly to the randomly allocated diets. shows the range of total weight lost; some participants lost more than 25 kg over the six month study period, whereas others gained weight ().

After six months all diets resulted in a clinically useful mean reduction in percentage body weight: Rosemary Conley 9.9% (SD 5.6%), Weight Watchers 9.0% (5.6%), Atkins 8.9% (5.6%), and Slim-Fast 6.8% (5.3%); no significant differences were seen between the diets but all were more successful than no diet (controls gained 0.95%, 3.3%). The proportion of participants who completed the trial and lost at least 10% of their body weight at six months was 46% for the Rosemary Conley group, 45% for the Atkins group, 36% for the Weight Watchers group, and 21% for the Slim-Fast group. These losses were achieved despite the random allocation of diets.

Compliance with the diets

Reported attendance at slimming clubs was similar at two months (Rosemary Conley 79%, Weight Watchers 66%) and six months (47%, 47%). Slim-Fast recommends 14 meal replacements each week; participants reported 10 each week at two months and eight at six months. With the Atkins diet, reported portions of carbohydrate foods fell from 40 each day at baseline to five at two months and seven at six months.

Withdrawal

Eighty three (28%) participants had withdrawn by six months (); 53 (64% of the total number) had withdrawn by week 8, and at this time only seven (8%) participants who withdrew had lost more than 5% of their body weight compared with 53 (25%) who completed the trial. Older participants were significantly more likely to complete than younger ones (mean age 41.6 (9.9) v 36.8 (10.4); t = - 3.7, P < 0.001; 95% confidence interval 2.3 to 7.4). No differences in diet, centre, or sex were found between participants who completed or withdrew. Withdrawal in the control group (21; 35%) was mostly because participants did not wish to delay dieting.

Table 4

Follow-up at 12 months

At 12 months, 158 participants (54% of the original sample) returned data; 29 had originally been allocated to the Atkins diet, 33 to Weight Watchers, 33 to Slim-Fast, 35 to Rosemary Conley, and 28 to the control group. Dieting behaviour had changed considerably: only 58 (45%) were still keeping to their originally allocated diets (nine to Atkins, 20 to Weight Watchers, nine to Slim-Fast, 20 to Rosemary Conley). Twenty five (19%) had swapped dietary programmes and 47 (36%) were following their own diet or exercise plan. More participants in the unsupported programmes (Atkins diet and Slim-Fast) withdrew than in the supported programmes (χ ² = 8.34, df = 3.0, P = 0.04). Participants in the control group who had switched to dieting (mean weight loss 6.37, SD 4.5 kg) also preferred group based approaches because just over half chose Weight Watchers.

Because so many participants changed diets (25% of men and 29% of women), we also analysed weight loss in participants who had maintained the diet to which they were initially allocated (). Statistical analysis is limited by sample size but indicates that weight rebound after the initial six months was higher in the unsupported programmes; however, all diets resulted in a clinically useful weight loss of around 10% after 12 months in participants who had persisted with the diet allocated.

Table 5

Discussion

Clinically beneficial weight loss is possible through commercially available strategies, and reduced blood pressure and waist circumference accompany weight loss. The four different approaches were equally effective after six months. Reductions in weight and body fat were seen with the Atkins diet within the first eight weeks of dieting, so that the large weight changes seen with low carbohydrate diets are not caused by loss of body water alone. The Atkins diet had no detrimental effects on total cholesterol concentrations or renal function, although the overall safety of the diet was not tested.

The range of absolute weight loss in participants who completed the study was wide. Importantly, we did not try to standardise energy intake across the groups, so that the effects reflect the participants' interpretation of and compliance with the diet allocated. However, the mean absolute weight loss of around 8 kg is comparable to other studies. Compliance with each diet varied greatly. Weight can be lost only by a sustained negative balance of energy, so the degree of adherence to a diet will predict success or failure if activity levels remain constant. More information is needed to enable health professionals to decide which dietary approach may suit their patients. Currently, we cannot predict the dietary approach best suited to each person to lose weight and maintain weight loss in the longer term, but it is clear that "one size does not fit all."

Our study was used to make the BBC series on diet trials, which featured a small number of people. Since motivation to meet goal weights and patients' expectations of weight loss are key determinants of success, participants may have been influenced by the media interest. Overall, around 5% of participants were featured in the television programmes, and most participants knew that they would not be filmed within the first few weeks. Excluding data from the 15 filmed participants had no effect on the overall statistical outcomes shown in this study. The withdrawal rate was comparable to other longitudinal studies of weight loss.⁻

No dietary differences were apparent at six months, but behaviour from six to 12 months points towards an advantage of programmes based on group support. The need for a "quick fix" and the relative lack of interest that people show in achieving modest weight loss contribute to lack of adherence to most diets in the long term. People who had kept to their allocated diet lost about 10% of their weight, despite some weight rebound, but some regression to the mean effect was seen. These results provide information on the "best effect" that the most highly motivated subjects may hope to achieve over one year.

In conclusion, commercial weight loss programmes can help people with uncomplicated obesity. Our study provides data on how much weight patients can expect to lose by dieting, and these data could help practitioners in managing patients' some-times unrealistic expectations of weight loss targets. The benefits to health of modest weight loss and maintaining that loss over long periods need to be emphasised.
What is already known about this topic
The prevalence of obesity and overweight with its subsequent comorbidities is growing in the UK

Commercial diets are an increasingly popular option for weight management
What this study adds
The comparative efficacy of four commercial diets was similar

The health benefits associated with a modest loss of weight (5-10% body weight) can be gained by people following a range of dietary regimens for six months with little support from health professionals

Notes

Contributors: HT was the principal investigator and is guarantor. She contributed to the study design, data analysis, interpretation, drafting, and writing of the paper. DJM and LMM contributed to the study design, data analysis, interpretation, drafting, and writing of the paper. KRF contributed to the study design, interpretation, reporting, and critical review of paper. SB contributed to study execution, data collection, and critical review of the paper. IAM, MAT, MBEL, CML, and AdeL contributed to the study planning, interpretation, reporting, and critical review of the paper. Thanks to David Lovell for statistical advice; Manana Stanley, Rebecca Hiscutt, and Anne Herriot for planning, study execution, and data collection; Monique Raats and Richard Shepherd for study planning; Kathryn Hart, Rachel Barratt, Karen Sargent, Sarah Jones, Julie Littlewood, Sujata Dissanayake, Elizabeth Simpson, and Michelle Hazell for data collection; Mark Davis for study design and data collection; Katherine Collings for planning, study execution, and data collection; Paula J Robson, Julie MW Wallace, Maxine P Bonham, and Laura Nichol for study execution and data collection; Susan Jebb for study design; and Kirsten Rennie for sample size determination.

Competing interests: KRF receives consulting fees for serving on the scientific advisory panel of Slimming World, a company that offers a support service for weight loss. This company was not involved in this trial but as it is similar to Rosemary Conley and Weight Watchers, the conclusions may have implications for the company.

Funding: The study was sponsored by the BBC. The BBC had no role in the study design; collection, analysis, or interpretation of data; or report writing.

Ethical approval: South East multicentre research ethics committee, approval number MREC 01/01/44. Local ethics committee approval was also obtained at each centre.

References

1. Department of Health. White paper on public health. Saving lives: our healthier nation. London: Stationery Office, 1999.

2. Royal College of Physicians. Storing up problems: the medical case for a slimmer nation. London: RCP, 2004. [ PMC free article] [ PubMed]

7. Perri MG. The maintenance of treatment effects in the long term management of obesity. Clin Psychol Sci Pract 1998;5: 526-43. [ Google Scholar]

8. Atkins R. Dr Atkins' new diet revolution. South Dakota: Vermillion, 1999.

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Randomised controlled trial of four commercial weight loss programmes in the UK: initial findings from the BBC "diet trials"

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Helen Truby, senior lecturer in nutrition and dietetics, 1 Sue Baic, lecturer in nutrition, 2 Anne deLooy, professor of dietetics, 3 Kenneth R Fox, professor of exercise science, 2 M Barbara E Livingstone, professor of nutrition, 4 Catherine M Logan, PhD student, 4 Ian A Macdonald, professor, 5 Linda M Morgan, professor of nutritional endocrinology, 1 Moira A Taylor, lecturer in nutrition and dietetics, 5 and D Joe Millward, professor of human nutrition 1 Objective To compare the effectiveness of four commercial weight loss diets available to adults in the United Kingdom.

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By Lisa Rapaport

(Reuters Health) - While extremely low-carbohydrate diets may aid short term weight loss, they have mixed effects on health markers that can contribute to heart disease risk, according to new recommendations from the National Lipid Association.

Based on a review of existing research, the scientific statement emphasizes some advantages of a ketogenic, or very low-carb, diet including appetite suppression, lower lipid levels and lower blood sugar in people with diabetes.

But a keto diet is also associated with spikes in the "bad" cholesterol that can build up in blood vessels and lead to clots, known as low-density lipoprotein cholesterol (LDL-C).

Over six months, people may lose more weight with popular low-carb diets like the Atkins, ketogenic, South Beach, and Zone diets, according to the recommendations published in the Journal of Clinical Lipidology.

But after a year, weight loss with these diets is similar to what people can achieve with diets that allow more carbohydrates, according to the recommendations. Extremely low-carb diets can also be harder to stick with over time, and may severely restrict nutrient-dense foods that offer cardiovascular benefits, the recommendations stress.

There doesn't appear to be a meaningful difference between low-carb and other types of diets for other markers of cardiometabolic health like blood pressure.

"While some patients prefer a low-carbohydrate eating pattern, which may be reasonable for short periods of time, long-term compliance is challenging, and long-term benefits and risks are not fully understood, especially with ketogenic diets," said Carol Kirkpatrick, lead author of the recommendations and a researcher at Idaho State University in Pocatello.

With ketogenic diets, people typically eat very few carbs and consume a lot of fat, putting the body into a metabolic state known as ketosis. This can make the body more efficient at burning fat for energy and trigger reductions in blood sugar, previous research has found.

Some people on ketogenic diets have lost two to three times more weight than individuals with different eating habits, but much of this is based on short-term results.

"Weight loss with any dietary strategy is difficult and there are many factors that impact a person's ability to lose weight and maintain that weight loss," Kirkpatrick said by email. "Behavioral strategies, social support, and adequate physical activity have proven helpful for enhancing weight loss and helping with weight loss maintenance, no matter what type of weight loss diet is employed by a person needing to lose body fat."

People who might benefit from following an extremely low-carb diet for two to six months include individuals with diabetes and individuals with high levels of triglycerides in their blood, according to the recommendations.

Patients with a history of dangerously high cholesterol levels should avoid keto and extremely low-carb diets, the recommendations also note.

More research over longer periods of time is still needed to determine whether keto or low-carb diets might be harmful or helpful to people trying to lose weight and improve their overall health, said Andrew Mente, a researcher at McMaster University in Hamilton, Canada, who wasn't involved in the study.

"Since there are no long-term trials of low-carb diets and health outcomes, this review is only able to report on intermediate risk markers rather than actual clinical outcome events like heart attacks, strokes, cardiovascular death, new diabetes events, and total mortality," Mente said by email.

While diets aren't one size fits all, most people should aim for a wide variety of healthy foods, said Dr. Sara Seidelmann, a cardiologist and nutritionist at Brigham and Women's Hospital and Harvard Medical School in Boston.

Ideally, adopt a diet full of plants and whole foods that provides overall cardio-protective qualities: rich in whole grains, vegetables, fruits, nuts, and legumes; eliminate processed foods and trans fats; limit refined grains, saturated fats, red meat and added sugars," Seidelmann, who wasn't involved in the study, said by email. "Adults that are interested in pursuing a very low or low carbohydrate diet for weight loss should consult with their clinician in order to weigh the risks and benefits of various diets and to share in the decision making process."

SOURCE: https://bit.ly/2nK56GL Journal of Clinical Lipidology, online September 13, 2019.

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Low-carb 'keto' diets have some health benefits and some risks

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Based on a review of existing research, the scientific statement emphasizes some advantages of a ketogenic, or very low-carb, diet including appetite suppression, lower lipid levels and lower blood sugar in people with diabetes. Over six months, people may lose more weight with popular low-carb diets

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Cut your risk of diabetes | Atkins Low Carb Diet

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You can reduce your risk of getting diabetes significantly by making a few simple changes, like opting for a low carb diet. Read about it in our blog!

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Helen Truby, senior lecturer in nutrition and dietetics, ¹ Sue Baic, lecturer in nutrition, ² Anne deLooy, professor of dietetics, ³ Kenneth R Fox, professor of exercise science, ² M Barbara E Livingstone, professor of nutrition, ⁴ Catherine M Logan, PhD student, ⁴ Ian A Macdonald, professor, ⁵ Linda M Morgan, professor of nutritional endocrinology, ¹ Moira A Taylor, lecturer in nutrition and dietetics, ⁵ and D Joe Millward, professor of human nutrition ¹

Abstract

Objective To compare the effectiveness of four commercial weight loss diets available to adults in the United Kingdom.

Design Six month multicentre randomised unblinded controlled trial.

Setting Community based sample of otherwise healthy overweight and obese adults.

Interventions Dr Atkins' new diet revolution, Slim-Fast plan, Weight Watchers pure points programme, and Rosemary Conley's eat yourself slim diet and fitness plan.

Main outcome measures Weight and body fat changes over six months.

Results All diets resulted in significant loss of body fat and weight over six months. Groups did not differ significantly but loss of body fat and weight was greater in all groups compared with the control group. In an intention to treat analysis, average weight loss was 5.9 kg and average fat loss was 4.4 kg over six months. The Atkins diet resulted in significantly higher weight loss during the first four weeks, but by the end was no more or less effective than the other diets.

Conclusions Clinically useful weight loss and fat loss can be achieved in adults who are motivated to follow commercial diets for a substantial period. Given the limited resources for weight management in the NHS, healthcare practitioners should discuss with their patients programmes known to be effective.

Trial registration Clinical trials NCT00327821.

Introduction

The prevalence of obesity and its comorbidities is increasing in the United Kingdom. Over half of British adults are now overweight, and half of these people will probably become obese. The estimated cost of obesity is £0.5bn (€0.7bn; $0.9bn) each year to the NHS and £2bn each year to the wider economy.

Most adults in the United States diet at some time, and trends in the UK are similar.⁻ Long term success rates tend to be poor, with 50% of weight loss being regained within one year.

With a market estimated to be worth £11.2bn by 2007, it is not surprising that the commercial sector has shown a keen interest in weight loss programmes. Weight Watchers, the market leader, claims to have one million members (P Hunt, personal communication, 2005). Self help books that provide weight loss strategies are often best sellers- Dr Atkins' New Diet Revolution has sold more than 10 million copies. Although commercial diets provide consumers with a plethora of choice, data on their comparative efficacy are limited.

Our study compared four popular commercial weight loss programmes with a control group. The diets-representative of the main approaches to weight management in the UK today-were the Slim-Fast plan (a meal replacement approach), Weight Watchers pure points programme (an energy controlled diet with weekly group meetings), Dr Atkins' new diet revolution (a self monitored low carbohydrate eating plan), and Rosemary Conley's eat yourself slim diet and fitness plan (a low fat diet and a weekly group exercise class). We report the changes in weight and body fat over the six month study and describe dieting behaviour and weight change in the participants at 12 months.

Methods

The trial was an unblinded randomised controlled parallel dietary intervention study with a delayed treatment control group conducted at five regional centres (Surrey University, Bristol University, Nottingham University, Ulster (Coleraine) University, and Queen Margaret University College, Edinburgh).

Recruitment strategy

We identified potential participants via a BBC advertising campaign (television and other forms of media). Participants were chosen from people who lived within 30 miles of a test centre, were aged between 18 and 65, and had a self reported body mass index between 27 and 40. Volunteers who fulfilled these preliminary inclusion criteria contacted their general practitioner for confirmation that they were eligible. Exclusion criteria were coronary heart disease; type 1 or type 2 diabetes; renal, liver, or respiratory failure; gout; obesity with known cause (Cushing's disease, hypothyroidism); previous gastric or weight loss surgery; clinical depression; eating disorders; drug or alcohol misuse; any malabsorptive state (including lactose intolerance); taking lipid lowering or anti-hypertensive drugs; taking any drugs (including orlistat and sibutramine) for weight loss; being treated for cancer; and being pregnant or breastfeeding. Participants gave full informed consent. Three hundred people returned the necessary documentation to enter baseline testing by the start date of the study (July 2002).

Protocol assignment

We estimated that 60 initial participants (44 completers) were needed per treatment group (allowing for a 25% dropout rate) for an 80% chance of identifying a true difference of 4 kg of body weight loss (3 kg body fat), with a significance level of 5%. Thus, each of the five test centres aimed to recruit 60 participants (12 for each diet group; total sample size of 300). Participants took all baseline tests before randomisation and each centre started the study within six weeks of the start date. Seven participants were subsequently excluded (). At each test centre, we stratified participants by sex and allocated them to a group using random number generation. Body mass index and age did not differ between groups or between centres.

It was not possible to blind the participants to the diet regimen and we did not attempt to blind the investigators during the study or data analysis.

Providing dietary programmes to participants

For the group based programmes (Weight Watchers and Rosemary Conley), participants attended the most convenient class and we reimbursed the costs of joining and attending one class each week. Both parent companies signed a contract committing to the provision of standard care. For Slim-Fast, we reimbursed the cost of up to two meal replacements each day and provided a copy of the Slim-Fast support pack. We gave participants in the Atkins group a copy of Dr Atkins' New Diet Revolution. We asked the members of the control group to maintain their current diet and exercise pattern and offered them any of the diets for six months at the end of study (free of charge). All participants could claim reimbursement of travel costs.

Study protocol and monitoring

Measures at baseline, two months, and six months included weight, height, waist circumference, blood pressure, and fasting blood and body fat by whole body dual x ray absorptiometry. We excluded the absorptiometry data of four participants from all analyses because of errors at baseline. Monthly test centre measurements recorded weight in light clothing, blood pressure, and waist circumference. We monitored renal function in the Atkins group by urea, electrolytes, and cystatin C, and these measures remained within the reference ranges. Participants completed a seven day diet and activity diary at baseline, eight weeks, and 24 weeks. We gave no dietary or exercise advice so as not to compromise the study. When we analysed the food diaries at two months we found that some of the participants on the Atkins diet were not taking supplements of micronutrients as advised in the book. Therefore, from week 10 we offered free daily supplements of multivitamins. All participants who withdrew completed a short exit questionnaire. At 12 months, we recorded the weight and dieting behaviour from six to 12 months of all participants still willing to attend test centres.

Statistical analysis

The primary analysis was on an intention to treat basis, with baseline values carried forward to replace missing values (one participant was not used in this analysis as she withdrew because of pregnancy). A secondary analysis focused on the outcomes of these dietary approaches in the most motivated subjects who provided complete data (baseline, two months, and six months). Analysis of variance showed that the test centre did not affect total weight loss in participants who completed. Attrition rates did not differ between centres, so we analysed data from all participants together. Baseline weight correlated with total weight loss ( r = 0.33, P < 0.001) and was therefore used as a covariate in the analysis of weight loss over time, which uses repeated measures analysis of covariance. In the intention to treat analysis, we used ANOVA to examine differences between groups; where ANOVA indicated a significant group effect, we performed post hoc pairwise testing with Tukey's HSD (honestly significantly different) test. Before parametric testing, we assessed homogeneity of variance with Levene's statistic and tested for normal distribution; we used Welch's F statistic if variance of the dependent variable was not equal across groups. We analysed differences between participants who completed and withdrew with t tests for continuous variables (such as age) and χ ² for categorical variables (such as sex and diet group).

Results

shows the baseline demographics and anthropometric measures. The mean time spent on the diet was 24.3 (SD 1.56) weeks and did not differ between diet groups ( F = 2.0, P = 0.12).

Table 1

Weight and fat loss

Monthly weight loss by using all available data () was high initially but then slowed. Mean weight loss was significantly higher in the Atkins group than in the other diet groups during the first four weeks ( F = 6.9, df = 3, P < 0.001): Atkins 4.4 kg (SD 2.45, range 13.5 to 0.3 kg), Weight Watchers 2.86 kg (2.23, 12.9 to - 0.9 kg), Slim-Fast 2.68 kg (2.33, 9.4 to - 1.8 kg), and Rosemary Conley 3.17 kg (2.02, 8.1 to - 2.0 kg). At other time points, mean weight loss did not vary significantly between the diet groups ().

Table 2

Loss of body fat showed similar patterns (). In the first two months, the greatest loss of body fat was seen in the Atkins group; this loss was not significantly different from that seen in the Weight Watchers or Rosemary Conley groups, but it was significantly greater than that seen in the Slim-Fast group. Fat loss was significantly greater in all four diet groups than in the control group. Between two and six months, fat loss (kg and percentage) slowed down, and the diets groups did not differ significantly. Between baseline and six months fat loss did not differ between diet groups, but fat loss in all diet groups was significantly greater than in the control group. All diets resulted in a reduction in waist circumference. Waist reduction (at six months) was highly correlated with total weight loss ( r = 0.81, P < 0.001) and moderately correlated with percentage of body fat lost ( r = 0.64, P < 0.001).

Cardiac risk factors

We found few significant differences in cardiac risk factors between the diets groups and the control group (). Initially, the fall in systolic pressure in the Atkins group was significantly greater than in the Slim-Fast group but not the other groups, probably because of the relatively greater initial weight loss in the Atkins group. Regression analysis showed that total weight loss over time had the greatest influence on systolic and diastolic pressure (adjusted R ² 0.61 for change in systolic pressure and 0.79 for change in diastolic pressure).

Table 3

Glucose concentrations fell slightly over time; only in the Weight Watchers group was fasting glucose significantly lower than in the control group. In the first two months, a significant but small drop in total cholesterol was seen in all diet groups except for the Atkins group. By six months, cholesterol had fallen significantly compared with the control group only in the Weight Watchers group (by 0.55 mmol/l).

Analysis of completers

A secondary analysis of data from participants who completed the trial shows the range of weight lost by these highly motivated participants, who probably adhered most strongly to the randomly allocated diets. shows the range of total weight lost; some participants lost more than 25 kg over the six month study period, whereas others gained weight ().

After six months all diets resulted in a clinically useful mean reduction in percentage body weight: Rosemary Conley 9.9% (SD 5.6%), Weight Watchers 9.0% (5.6%), Atkins 8.9% (5.6%), and Slim-Fast 6.8% (5.3%); no significant differences were seen between the diets but all were more successful than no diet (controls gained 0.95%, 3.3%). The proportion of participants who completed the trial and lost at least 10% of their body weight at six months was 46% for the Rosemary Conley group, 45% for the Atkins group, 36% for the Weight Watchers group, and 21% for the Slim-Fast group. These losses were achieved despite the random allocation of diets.

Compliance with the diets

Reported attendance at slimming clubs was similar at two months (Rosemary Conley 79%, Weight Watchers 66%) and six months (47%, 47%). Slim-Fast recommends 14 meal replacements each week; participants reported 10 each week at two months and eight at six months. With the Atkins diet, reported portions of carbohydrate foods fell from 40 each day at baseline to five at two months and seven at six months.

Withdrawal

Eighty three (28%) participants had withdrawn by six months (); 53 (64% of the total number) had withdrawn by week 8, and at this time only seven (8%) participants who withdrew had lost more than 5% of their body weight compared with 53 (25%) who completed the trial. Older participants were significantly more likely to complete than younger ones (mean age 41.6 (9.9) v 36.8 (10.4); t = - 3.7, P < 0.001; 95% confidence interval 2.3 to 7.4). No differences in diet, centre, or sex were found between participants who completed or withdrew. Withdrawal in the control group (21; 35%) was mostly because participants did not wish to delay dieting.

Table 4

Follow-up at 12 months

At 12 months, 158 participants (54% of the original sample) returned data; 29 had originally been allocated to the Atkins diet, 33 to Weight Watchers, 33 to Slim-Fast, 35 to Rosemary Conley, and 28 to the control group. Dieting behaviour had changed considerably: only 58 (45%) were still keeping to their originally allocated diets (nine to Atkins, 20 to Weight Watchers, nine to Slim-Fast, 20 to Rosemary Conley). Twenty five (19%) had swapped dietary programmes and 47 (36%) were following their own diet or exercise plan. More participants in the unsupported programmes (Atkins diet and Slim-Fast) withdrew than in the supported programmes (χ ² = 8.34, df = 3.0, P = 0.04). Participants in the control group who had switched to dieting (mean weight loss 6.37, SD 4.5 kg) also preferred group based approaches because just over half chose Weight Watchers.

Because so many participants changed diets (25% of men and 29% of women), we also analysed weight loss in participants who had maintained the diet to which they were initially allocated (). Statistical analysis is limited by sample size but indicates that weight rebound after the initial six months was higher in the unsupported programmes; however, all diets resulted in a clinically useful weight loss of around 10% after 12 months in participants who had persisted with the diet allocated.

Table 5

Discussion

Clinically beneficial weight loss is possible through commercially available strategies, and reduced blood pressure and waist circumference accompany weight loss. The four different approaches were equally effective after six months. Reductions in weight and body fat were seen with the Atkins diet within the first eight weeks of dieting, so that the large weight changes seen with low carbohydrate diets are not caused by loss of body water alone. The Atkins diet had no detrimental effects on total cholesterol concentrations or renal function, although the overall safety of the diet was not tested.

The range of absolute weight loss in participants who completed the study was wide. Importantly, we did not try to standardise energy intake across the groups, so that the effects reflect the participants' interpretation of and compliance with the diet allocated. However, the mean absolute weight loss of around 8 kg is comparable to other studies. Compliance with each diet varied greatly. Weight can be lost only by a sustained negative balance of energy, so the degree of adherence to a diet will predict success or failure if activity levels remain constant. More information is needed to enable health professionals to decide which dietary approach may suit their patients. Currently, we cannot predict the dietary approach best suited to each person to lose weight and maintain weight loss in the longer term, but it is clear that "one size does not fit all."

Our study was used to make the BBC series on diet trials, which featured a small number of people. Since motivation to meet goal weights and patients' expectations of weight loss are key determinants of success, participants may have been influenced by the media interest. Overall, around 5% of participants were featured in the television programmes, and most participants knew that they would not be filmed within the first few weeks. Excluding data from the 15 filmed participants had no effect on the overall statistical outcomes shown in this study. The withdrawal rate was comparable to other longitudinal studies of weight loss.⁻

No dietary differences were apparent at six months, but behaviour from six to 12 months points towards an advantage of programmes based on group support. The need for a "quick fix" and the relative lack of interest that people show in achieving modest weight loss contribute to lack of adherence to most diets in the long term. People who had kept to their allocated diet lost about 10% of their weight, despite some weight rebound, but some regression to the mean effect was seen. These results provide information on the "best effect" that the most highly motivated subjects may hope to achieve over one year.

In conclusion, commercial weight loss programmes can help people with uncomplicated obesity. Our study provides data on how much weight patients can expect to lose by dieting, and these data could help practitioners in managing patients' some-times unrealistic expectations of weight loss targets. The benefits to health of modest weight loss and maintaining that loss over long periods need to be emphasised.
What is already known about this topic
The prevalence of obesity and overweight with its subsequent comorbidities is growing in the UK

Commercial diets are an increasingly popular option for weight management
What this study adds
The comparative efficacy of four commercial diets was similar

The health benefits associated with a modest loss of weight (5-10% body weight) can be gained by people following a range of dietary regimens for six months with little support from health professionals

Notes

Contributors: HT was the principal investigator and is guarantor. She contributed to the study design, data analysis, interpretation, drafting, and writing of the paper. DJM and LMM contributed to the study design, data analysis, interpretation, drafting, and writing of the paper. KRF contributed to the study design, interpretation, reporting, and critical review of paper. SB contributed to study execution, data collection, and critical review of the paper. IAM, MAT, MBEL, CML, and AdeL contributed to the study planning, interpretation, reporting, and critical review of the paper. Thanks to David Lovell for statistical advice; Manana Stanley, Rebecca Hiscutt, and Anne Herriot for planning, study execution, and data collection; Monique Raats and Richard Shepherd for study planning; Kathryn Hart, Rachel Barratt, Karen Sargent, Sarah Jones, Julie Littlewood, Sujata Dissanayake, Elizabeth Simpson, and Michelle Hazell for data collection; Mark Davis for study design and data collection; Katherine Collings for planning, study execution, and data collection; Paula J Robson, Julie MW Wallace, Maxine P Bonham, and Laura Nichol for study execution and data collection; Susan Jebb for study design; and Kirsten Rennie for sample size determination.

Competing interests: KRF receives consulting fees for serving on the scientific advisory panel of Slimming World, a company that offers a support service for weight loss. This company was not involved in this trial but as it is similar to Rosemary Conley and Weight Watchers, the conclusions may have implications for the company.

Funding: The study was sponsored by the BBC. The BBC had no role in the study design; collection, analysis, or interpretation of data; or report writing.

Ethical approval: South East multicentre research ethics committee, approval number MREC 01/01/44. Local ethics committee approval was also obtained at each centre.

References

1. Department of Health. White paper on public health. Saving lives: our healthier nation. London: Stationery Office, 1999.

2. Royal College of Physicians. Storing up problems: the medical case for a slimmer nation. London: RCP, 2004. [ PMC free article] [ PubMed]

7. Perri MG. The maintenance of treatment effects in the long term management of obesity. Clin Psychol Sci Pract 1998;5: 526-43. [ Google Scholar]

8. Atkins R. Dr Atkins' new diet revolution. South Dakota: Vermillion, 1999.

# data[].attributes.attachment_link.title
Randomised controlled trial of four commercial weight loss programmes in the UK: initial findings from the BBC "diet trials"

# data[].attributes.attachment_link.description
Helen Truby, senior lecturer in nutrition and dietetics, 1 Sue Baic, lecturer in nutrition, 2 Anne deLooy, professor of dietetics, 3 Kenneth R Fox, professor of exercise science, 2 M Barbara E Livingstone, professor of nutrition, 4 Catherine M Logan, PhD student, 4 Ian A Macdonald, professor, 5 Linda M Morgan, professor of nutritional endocrinology, 1 Moira A Taylor, lecturer in nutrition and dietetics, 5 and D Joe Millward, professor of human nutrition 1 Objective To compare the effectiveness of four commercial weight loss diets available to adults in the United Kingdom.

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Helen Truby, senior lecturer in nutrition and dietetics, ¹ Sue Baic, lecturer in nutrition, ² Anne deLooy, professor of dietetics, ³ Kenneth R Fox, professor of exercise science, ² M Barbara E Livingstone, professor of nutrition, ⁴ Catherine M Logan, PhD student, ⁴ Ian A Macdonald, professor, ⁵ Linda M Morgan, professor of nutritional endocrinology, ¹ Moira A Taylor, lecturer in nutrition and dietetics, ⁵ and D Joe Millward, professor of human nutrition ¹

Abstract

Objective To compare the effectiveness of four commercial weight loss diets available to adults in the United Kingdom.

Design Six month multicentre randomised unblinded controlled trial.

Setting Community based sample of otherwise healthy overweight and obese adults.

Interventions Dr Atkins' new diet revolution, Slim-Fast plan, Weight Watchers pure points programme, and Rosemary Conley's eat yourself slim diet and fitness plan.

Main outcome measures Weight and body fat changes over six months.

Results All diets resulted in significant loss of body fat and weight over six months. Groups did not differ significantly but loss of body fat and weight was greater in all groups compared with the control group. In an intention to treat analysis, average weight loss was 5.9 kg and average fat loss was 4.4 kg over six months. The Atkins diet resulted in significantly higher weight loss during the first four weeks, but by the end was no more or less effective than the other diets.

Conclusions Clinically useful weight loss and fat loss can be achieved in adults who are motivated to follow commercial diets for a substantial period. Given the limited resources for weight management in the NHS, healthcare practitioners should discuss with their patients programmes known to be effective.

Trial registration Clinical trials NCT00327821.

Introduction

The prevalence of obesity and its comorbidities is increasing in the United Kingdom. Over half of British adults are now overweight, and half of these people will probably become obese. The estimated cost of obesity is £0.5bn (€0.7bn; $0.9bn) each year to the NHS and £2bn each year to the wider economy.

Most adults in the United States diet at some time, and trends in the UK are similar.⁻ Long term success rates tend to be poor, with 50% of weight loss being regained within one year.

With a market estimated to be worth £11.2bn by 2007, it is not surprising that the commercial sector has shown a keen interest in weight loss programmes. Weight Watchers, the market leader, claims to have one million members (P Hunt, personal communication, 2005). Self help books that provide weight loss strategies are often best sellers- Dr Atkins' New Diet Revolution has sold more than 10 million copies. Although commercial diets provide consumers with a plethora of choice, data on their comparative efficacy are limited.

Our study compared four popular commercial weight loss programmes with a control group. The diets-representative of the main approaches to weight management in the UK today-were the Slim-Fast plan (a meal replacement approach), Weight Watchers pure points programme (an energy controlled diet with weekly group meetings), Dr Atkins' new diet revolution (a self monitored low carbohydrate eating plan), and Rosemary Conley's eat yourself slim diet and fitness plan (a low fat diet and a weekly group exercise class). We report the changes in weight and body fat over the six month study and describe dieting behaviour and weight change in the participants at 12 months.

Methods

The trial was an unblinded randomised controlled parallel dietary intervention study with a delayed treatment control group conducted at five regional centres (Surrey University, Bristol University, Nottingham University, Ulster (Coleraine) University, and Queen Margaret University College, Edinburgh).

Recruitment strategy

We identified potential participants via a BBC advertising campaign (television and other forms of media). Participants were chosen from people who lived within 30 miles of a test centre, were aged between 18 and 65, and had a self reported body mass index between 27 and 40. Volunteers who fulfilled these preliminary inclusion criteria contacted their general practitioner for confirmation that they were eligible. Exclusion criteria were coronary heart disease; type 1 or type 2 diabetes; renal, liver, or respiratory failure; gout; obesity with known cause (Cushing's disease, hypothyroidism); previous gastric or weight loss surgery; clinical depression; eating disorders; drug or alcohol misuse; any malabsorptive state (including lactose intolerance); taking lipid lowering or anti-hypertensive drugs; taking any drugs (including orlistat and sibutramine) for weight loss; being treated for cancer; and being pregnant or breastfeeding. Participants gave full informed consent. Three hundred people returned the necessary documentation to enter baseline testing by the start date of the study (July 2002).

Protocol assignment

We estimated that 60 initial participants (44 completers) were needed per treatment group (allowing for a 25% dropout rate) for an 80% chance of identifying a true difference of 4 kg of body weight loss (3 kg body fat), with a significance level of 5%. Thus, each of the five test centres aimed to recruit 60 participants (12 for each diet group; total sample size of 300). Participants took all baseline tests before randomisation and each centre started the study within six weeks of the start date. Seven participants were subsequently excluded (). At each test centre, we stratified participants by sex and allocated them to a group using random number generation. Body mass index and age did not differ between groups or between centres.

It was not possible to blind the participants to the diet regimen and we did not attempt to blind the investigators during the study or data analysis.

Providing dietary programmes to participants

For the group based programmes (Weight Watchers and Rosemary Conley), participants attended the most convenient class and we reimbursed the costs of joining and attending one class each week. Both parent companies signed a contract committing to the provision of standard care. For Slim-Fast, we reimbursed the cost of up to two meal replacements each day and provided a copy of the Slim-Fast support pack. We gave participants in the Atkins group a copy of Dr Atkins' New Diet Revolution. We asked the members of the control group to maintain their current diet and exercise pattern and offered them any of the diets for six months at the end of study (free of charge). All participants could claim reimbursement of travel costs.

Study protocol and monitoring

Measures at baseline, two months, and six months included weight, height, waist circumference, blood pressure, and fasting blood and body fat by whole body dual x ray absorptiometry. We excluded the absorptiometry data of four participants from all analyses because of errors at baseline. Monthly test centre measurements recorded weight in light clothing, blood pressure, and waist circumference. We monitored renal function in the Atkins group by urea, electrolytes, and cystatin C, and these measures remained within the reference ranges. Participants completed a seven day diet and activity diary at baseline, eight weeks, and 24 weeks. We gave no dietary or exercise advice so as not to compromise the study. When we analysed the food diaries at two months we found that some of the participants on the Atkins diet were not taking supplements of micronutrients as advised in the book. Therefore, from week 10 we offered free daily supplements of multivitamins. All participants who withdrew completed a short exit questionnaire. At 12 months, we recorded the weight and dieting behaviour from six to 12 months of all participants still willing to attend test centres.

Statistical analysis

The primary analysis was on an intention to treat basis, with baseline values carried forward to replace missing values (one participant was not used in this analysis as she withdrew because of pregnancy). A secondary analysis focused on the outcomes of these dietary approaches in the most motivated subjects who provided complete data (baseline, two months, and six months). Analysis of variance showed that the test centre did not affect total weight loss in participants who completed. Attrition rates did not differ between centres, so we analysed data from all participants together. Baseline weight correlated with total weight loss ( r = 0.33, P < 0.001) and was therefore used as a covariate in the analysis of weight loss over time, which uses repeated measures analysis of covariance. In the intention to treat analysis, we used ANOVA to examine differences between groups; where ANOVA indicated a significant group effect, we performed post hoc pairwise testing with Tukey's HSD (honestly significantly different) test. Before parametric testing, we assessed homogeneity of variance with Levene's statistic and tested for normal distribution; we used Welch's F statistic if variance of the dependent variable was not equal across groups. We analysed differences between participants who completed and withdrew with t tests for continuous variables (such as age) and χ ² for categorical variables (such as sex and diet group).

Results

shows the baseline demographics and anthropometric measures. The mean time spent on the diet was 24.3 (SD 1.56) weeks and did not differ between diet groups ( F = 2.0, P = 0.12).

Table 1

Weight and fat loss

Monthly weight loss by using all available data () was high initially but then slowed. Mean weight loss was significantly higher in the Atkins group than in the other diet groups during the first four weeks ( F = 6.9, df = 3, P < 0.001): Atkins 4.4 kg (SD 2.45, range 13.5 to 0.3 kg), Weight Watchers 2.86 kg (2.23, 12.9 to - 0.9 kg), Slim-Fast 2.68 kg (2.33, 9.4 to - 1.8 kg), and Rosemary Conley 3.17 kg (2.02, 8.1 to - 2.0 kg). At other time points, mean weight loss did not vary significantly between the diet groups ().

Table 2

Loss of body fat showed similar patterns (). In the first two months, the greatest loss of body fat was seen in the Atkins group; this loss was not significantly different from that seen in the Weight Watchers or Rosemary Conley groups, but it was significantly greater than that seen in the Slim-Fast group. Fat loss was significantly greater in all four diet groups than in the control group. Between two and six months, fat loss (kg and percentage) slowed down, and the diets groups did not differ significantly. Between baseline and six months fat loss did not differ between diet groups, but fat loss in all diet groups was significantly greater than in the control group. All diets resulted in a reduction in waist circumference. Waist reduction (at six months) was highly correlated with total weight loss ( r = 0.81, P < 0.001) and moderately correlated with percentage of body fat lost ( r = 0.64, P < 0.001).

Cardiac risk factors

We found few significant differences in cardiac risk factors between the diets groups and the control group (). Initially, the fall in systolic pressure in the Atkins group was significantly greater than in the Slim-Fast group but not the other groups, probably because of the relatively greater initial weight loss in the Atkins group. Regression analysis showed that total weight loss over time had the greatest influence on systolic and diastolic pressure (adjusted R ² 0.61 for change in systolic pressure and 0.79 for change in diastolic pressure).

Table 3

Glucose concentrations fell slightly over time; only in the Weight Watchers group was fasting glucose significantly lower than in the control group. In the first two months, a significant but small drop in total cholesterol was seen in all diet groups except for the Atkins group. By six months, cholesterol had fallen significantly compared with the control group only in the Weight Watchers group (by 0.55 mmol/l).

Analysis of completers

A secondary analysis of data from participants who completed the trial shows the range of weight lost by these highly motivated participants, who probably adhered most strongly to the randomly allocated diets. shows the range of total weight lost; some participants lost more than 25 kg over the six month study period, whereas others gained weight ().

After six months all diets resulted in a clinically useful mean reduction in percentage body weight: Rosemary Conley 9.9% (SD 5.6%), Weight Watchers 9.0% (5.6%), Atkins 8.9% (5.6%), and Slim-Fast 6.8% (5.3%); no significant differences were seen between the diets but all were more successful than no diet (controls gained 0.95%, 3.3%). The proportion of participants who completed the trial and lost at least 10% of their body weight at six months was 46% for the Rosemary Conley group, 45% for the Atkins group, 36% for the Weight Watchers group, and 21% for the Slim-Fast group. These losses were achieved despite the random allocation of diets.

Compliance with the diets

Reported attendance at slimming clubs was similar at two months (Rosemary Conley 79%, Weight Watchers 66%) and six months (47%, 47%). Slim-Fast recommends 14 meal replacements each week; participants reported 10 each week at two months and eight at six months. With the Atkins diet, reported portions of carbohydrate foods fell from 40 each day at baseline to five at two months and seven at six months.

Withdrawal

Eighty three (28%) participants had withdrawn by six months (); 53 (64% of the total number) had withdrawn by week 8, and at this time only seven (8%) participants who withdrew had lost more than 5% of their body weight compared with 53 (25%) who completed the trial. Older participants were significantly more likely to complete than younger ones (mean age 41.6 (9.9) v 36.8 (10.4); t = - 3.7, P < 0.001; 95% confidence interval 2.3 to 7.4). No differences in diet, centre, or sex were found between participants who completed or withdrew. Withdrawal in the control group (21; 35%) was mostly because participants did not wish to delay dieting.

Table 4

Follow-up at 12 months

At 12 months, 158 participants (54% of the original sample) returned data; 29 had originally been allocated to the Atkins diet, 33 to Weight Watchers, 33 to Slim-Fast, 35 to Rosemary Conley, and 28 to the control group. Dieting behaviour had changed considerably: only 58 (45%) were still keeping to their originally allocated diets (nine to Atkins, 20 to Weight Watchers, nine to Slim-Fast, 20 to Rosemary Conley). Twenty five (19%) had swapped dietary programmes and 47 (36%) were following their own diet or exercise plan. More participants in the unsupported programmes (Atkins diet and Slim-Fast) withdrew than in the supported programmes (χ ² = 8.34, df = 3.0, P = 0.04). Participants in the control group who had switched to dieting (mean weight loss 6.37, SD 4.5 kg) also preferred group based approaches because just over half chose Weight Watchers.

Because so many participants changed diets (25% of men and 29% of women), we also analysed weight loss in participants who had maintained the diet to which they were initially allocated (). Statistical analysis is limited by sample size but indicates that weight rebound after the initial six months was higher in the unsupported programmes; however, all diets resulted in a clinically useful weight loss of around 10% after 12 months in participants who had persisted with the diet allocated.

Table 5

Discussion

Clinically beneficial weight loss is possible through commercially available strategies, and reduced blood pressure and waist circumference accompany weight loss. The four different approaches were equally effective after six months. Reductions in weight and body fat were seen with the Atkins diet within the first eight weeks of dieting, so that the large weight changes seen with low carbohydrate diets are not caused by loss of body water alone. The Atkins diet had no detrimental effects on total cholesterol concentrations or renal function, although the overall safety of the diet was not tested.

The range of absolute weight loss in participants who completed the study was wide. Importantly, we did not try to standardise energy intake across the groups, so that the effects reflect the participants' interpretation of and compliance with the diet allocated. However, the mean absolute weight loss of around 8 kg is comparable to other studies. Compliance with each diet varied greatly. Weight can be lost only by a sustained negative balance of energy, so the degree of adherence to a diet will predict success or failure if activity levels remain constant. More information is needed to enable health professionals to decide which dietary approach may suit their patients. Currently, we cannot predict the dietary approach best suited to each person to lose weight and maintain weight loss in the longer term, but it is clear that "one size does not fit all."

Our study was used to make the BBC series on diet trials, which featured a small number of people. Since motivation to meet goal weights and patients' expectations of weight loss are key determinants of success, participants may have been influenced by the media interest. Overall, around 5% of participants were featured in the television programmes, and most participants knew that they would not be filmed within the first few weeks. Excluding data from the 15 filmed participants had no effect on the overall statistical outcomes shown in this study. The withdrawal rate was comparable to other longitudinal studies of weight loss.⁻

No dietary differences were apparent at six months, but behaviour from six to 12 months points towards an advantage of programmes based on group support. The need for a "quick fix" and the relative lack of interest that people show in achieving modest weight loss contribute to lack of adherence to most diets in the long term. People who had kept to their allocated diet lost about 10% of their weight, despite some weight rebound, but some regression to the mean effect was seen. These results provide information on the "best effect" that the most highly motivated subjects may hope to achieve over one year.

In conclusion, commercial weight loss programmes can help people with uncomplicated obesity. Our study provides data on how much weight patients can expect to lose by dieting, and these data could help practitioners in managing patients' some-times unrealistic expectations of weight loss targets. The benefits to health of modest weight loss and maintaining that loss over long periods need to be emphasised.
What is already known about this topic
The prevalence of obesity and overweight with its subsequent comorbidities is growing in the UK

Commercial diets are an increasingly popular option for weight management
What this study adds
The comparative efficacy of four commercial diets was similar

The health benefits associated with a modest loss of weight (5-10% body weight) can be gained by people following a range of dietary regimens for six months with little support from health professionals

Notes

Contributors: HT was the principal investigator and is guarantor. She contributed to the study design, data analysis, interpretation, drafting, and writing of the paper. DJM and LMM contributed to the study design, data analysis, interpretation, drafting, and writing of the paper. KRF contributed to the study design, interpretation, reporting, and critical review of paper. SB contributed to study execution, data collection, and critical review of the paper. IAM, MAT, MBEL, CML, and AdeL contributed to the study planning, interpretation, reporting, and critical review of the paper. Thanks to David Lovell for statistical advice; Manana Stanley, Rebecca Hiscutt, and Anne Herriot for planning, study execution, and data collection; Monique Raats and Richard Shepherd for study planning; Kathryn Hart, Rachel Barratt, Karen Sargent, Sarah Jones, Julie Littlewood, Sujata Dissanayake, Elizabeth Simpson, and Michelle Hazell for data collection; Mark Davis for study design and data collection; Katherine Collings for planning, study execution, and data collection; Paula J Robson, Julie MW Wallace, Maxine P Bonham, and Laura Nichol for study execution and data collection; Susan Jebb for study design; and Kirsten Rennie for sample size determination.

Competing interests: KRF receives consulting fees for serving on the scientific advisory panel of Slimming World, a company that offers a support service for weight loss. This company was not involved in this trial but as it is similar to Rosemary Conley and Weight Watchers, the conclusions may have implications for the company.

Funding: The study was sponsored by the BBC. The BBC had no role in the study design; collection, analysis, or interpretation of data; or report writing.

Ethical approval: South East multicentre research ethics committee, approval number MREC 01/01/44. Local ethics committee approval was also obtained at each centre.

References

1. Department of Health. White paper on public health. Saving lives: our healthier nation. London: Stationery Office, 1999.

2. Royal College of Physicians. Storing up problems: the medical case for a slimmer nation. London: RCP, 2004. [ PMC free article] [ PubMed]

7. Perri MG. The maintenance of treatment effects in the long term management of obesity. Clin Psychol Sci Pract 1998;5: 526-43. [ Google Scholar]

8. Atkins R. Dr Atkins' new diet revolution. South Dakota: Vermillion, 1999.

# data[].attributes.attachment_link.title
Randomised controlled trial of four commercial weight loss programmes in the UK: initial findings from the BBC "diet trials"

# data[].attributes.attachment_link.description
Helen Truby, senior lecturer in nutrition and dietetics, 1 Sue Baic, lecturer in nutrition, 2 Anne deLooy, professor of dietetics, 3 Kenneth R Fox, professor of exercise science, 2 M Barbara E Livingstone, professor of nutrition, 4 Catherine M Logan, PhD student, 4 Ian A Macdonald, professor, 5 Linda M Morgan, professor of nutritional endocrinology, 1 Moira A Taylor, lecturer in nutrition and dietetics, 5 and D Joe Millward, professor of human nutrition 1 Objective To compare the effectiveness of four commercial weight loss diets available to adults in the United Kingdom.

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Atkins Diet Alert

Dear Reader:

Welcome to AtkinsDietAlert.org, a resource for physicians and laypeople with questions and concerns about high-protein diets.

This Web site offers the latest news and information about these diets, as well as a registry where dieters can record any health complications they've experienced.

AtkinsDietAlert.org is brought to you by the Physicians Committee for Responsible Medicine, a leading advocate for preventive medicine, especially good nutrition. PCRM has been speaking out about the dangers of high-protein diets since its founding in 1985. Studies show that meat-heavy, high-protein eating patterns are, over the long run, linked to osteoporosis, heart disease, colon cancer, and renal disease, and pose particular dangers for people with diabetes.

Given the seriousness of these health risks, and the strength of the scientific evidence currently available, PCRM hopes this Web site will encourage people to be wary of high-protein diets and to choose healthier options. PCRM is also concerned about possible legal liability for doctors who prescribe these diets.

If you are a health care practitioner, please read our physician advisory and consider recommending against high-protein diets. If you are a layperson on one of the high-protein diets, please read our consumer advisory and consider joining our registry. It will only take a few minutes of your time, but it could provide important information on diet-related health risks.

Thanks for visiting. We wish you the very best of health.

Sincerely,

Neal D. Barnard, M.D.
President
Physicians Committee for Responsible Medicine

# data[].attributes.attachment_link.description
Dear Reader: Welcome to AtkinsDietAlert.org, a resource for physicians and laypeople with questions and concerns about high-protein diets. This Web site offers the latest news and information about these diets, as well as a registry where dieters can record any health complications they've experienced.

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Cut your risk of diabetes | Atkins Low Carb Diet

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You can reduce your risk of getting diabetes significantly by making a few simple changes, like opting for a low carb diet. Read about it in our blog!

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We include products we think are useful for our readers. If you buy through links on this page, we may earn a small commission. Here's our process.

The Atkins diet is a low-carb diet, usually recommended for weight loss.

Proponents of this diet claim that you can lose weight while eating as much protein and fat as you want, as long as you avoid foods high in carbs.

In the past 12 or so years, over 20 studies have shown that low-carb diets without the need for calorie counting are effective for weight loss and can lead to various health improvements.

The Atkins diet was originally promoted by the physician Dr. Robert C. Atkins, who wrote a best-selling book about it in 1972.

Since then, the Atkins diet has been popular all over the world with many more books having been written.

The diet was originally considered unhealthy and demonized by the mainstream health authorities, mostly due to its high saturated fat content. However, new studies suggest that saturated fat is harmless (, ).

Since then, the diet has been studied thoroughly and shown to lead to more weight loss and greater improvements in blood sugar, "good" HDL cholesterol, triglycerides and other health markers than low-fat diets (, ).

Despite being high in fat, it does not raise "bad" LDL cholesterol on average, though this does happen in a subset of individuals ().

The main reason why low-carb diets are so effective for weight loss is that a reduction in carbs and increased protein intake lead to reduced appetite, making you eat fewer calories without having to think about it (, ).

You can read more about the health benefits of low-carb diets in this article.

The Atkins diet is split into 4 different phases:

Phase 1 (induction): Under 20 grams of carbs per day for 2 weeks. Eat high-fat, high-protein, with low-carb vegetables like leafy greens. This kick-starts the weight loss.

Phase 2 (balancing): Slowly add more nuts, low-carb vegetables and small amounts of fruit back to your diet.

Phase 3 (fine-tuning): When you're very close to your goal weight, add more carbs to your diet until weight loss slows down.

Phase 4 (maintenance): Here you can eat as many healthy carbs as your body can tolerate without regaining weight.

However, these phases are a bit complicated and may not be necessary. You should be able to lose weight and keep it off as long as you stick to the meal plan below.

Some people choose to skip the induction phase altogether and include plenty of vegetables and fruit from the start. This approach can be very effective as well.

Others prefer to just stay in the induction phase indefinitely. This is also known as a very low-carb ketogenic diet (keto).

You should avoid these foods on the Atkins diet:

Sugar: Soft drinks, fruit juices, cakes, candy, ice cream, etc.

Grains: Wheat, spelt, rye, barley, rice.

Trans fats: Usually found in processed foods with the word "hydrogenated" on the ingredients list.

"Diet" and "low-fat" foods: These are usually very high in sugar.

High-carb vegetables: Carrots, turnips, etc (induction only).

High-carb fruits: Bananas, apples, oranges, pears, grapes (induction only).

Starches: Potatoes, sweet potatoes (induction only).

Legumes: Lentils, beans, chickpeas, etc. (induction only).

You should base your diet around these healthy foods.

Meats: Beef, pork, lamb, chicken, bacon and others.

Fatty fish and seafood: Salmon, trout, sardines, etc.

Eggs: The healthiest eggs are omega-3 enriched or pastured.

Low-carb vegetables: Kale, spinach, broccoli, asparagus and others.

Full-fat dairy: Butter, cheese, cream, full-fat yogurt.

Nuts and seeds: Almonds, macadamia nuts, walnuts, sunflower seeds, etc.

Healthy fats: Extra virgin olive oil, coconut oil, avocados and avocado oil.

As long as you base your meals around a fatty protein source with vegetables or nuts and some healthy fats, you will lose weight. It's that simple.

Beverages

Here are some drinks that are acceptable on the Atkins diet.

Water: As always, water should be your go-to beverage.

Coffee: Many studies show that coffee is high in antioxidants and quite healthy.

Green tea: A very healthy beverage.

Alcohol is also fine in small amounts. Stick to dry wines with no added sugars and avoid high-carb drinks like beer.

There are many delicious foods you can eat on the Atkins diet.

This includes foods like bacon, heavy cream, cheese and dark chocolate.

Many of these are generally considered fattening because of the high fat and calorie content.

However, when you're on a low-carb diet, your body increases its use of fat as an energy source and suppresses your appetite, reducing the risk of overeating and weight gain.

If you'd like to know more, check out this article on 6 Indulgent Foods That Are Low-Carb Friendly.

Despite what you may have heard, the Atkins diet is quite flexible.

It's only during the two-week induction phase that you need to minimize your intake of carb sources.

After induction is over, you can slowly add back healthier carbs such as higher-carb vegetables, fruits, berries, potatoes, legumes and healthier grains like oats and rice.

However, chances are that you will need to stay moderately low-carb for life, even if you reach your weight loss goals.

If you start eating the same old foods again in the same amounts as before, you will gain back the weight. This is true of any weight loss diet.

It is possible to do the Atkins diet as a vegetarian (and even vegan), but difficult.

You can use soy-based foods for protein and eat plenty of nuts and seeds. Olive oil and coconut oil are excellent plant-based fat sources.

Lacto-ovo-vegetarians can also eat eggs, cheese, butter, heavy cream and other high-fat dairy foods.

This is a sample menu for one week on the Atkins diet.

It's suitable for the induction phase, but you should add more higher-carb vegetables and some fruits as you move on to the other phases.

Monday

Tuesday

Breakfast: Bacon and eggs.

Lunch: Leftover chicken and veggies from the night before.

Dinner: Bunless cheeseburger, with vegetables and butter.

Wednesday

Thursday

Friday

Saturday

Sunday

Make sure to include a variety of different vegetables in your diet.

For a few examples of healthy and satisfying low-carb meals, check out this article on 7 Healthy Low-Carb Meals in Under 10 Minutes.

Healthy Low-Carb Snacks

Most people feel that their appetite goes down on the Atkins diet.

They tend to feel more than satisfied with 3 meals per day (sometimes only 2).

However, if you feel hungry between meals, here are a few quick healthy snacks:

Leftovers.

A hard-boiled egg or two.

A piece of cheese.

A piece of meat.

A handful of nuts.

Some Greek yogurt.

Berries and whipped cream.

Baby carrots (careful during induction).

Fruits (after induction).

It's actually very easy to follow the Atkins diet at most restaurants.

1. Get extra vegetables instead of bread, potatoes or rice.

2. Order a meal based on fatty meat or fatty fish.

3. Get some extra sauce, butter or olive oil with your meal.

It's a good rule to shop at the perimeter of the store. This is usually where the whole foods are found.

Eating organic is not necessary, but always go for the least processed option that fits your budget.

Meats: Beef, chicken, lamb, pork, bacon.

Fatty fish: Salmon, trout, etc.

Shrimp and shellfish.

Dairy: Greek yogurt, heavy cream, butter, cheese.

Vegetables: Spinach, kale, lettuce, tomatoes, broccoli, cauliflower, asparagus, onions, etc.

Berries: Blueberries, strawberries, etc.

Nuts: Almonds, macadamia nuts, walnuts, hazelnuts, etc.

Seeds: Sunflower seeds, pumpkin seeds, etc.

Fruits: Apples, pears, oranges.

Coconut oil.

Olives.

Extra virgin olive oil.

Dark chocolate.

Avocados.

Condiments: Sea salt, pepper, turmeric, cinnamon, garlic, parsley, etc.

It's highly recommended to clear your pantry of all unhealthy foods and ingredients. This includes ice cream, sodas, breakfast cereals, breads, juices and baking ingredients like sugar and wheat flour.

If you're serious about the Atkins diet, consider buying or borrowing one of the Atkins books and simply get started as soon as possible.

That being said, the detailed guide in this article should contain everything you need to succeed. To create a printable version, click here.

For recipe ideas, check out this article on 101 Healthy Low-Carb Recipes That Taste Incredible

At the end of the day, the Atkins diet is a healthy and effective way to lose weight. You won't be disappointed.

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The Atkins Diet: Everything You Need to Know

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We include products we think are useful for our readers. If you buy through links on this page, we may earn a small commission. Here's our process. The Atkins diet is a low-carb diet, usually recommended for weight loss.

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By Lisa Rapaport

(Reuters Health) - While extremely low-carbohydrate diets may aid short term weight loss, they have mixed effects on health markers that can contribute to heart disease risk, according to new recommendations from the National Lipid Association.

Based on a review of existing research, the scientific statement emphasizes some advantages of a ketogenic, or very low-carb, diet including appetite suppression, lower lipid levels and lower blood sugar in people with diabetes.

But a keto diet is also associated with spikes in the "bad" cholesterol that can build up in blood vessels and lead to clots, known as low-density lipoprotein cholesterol (LDL-C).

Over six months, people may lose more weight with popular low-carb diets like the Atkins, ketogenic, South Beach, and Zone diets, according to the recommendations published in the Journal of Clinical Lipidology.

But after a year, weight loss with these diets is similar to what people can achieve with diets that allow more carbohydrates, according to the recommendations. Extremely low-carb diets can also be harder to stick with over time, and may severely restrict nutrient-dense foods that offer cardiovascular benefits, the recommendations stress.

There doesn't appear to be a meaningful difference between low-carb and other types of diets for other markers of cardiometabolic health like blood pressure.

"While some patients prefer a low-carbohydrate eating pattern, which may be reasonable for short periods of time, long-term compliance is challenging, and long-term benefits and risks are not fully understood, especially with ketogenic diets," said Carol Kirkpatrick, lead author of the recommendations and a researcher at Idaho State University in Pocatello.

With ketogenic diets, people typically eat very few carbs and consume a lot of fat, putting the body into a metabolic state known as ketosis. This can make the body more efficient at burning fat for energy and trigger reductions in blood sugar, previous research has found.

Some people on ketogenic diets have lost two to three times more weight than individuals with different eating habits, but much of this is based on short-term results.

"Weight loss with any dietary strategy is difficult and there are many factors that impact a person's ability to lose weight and maintain that weight loss," Kirkpatrick said by email. "Behavioral strategies, social support, and adequate physical activity have proven helpful for enhancing weight loss and helping with weight loss maintenance, no matter what type of weight loss diet is employed by a person needing to lose body fat."

People who might benefit from following an extremely low-carb diet for two to six months include individuals with diabetes and individuals with high levels of triglycerides in their blood, according to the recommendations.

Patients with a history of dangerously high cholesterol levels should avoid keto and extremely low-carb diets, the recommendations also note.

More research over longer periods of time is still needed to determine whether keto or low-carb diets might be harmful or helpful to people trying to lose weight and improve their overall health, said Andrew Mente, a researcher at McMaster University in Hamilton, Canada, who wasn't involved in the study.

"Since there are no long-term trials of low-carb diets and health outcomes, this review is only able to report on intermediate risk markers rather than actual clinical outcome events like heart attacks, strokes, cardiovascular death, new diabetes events, and total mortality," Mente said by email.

While diets aren't one size fits all, most people should aim for a wide variety of healthy foods, said Dr. Sara Seidelmann, a cardiologist and nutritionist at Brigham and Women's Hospital and Harvard Medical School in Boston.

Ideally, adopt a diet full of plants and whole foods that provides overall cardio-protective qualities: rich in whole grains, vegetables, fruits, nuts, and legumes; eliminate processed foods and trans fats; limit refined grains, saturated fats, red meat and added sugars," Seidelmann, who wasn't involved in the study, said by email. "Adults that are interested in pursuing a very low or low carbohydrate diet for weight loss should consult with their clinician in order to weigh the risks and benefits of various diets and to share in the decision making process."

SOURCE: https://bit.ly/2nK56GL Journal of Clinical Lipidology, online September 13, 2019.

# data[].attributes.attachment_link.title
Low-carb 'keto' diets have some health benefits and some risks

# data[].attributes.attachment_link.description
Based on a review of existing research, the scientific statement emphasizes some advantages of a ketogenic, or very low-carb, diet including appetite suppression, lower lipid levels and lower blood sugar in people with diabetes. Over six months, people may lose more weight with popular low-carb diets

# data[].attributes.attachment_link.readable_text
By Lisa Rapaport

(Reuters Health) - While extremely low-carbohydrate diets may aid short term weight loss, they have mixed effects on health markers that can contribute to heart disease risk, according to new recommendations from the National Lipid Association.

Based on a review of existing research, the scientific statement emphasizes some advantages of a ketogenic, or very low-carb, diet including appetite suppression, lower lipid levels and lower blood sugar in people with diabetes.

But a keto diet is also associated with spikes in the "bad" cholesterol that can build up in blood vessels and lead to clots, known as low-density lipoprotein cholesterol (LDL-C).

Over six months, people may lose more weight with popular low-carb diets like the Atkins, ketogenic, South Beach, and Zone diets, according to the recommendations published in the Journal of Clinical Lipidology.

But after a year, weight loss with these diets is similar to what people can achieve with diets that allow more carbohydrates, according to the recommendations. Extremely low-carb diets can also be harder to stick with over time, and may severely restrict nutrient-dense foods that offer cardiovascular benefits, the recommendations stress.

There doesn't appear to be a meaningful difference between low-carb and other types of diets for other markers of cardiometabolic health like blood pressure.

"While some patients prefer a low-carbohydrate eating pattern, which may be reasonable for short periods of time, long-term compliance is challenging, and long-term benefits and risks are not fully understood, especially with ketogenic diets," said Carol Kirkpatrick, lead author of the recommendations and a researcher at Idaho State University in Pocatello.

With ketogenic diets, people typically eat very few carbs and consume a lot of fat, putting the body into a metabolic state known as ketosis. This can make the body more efficient at burning fat for energy and trigger reductions in blood sugar, previous research has found.

Some people on ketogenic diets have lost two to three times more weight than individuals with different eating habits, but much of this is based on short-term results.

"Weight loss with any dietary strategy is difficult and there are many factors that impact a person's ability to lose weight and maintain that weight loss," Kirkpatrick said by email. "Behavioral strategies, social support, and adequate physical activity have proven helpful for enhancing weight loss and helping with weight loss maintenance, no matter what type of weight loss diet is employed by a person needing to lose body fat."

People who might benefit from following an extremely low-carb diet for two to six months include individuals with diabetes and individuals with high levels of triglycerides in their blood, according to the recommendations.

Patients with a history of dangerously high cholesterol levels should avoid keto and extremely low-carb diets, the recommendations also note.

More research over longer periods of time is still needed to determine whether keto or low-carb diets might be harmful or helpful to people trying to lose weight and improve their overall health, said Andrew Mente, a researcher at McMaster University in Hamilton, Canada, who wasn't involved in the study.

"Since there are no long-term trials of low-carb diets and health outcomes, this review is only able to report on intermediate risk markers rather than actual clinical outcome events like heart attacks, strokes, cardiovascular death, new diabetes events, and total mortality," Mente said by email.

While diets aren't one size fits all, most people should aim for a wide variety of healthy foods, said Dr. Sara Seidelmann, a cardiologist and nutritionist at Brigham and Women's Hospital and Harvard Medical School in Boston.

Ideally, adopt a diet full of plants and whole foods that provides overall cardio-protective qualities: rich in whole grains, vegetables, fruits, nuts, and legumes; eliminate processed foods and trans fats; limit refined grains, saturated fats, red meat and added sugars," Seidelmann, who wasn't involved in the study, said by email. "Adults that are interested in pursuing a very low or low carbohydrate diet for weight loss should consult with their clinician in order to weigh the risks and benefits of various diets and to share in the decision making process."

SOURCE: https://bit.ly/2nK56GL Journal of Clinical Lipidology, online September 13, 2019.

# data[].attributes.attachment_link.title
Low-carb 'keto' diets have some health benefits and some risks

# data[].attributes.attachment_link.description
Based on a review of existing research, the scientific statement emphasizes some advantages of a ketogenic, or very low-carb, diet including appetite suppression, lower lipid levels and lower blood sugar in people with diabetes. Over six months, people may lose more weight with popular low-carb diets

# data[].attributes.attachment_link.readable_text
By Lisa Rapaport

(Reuters Health) - While extremely low-carbohydrate diets may aid short term weight loss, they have mixed effects on health markers that can contribute to heart disease risk, according to new recommendations from the National Lipid Association.

Based on a review of existing research, the scientific statement emphasizes some advantages of a ketogenic, or very low-carb, diet including appetite suppression, lower lipid levels and lower blood sugar in people with diabetes.

But a keto diet is also associated with spikes in the "bad" cholesterol that can build up in blood vessels and lead to clots, known as low-density lipoprotein cholesterol (LDL-C).

Over six months, people may lose more weight with popular low-carb diets like the Atkins, ketogenic, South Beach, and Zone diets, according to the recommendations published in the Journal of Clinical Lipidology.

But after a year, weight loss with these diets is similar to what people can achieve with diets that allow more carbohydrates, according to the recommendations. Extremely low-carb diets can also be harder to stick with over time, and may severely restrict nutrient-dense foods that offer cardiovascular benefits, the recommendations stress.

There doesn't appear to be a meaningful difference between low-carb and other types of diets for other markers of cardiometabolic health like blood pressure.

"While some patients prefer a low-carbohydrate eating pattern, which may be reasonable for short periods of time, long-term compliance is challenging, and long-term benefits and risks are not fully understood, especially with ketogenic diets," said Carol Kirkpatrick, lead author of the recommendations and a researcher at Idaho State University in Pocatello.

With ketogenic diets, people typically eat very few carbs and consume a lot of fat, putting the body into a metabolic state known as ketosis. This can make the body more efficient at burning fat for energy and trigger reductions in blood sugar, previous research has found.

Some people on ketogenic diets have lost two to three times more weight than individuals with different eating habits, but much of this is based on short-term results.

"Weight loss with any dietary strategy is difficult and there are many factors that impact a person's ability to lose weight and maintain that weight loss," Kirkpatrick said by email. "Behavioral strategies, social support, and adequate physical activity have proven helpful for enhancing weight loss and helping with weight loss maintenance, no matter what type of weight loss diet is employed by a person needing to lose body fat."

People who might benefit from following an extremely low-carb diet for two to six months include individuals with diabetes and individuals with high levels of triglycerides in their blood, according to the recommendations.

Patients with a history of dangerously high cholesterol levels should avoid keto and extremely low-carb diets, the recommendations also note.

More research over longer periods of time is still needed to determine whether keto or low-carb diets might be harmful or helpful to people trying to lose weight and improve their overall health, said Andrew Mente, a researcher at McMaster University in Hamilton, Canada, who wasn't involved in the study.

"Since there are no long-term trials of low-carb diets and health outcomes, this review is only able to report on intermediate risk markers rather than actual clinical outcome events like heart attacks, strokes, cardiovascular death, new diabetes events, and total mortality," Mente said by email.

While diets aren't one size fits all, most people should aim for a wide variety of healthy foods, said Dr. Sara Seidelmann, a cardiologist and nutritionist at Brigham and Women's Hospital and Harvard Medical School in Boston.

Ideally, adopt a diet full of plants and whole foods that provides overall cardio-protective qualities: rich in whole grains, vegetables, fruits, nuts, and legumes; eliminate processed foods and trans fats; limit refined grains, saturated fats, red meat and added sugars," Seidelmann, who wasn't involved in the study, said by email. "Adults that are interested in pursuing a very low or low carbohydrate diet for weight loss should consult with their clinician in order to weigh the risks and benefits of various diets and to share in the decision making process."

SOURCE: https://bit.ly/2nK56GL Journal of Clinical Lipidology, online September 13, 2019.

# data[].attributes.attachment_link.title
Low-carb 'keto' diets have some health benefits and some risks

# data[].attributes.attachment_link.description
Based on a review of existing research, the scientific statement emphasizes some advantages of a ketogenic, or very low-carb, diet including appetite suppression, lower lipid levels and lower blood sugar in people with diabetes. Over six months, people may lose more weight with popular low-carb diets

# data[].attributes.attachment_link.readable_text
Helen Truby, senior lecturer in nutrition and dietetics, ¹ Sue Baic, lecturer in nutrition, ² Anne deLooy, professor of dietetics, ³ Kenneth R Fox, professor of exercise science, ² M Barbara E Livingstone, professor of nutrition, ⁴ Catherine M Logan, PhD student, ⁴ Ian A Macdonald, professor, ⁵ Linda M Morgan, professor of nutritional endocrinology, ¹ Moira A Taylor, lecturer in nutrition and dietetics, ⁵ and D Joe Millward, professor of human nutrition ¹

Abstract

Objective To compare the effectiveness of four commercial weight loss diets available to adults in the United Kingdom.

Design Six month multicentre randomised unblinded controlled trial.

Setting Community based sample of otherwise healthy overweight and obese adults.

Interventions Dr Atkins' new diet revolution, Slim-Fast plan, Weight Watchers pure points programme, and Rosemary Conley's eat yourself slim diet and fitness plan.

Main outcome measures Weight and body fat changes over six months.

Results All diets resulted in significant loss of body fat and weight over six months. Groups did not differ significantly but loss of body fat and weight was greater in all groups compared with the control group. In an intention to treat analysis, average weight loss was 5.9 kg and average fat loss was 4.4 kg over six months. The Atkins diet resulted in significantly higher weight loss during the first four weeks, but by the end was no more or less effective than the other diets.

Conclusions Clinically useful weight loss and fat loss can be achieved in adults who are motivated to follow commercial diets for a substantial period. Given the limited resources for weight management in the NHS, healthcare practitioners should discuss with their patients programmes known to be effective.

Trial registration Clinical trials NCT00327821.

Introduction

The prevalence of obesity and its comorbidities is increasing in the United Kingdom. Over half of British adults are now overweight, and half of these people will probably become obese. The estimated cost of obesity is £0.5bn (€0.7bn; $0.9bn) each year to the NHS and £2bn each year to the wider economy.

Most adults in the United States diet at some time, and trends in the UK are similar.⁻ Long term success rates tend to be poor, with 50% of weight loss being regained within one year.

With a market estimated to be worth £11.2bn by 2007, it is not surprising that the commercial sector has shown a keen interest in weight loss programmes. Weight Watchers, the market leader, claims to have one million members (P Hunt, personal communication, 2005). Self help books that provide weight loss strategies are often best sellers- Dr Atkins' New Diet Revolution has sold more than 10 million copies. Although commercial diets provide consumers with a plethora of choice, data on their comparative efficacy are limited.

Our study compared four popular commercial weight loss programmes with a control group. The diets-representative of the main approaches to weight management in the UK today-were the Slim-Fast plan (a meal replacement approach), Weight Watchers pure points programme (an energy controlled diet with weekly group meetings), Dr Atkins' new diet revolution (a self monitored low carbohydrate eating plan), and Rosemary Conley's eat yourself slim diet and fitness plan (a low fat diet and a weekly group exercise class). We report the changes in weight and body fat over the six month study and describe dieting behaviour and weight change in the participants at 12 months.

Methods

The trial was an unblinded randomised controlled parallel dietary intervention study with a delayed treatment control group conducted at five regional centres (Surrey University, Bristol University, Nottingham University, Ulster (Coleraine) University, and Queen Margaret University College, Edinburgh).

Recruitment strategy

We identified potential participants via a BBC advertising campaign (television and other forms of media). Participants were chosen from people who lived within 30 miles of a test centre, were aged between 18 and 65, and had a self reported body mass index between 27 and 40. Volunteers who fulfilled these preliminary inclusion criteria contacted their general practitioner for confirmation that they were eligible. Exclusion criteria were coronary heart disease; type 1 or type 2 diabetes; renal, liver, or respiratory failure; gout; obesity with known cause (Cushing's disease, hypothyroidism); previous gastric or weight loss surgery; clinical depression; eating disorders; drug or alcohol misuse; any malabsorptive state (including lactose intolerance); taking lipid lowering or anti-hypertensive drugs; taking any drugs (including orlistat and sibutramine) for weight loss; being treated for cancer; and being pregnant or breastfeeding. Participants gave full informed consent. Three hundred people returned the necessary documentation to enter baseline testing by the start date of the study (July 2002).

Protocol assignment

We estimated that 60 initial participants (44 completers) were needed per treatment group (allowing for a 25% dropout rate) for an 80% chance of identifying a true difference of 4 kg of body weight loss (3 kg body fat), with a significance level of 5%. Thus, each of the five test centres aimed to recruit 60 participants (12 for each diet group; total sample size of 300). Participants took all baseline tests before randomisation and each centre started the study within six weeks of the start date. Seven participants were subsequently excluded (). At each test centre, we stratified participants by sex and allocated them to a group using random number generation. Body mass index and age did not differ between groups or between centres.

It was not possible to blind the participants to the diet regimen and we did not attempt to blind the investigators during the study or data analysis.

Providing dietary programmes to participants

For the group based programmes (Weight Watchers and Rosemary Conley), participants attended the most convenient class and we reimbursed the costs of joining and attending one class each week. Both parent companies signed a contract committing to the provision of standard care. For Slim-Fast, we reimbursed the cost of up to two meal replacements each day and provided a copy of the Slim-Fast support pack. We gave participants in the Atkins group a copy of Dr Atkins' New Diet Revolution. We asked the members of the control group to maintain their current diet and exercise pattern and offered them any of the diets for six months at the end of study (free of charge). All participants could claim reimbursement of travel costs.

Study protocol and monitoring

Measures at baseline, two months, and six months included weight, height, waist circumference, blood pressure, and fasting blood and body fat by whole body dual x ray absorptiometry. We excluded the absorptiometry data of four participants from all analyses because of errors at baseline. Monthly test centre measurements recorded weight in light clothing, blood pressure, and waist circumference. We monitored renal function in the Atkins group by urea, electrolytes, and cystatin C, and these measures remained within the reference ranges. Participants completed a seven day diet and activity diary at baseline, eight weeks, and 24 weeks. We gave no dietary or exercise advice so as not to compromise the study. When we analysed the food diaries at two months we found that some of the participants on the Atkins diet were not taking supplements of micronutrients as advised in the book. Therefore, from week 10 we offered free daily supplements of multivitamins. All participants who withdrew completed a short exit questionnaire. At 12 months, we recorded the weight and dieting behaviour from six to 12 months of all participants still willing to attend test centres.

Statistical analysis

The primary analysis was on an intention to treat basis, with baseline values carried forward to replace missing values (one participant was not used in this analysis as she withdrew because of pregnancy). A secondary analysis focused on the outcomes of these dietary approaches in the most motivated subjects who provided complete data (baseline, two months, and six months). Analysis of variance showed that the test centre did not affect total weight loss in participants who completed. Attrition rates did not differ between centres, so we analysed data from all participants together. Baseline weight correlated with total weight loss ( r = 0.33, P < 0.001) and was therefore used as a covariate in the analysis of weight loss over time, which uses repeated measures analysis of covariance. In the intention to treat analysis, we used ANOVA to examine differences between groups; where ANOVA indicated a significant group effect, we performed post hoc pairwise testing with Tukey's HSD (honestly significantly different) test. Before parametric testing, we assessed homogeneity of variance with Levene's statistic and tested for normal distribution; we used Welch's F statistic if variance of the dependent variable was not equal across groups. We analysed differences between participants who completed and withdrew with t tests for continuous variables (such as age) and χ ² for categorical variables (such as sex and diet group).

Results

shows the baseline demographics and anthropometric measures. The mean time spent on the diet was 24.3 (SD 1.56) weeks and did not differ between diet groups ( F = 2.0, P = 0.12).

Table 1

Weight and fat loss

Monthly weight loss by using all available data () was high initially but then slowed. Mean weight loss was significantly higher in the Atkins group than in the other diet groups during the first four weeks ( F = 6.9, df = 3, P < 0.001): Atkins 4.4 kg (SD 2.45, range 13.5 to 0.3 kg), Weight Watchers 2.86 kg (2.23, 12.9 to - 0.9 kg), Slim-Fast 2.68 kg (2.33, 9.4 to - 1.8 kg), and Rosemary Conley 3.17 kg (2.02, 8.1 to - 2.0 kg). At other time points, mean weight loss did not vary significantly between the diet groups ().

Table 2

Loss of body fat showed similar patterns (). In the first two months, the greatest loss of body fat was seen in the Atkins group; this loss was not significantly different from that seen in the Weight Watchers or Rosemary Conley groups, but it was significantly greater than that seen in the Slim-Fast group. Fat loss was significantly greater in all four diet groups than in the control group. Between two and six months, fat loss (kg and percentage) slowed down, and the diets groups did not differ significantly. Between baseline and six months fat loss did not differ between diet groups, but fat loss in all diet groups was significantly greater than in the control group. All diets resulted in a reduction in waist circumference. Waist reduction (at six months) was highly correlated with total weight loss ( r = 0.81, P < 0.001) and moderately correlated with percentage of body fat lost ( r = 0.64, P < 0.001).

Cardiac risk factors

We found few significant differences in cardiac risk factors between the diets groups and the control group (). Initially, the fall in systolic pressure in the Atkins group was significantly greater than in the Slim-Fast group but not the other groups, probably because of the relatively greater initial weight loss in the Atkins group. Regression analysis showed that total weight loss over time had the greatest influence on systolic and diastolic pressure (adjusted R ² 0.61 for change in systolic pressure and 0.79 for change in diastolic pressure).

Table 3

Glucose concentrations fell slightly over time; only in the Weight Watchers group was fasting glucose significantly lower than in the control group. In the first two months, a significant but small drop in total cholesterol was seen in all diet groups except for the Atkins group. By six months, cholesterol had fallen significantly compared with the control group only in the Weight Watchers group (by 0.55 mmol/l).

Analysis of completers

A secondary analysis of data from participants who completed the trial shows the range of weight lost by these highly motivated participants, who probably adhered most strongly to the randomly allocated diets. shows the range of total weight lost; some participants lost more than 25 kg over the six month study period, whereas others gained weight ().

After six months all diets resulted in a clinically useful mean reduction in percentage body weight: Rosemary Conley 9.9% (SD 5.6%), Weight Watchers 9.0% (5.6%), Atkins 8.9% (5.6%), and Slim-Fast 6.8% (5.3%); no significant differences were seen between the diets but all were more successful than no diet (controls gained 0.95%, 3.3%). The proportion of participants who completed the trial and lost at least 10% of their body weight at six months was 46% for the Rosemary Conley group, 45% for the Atkins group, 36% for the Weight Watchers group, and 21% for the Slim-Fast group. These losses were achieved despite the random allocation of diets.

Compliance with the diets

Reported attendance at slimming clubs was similar at two months (Rosemary Conley 79%, Weight Watchers 66%) and six months (47%, 47%). Slim-Fast recommends 14 meal replacements each week; participants reported 10 each week at two months and eight at six months. With the Atkins diet, reported portions of carbohydrate foods fell from 40 each day at baseline to five at two months and seven at six months.

Withdrawal

Eighty three (28%) participants had withdrawn by six months (); 53 (64% of the total number) had withdrawn by week 8, and at this time only seven (8%) participants who withdrew had lost more than 5% of their body weight compared with 53 (25%) who completed the trial. Older participants were significantly more likely to complete than younger ones (mean age 41.6 (9.9) v 36.8 (10.4); t = - 3.7, P < 0.001; 95% confidence interval 2.3 to 7.4). No differences in diet, centre, or sex were found between participants who completed or withdrew. Withdrawal in the control group (21; 35%) was mostly because participants did not wish to delay dieting.

Table 4

Follow-up at 12 months

At 12 months, 158 participants (54% of the original sample) returned data; 29 had originally been allocated to the Atkins diet, 33 to Weight Watchers, 33 to Slim-Fast, 35 to Rosemary Conley, and 28 to the control group. Dieting behaviour had changed considerably: only 58 (45%) were still keeping to their originally allocated diets (nine to Atkins, 20 to Weight Watchers, nine to Slim-Fast, 20 to Rosemary Conley). Twenty five (19%) had swapped dietary programmes and 47 (36%) were following their own diet or exercise plan. More participants in the unsupported programmes (Atkins diet and Slim-Fast) withdrew than in the supported programmes (χ ² = 8.34, df = 3.0, P = 0.04). Participants in the control group who had switched to dieting (mean weight loss 6.37, SD 4.5 kg) also preferred group based approaches because just over half chose Weight Watchers.

Because so many participants changed diets (25% of men and 29% of women), we also analysed weight loss in participants who had maintained the diet to which they were initially allocated (). Statistical analysis is limited by sample size but indicates that weight rebound after the initial six months was higher in the unsupported programmes; however, all diets resulted in a clinically useful weight loss of around 10% after 12 months in participants who had persisted with the diet allocated.

Table 5

Discussion

Clinically beneficial weight loss is possible through commercially available strategies, and reduced blood pressure and waist circumference accompany weight loss. The four different approaches were equally effective after six months. Reductions in weight and body fat were seen with the Atkins diet within the first eight weeks of dieting, so that the large weight changes seen with low carbohydrate diets are not caused by loss of body water alone. The Atkins diet had no detrimental effects on total cholesterol concentrations or renal function, although the overall safety of the diet was not tested.

The range of absolute weight loss in participants who completed the study was wide. Importantly, we did not try to standardise energy intake across the groups, so that the effects reflect the participants' interpretation of and compliance with the diet allocated. However, the mean absolute weight loss of around 8 kg is comparable to other studies. Compliance with each diet varied greatly. Weight can be lost only by a sustained negative balance of energy, so the degree of adherence to a diet will predict success or failure if activity levels remain constant. More information is needed to enable health professionals to decide which dietary approach may suit their patients. Currently, we cannot predict the dietary approach best suited to each person to lose weight and maintain weight loss in the longer term, but it is clear that "one size does not fit all."

Our study was used to make the BBC series on diet trials, which featured a small number of people. Since motivation to meet goal weights and patients' expectations of weight loss are key determinants of success, participants may have been influenced by the media interest. Overall, around 5% of participants were featured in the television programmes, and most participants knew that they would not be filmed within the first few weeks. Excluding data from the 15 filmed participants had no effect on the overall statistical outcomes shown in this study. The withdrawal rate was comparable to other longitudinal studies of weight loss.⁻

No dietary differences were apparent at six months, but behaviour from six to 12 months points towards an advantage of programmes based on group support. The need for a "quick fix" and the relative lack of interest that people show in achieving modest weight loss contribute to lack of adherence to most diets in the long term. People who had kept to their allocated diet lost about 10% of their weight, despite some weight rebound, but some regression to the mean effect was seen. These results provide information on the "best effect" that the most highly motivated subjects may hope to achieve over one year.

In conclusion, commercial weight loss programmes can help people with uncomplicated obesity. Our study provides data on how much weight patients can expect to lose by dieting, and these data could help practitioners in managing patients' some-times unrealistic expectations of weight loss targets. The benefits to health of modest weight loss and maintaining that loss over long periods need to be emphasised.
What is already known about this topic
The prevalence of obesity and overweight with its subsequent comorbidities is growing in the UK

Commercial diets are an increasingly popular option for weight management
What this study adds
The comparative efficacy of four commercial diets was similar

The health benefits associated with a modest loss of weight (5-10% body weight) can be gained by people following a range of dietary regimens for six months with little support from health professionals

Notes

Contributors: HT was the principal investigator and is guarantor. She contributed to the study design, data analysis, interpretation, drafting, and writing of the paper. DJM and LMM contributed to the study design, data analysis, interpretation, drafting, and writing of the paper. KRF contributed to the study design, interpretation, reporting, and critical review of paper. SB contributed to study execution, data collection, and critical review of the paper. IAM, MAT, MBEL, CML, and AdeL contributed to the study planning, interpretation, reporting, and critical review of the paper. Thanks to David Lovell for statistical advice; Manana Stanley, Rebecca Hiscutt, and Anne Herriot for planning, study execution, and data collection; Monique Raats and Richard Shepherd for study planning; Kathryn Hart, Rachel Barratt, Karen Sargent, Sarah Jones, Julie Littlewood, Sujata Dissanayake, Elizabeth Simpson, and Michelle Hazell for data collection; Mark Davis for study design and data collection; Katherine Collings for planning, study execution, and data collection; Paula J Robson, Julie MW Wallace, Maxine P Bonham, and Laura Nichol for study execution and data collection; Susan Jebb for study design; and Kirsten Rennie for sample size determination.

Competing interests: KRF receives consulting fees for serving on the scientific advisory panel of Slimming World, a company that offers a support service for weight loss. This company was not involved in this trial but as it is similar to Rosemary Conley and Weight Watchers, the conclusions may have implications for the company.

Funding: The study was sponsored by the BBC. The BBC had no role in the study design; collection, analysis, or interpretation of data; or report writing.

Ethical approval: South East multicentre research ethics committee, approval number MREC 01/01/44. Local ethics committee approval was also obtained at each centre.

References

1. Department of Health. White paper on public health. Saving lives: our healthier nation. London: Stationery Office, 1999.

2. Royal College of Physicians. Storing up problems: the medical case for a slimmer nation. London: RCP, 2004. [ PMC free article] [ PubMed]

7. Perri MG. The maintenance of treatment effects in the long term management of obesity. Clin Psychol Sci Pract 1998;5: 526-43. [ Google Scholar]

8. Atkins R. Dr Atkins' new diet revolution. South Dakota: Vermillion, 1999.

# data[].attributes.attachment_link.title
Randomised controlled trial of four commercial weight loss programmes in the UK: initial findings from the BBC "diet trials"

# data[].attributes.attachment_link.description
Helen Truby, senior lecturer in nutrition and dietetics, 1 Sue Baic, lecturer in nutrition, 2 Anne deLooy, professor of dietetics, 3 Kenneth R Fox, professor of exercise science, 2 M Barbara E Livingstone, professor of nutrition, 4 Catherine M Logan, PhD student, 4 Ian A Macdonald, professor, 5 Linda M Morgan, professor of nutritional endocrinology, 1 Moira A Taylor, lecturer in nutrition and dietetics, 5 and D Joe Millward, professor of human nutrition 1 Objective To compare the effectiveness of four commercial weight loss diets available to adults in the United Kingdom.

# data[].attributes.attachment_link.readable_text
Helen Truby, senior lecturer in nutrition and dietetics, ¹ Sue Baic, lecturer in nutrition, ² Anne deLooy, professor of dietetics, ³ Kenneth R Fox, professor of exercise science, ² M Barbara E Livingstone, professor of nutrition, ⁴ Catherine M Logan, PhD student, ⁴ Ian A Macdonald, professor, ⁵ Linda M Morgan, professor of nutritional endocrinology, ¹ Moira A Taylor, lecturer in nutrition and dietetics, ⁵ and D Joe Millward, professor of human nutrition ¹

Abstract

Objective To compare the effectiveness of four commercial weight loss diets available to adults in the United Kingdom.

Design Six month multicentre randomised unblinded controlled trial.

Setting Community based sample of otherwise healthy overweight and obese adults.

Interventions Dr Atkins' new diet revolution, Slim-Fast plan, Weight Watchers pure points programme, and Rosemary Conley's eat yourself slim diet and fitness plan.

Main outcome measures Weight and body fat changes over six months.

Results All diets resulted in significant loss of body fat and weight over six months. Groups did not differ significantly but loss of body fat and weight was greater in all groups compared with the control group. In an intention to treat analysis, average weight loss was 5.9 kg and average fat loss was 4.4 kg over six months. The Atkins diet resulted in significantly higher weight loss during the first four weeks, but by the end was no more or less effective than the other diets.

Conclusions Clinically useful weight loss and fat loss can be achieved in adults who are motivated to follow commercial diets for a substantial period. Given the limited resources for weight management in the NHS, healthcare practitioners should discuss with their patients programmes known to be effective.

Trial registration Clinical trials NCT00327821.

Introduction

The prevalence of obesity and its comorbidities is increasing in the United Kingdom. Over half of British adults are now overweight, and half of these people will probably become obese. The estimated cost of obesity is £0.5bn (€0.7bn; $0.9bn) each year to the NHS and £2bn each year to the wider economy.

Most adults in the United States diet at some time, and trends in the UK are similar.⁻ Long term success rates tend to be poor, with 50% of weight loss being regained within one year.

With a market estimated to be worth £11.2bn by 2007, it is not surprising that the commercial sector has shown a keen interest in weight loss programmes. Weight Watchers, the market leader, claims to have one million members (P Hunt, personal communication, 2005). Self help books that provide weight loss strategies are often best sellers- Dr Atkins' New Diet Revolution has sold more than 10 million copies. Although commercial diets provide consumers with a plethora of choice, data on their comparative efficacy are limited.

Our study compared four popular commercial weight loss programmes with a control group. The diets-representative of the main approaches to weight management in the UK today-were the Slim-Fast plan (a meal replacement approach), Weight Watchers pure points programme (an energy controlled diet with weekly group meetings), Dr Atkins' new diet revolution (a self monitored low carbohydrate eating plan), and Rosemary Conley's eat yourself slim diet and fitness plan (a low fat diet and a weekly group exercise class). We report the changes in weight and body fat over the six month study and describe dieting behaviour and weight change in the participants at 12 months.

Methods

The trial was an unblinded randomised controlled parallel dietary intervention study with a delayed treatment control group conducted at five regional centres (Surrey University, Bristol University, Nottingham University, Ulster (Coleraine) University, and Queen Margaret University College, Edinburgh).

Recruitment strategy

We identified potential participants via a BBC advertising campaign (television and other forms of media). Participants were chosen from people who lived within 30 miles of a test centre, were aged between 18 and 65, and had a self reported body mass index between 27 and 40. Volunteers who fulfilled these preliminary inclusion criteria contacted their general practitioner for confirmation that they were eligible. Exclusion criteria were coronary heart disease; type 1 or type 2 diabetes; renal, liver, or respiratory failure; gout; obesity with known cause (Cushing's disease, hypothyroidism); previous gastric or weight loss surgery; clinical depression; eating disorders; drug or alcohol misuse; any malabsorptive state (including lactose intolerance); taking lipid lowering or anti-hypertensive drugs; taking any drugs (including orlistat and sibutramine) for weight loss; being treated for cancer; and being pregnant or breastfeeding. Participants gave full informed consent. Three hundred people returned the necessary documentation to enter baseline testing by the start date of the study (July 2002).

Protocol assignment

We estimated that 60 initial participants (44 completers) were needed per treatment group (allowing for a 25% dropout rate) for an 80% chance of identifying a true difference of 4 kg of body weight loss (3 kg body fat), with a significance level of 5%. Thus, each of the five test centres aimed to recruit 60 participants (12 for each diet group; total sample size of 300). Participants took all baseline tests before randomisation and each centre started the study within six weeks of the start date. Seven participants were subsequently excluded (). At each test centre, we stratified participants by sex and allocated them to a group using random number generation. Body mass index and age did not differ between groups or between centres.

It was not possible to blind the participants to the diet regimen and we did not attempt to blind the investigators during the study or data analysis.

Providing dietary programmes to participants

For the group based programmes (Weight Watchers and Rosemary Conley), participants attended the most convenient class and we reimbursed the costs of joining and attending one class each week. Both parent companies signed a contract committing to the provision of standard care. For Slim-Fast, we reimbursed the cost of up to two meal replacements each day and provided a copy of the Slim-Fast support pack. We gave participants in the Atkins group a copy of Dr Atkins' New Diet Revolution. We asked the members of the control group to maintain their current diet and exercise pattern and offered them any of the diets for six months at the end of study (free of charge). All participants could claim reimbursement of travel costs.

Study protocol and monitoring

Measures at baseline, two months, and six months included weight, height, waist circumference, blood pressure, and fasting blood and body fat by whole body dual x ray absorptiometry. We excluded the absorptiometry data of four participants from all analyses because of errors at baseline. Monthly test centre measurements recorded weight in light clothing, blood pressure, and waist circumference. We monitored renal function in the Atkins group by urea, electrolytes, and cystatin C, and these measures remained within the reference ranges. Participants completed a seven day diet and activity diary at baseline, eight weeks, and 24 weeks. We gave no dietary or exercise advice so as not to compromise the study. When we analysed the food diaries at two months we found that some of the participants on the Atkins diet were not taking supplements of micronutrients as advised in the book. Therefore, from week 10 we offered free daily supplements of multivitamins. All participants who withdrew completed a short exit questionnaire. At 12 months, we recorded the weight and dieting behaviour from six to 12 months of all participants still willing to attend test centres.

Statistical analysis

The primary analysis was on an intention to treat basis, with baseline values carried forward to replace missing values (one participant was not used in this analysis as she withdrew because of pregnancy). A secondary analysis focused on the outcomes of these dietary approaches in the most motivated subjects who provided complete data (baseline, two months, and six months). Analysis of variance showed that the test centre did not affect total weight loss in participants who completed. Attrition rates did not differ between centres, so we analysed data from all participants together. Baseline weight correlated with total weight loss ( r = 0.33, P < 0.001) and was therefore used as a covariate in the analysis of weight loss over time, which uses repeated measures analysis of covariance. In the intention to treat analysis, we used ANOVA to examine differences between groups; where ANOVA indicated a significant group effect, we performed post hoc pairwise testing with Tukey's HSD (honestly significantly different) test. Before parametric testing, we assessed homogeneity of variance with Levene's statistic and tested for normal distribution; we used Welch's F statistic if variance of the dependent variable was not equal across groups. We analysed differences between participants who completed and withdrew with t tests for continuous variables (such as age) and χ ² for categorical variables (such as sex and diet group).

Results

shows the baseline demographics and anthropometric measures. The mean time spent on the diet was 24.3 (SD 1.56) weeks and did not differ between diet groups ( F = 2.0, P = 0.12).

Table 1

Weight and fat loss

Monthly weight loss by using all available data () was high initially but then slowed. Mean weight loss was significantly higher in the Atkins group than in the other diet groups during the first four weeks ( F = 6.9, df = 3, P < 0.001): Atkins 4.4 kg (SD 2.45, range 13.5 to 0.3 kg), Weight Watchers 2.86 kg (2.23, 12.9 to - 0.9 kg), Slim-Fast 2.68 kg (2.33, 9.4 to - 1.8 kg), and Rosemary Conley 3.17 kg (2.02, 8.1 to - 2.0 kg). At other time points, mean weight loss did not vary significantly between the diet groups ().

Table 2

Loss of body fat showed similar patterns (). In the first two months, the greatest loss of body fat was seen in the Atkins group; this loss was not significantly different from that seen in the Weight Watchers or Rosemary Conley groups, but it was significantly greater than that seen in the Slim-Fast group. Fat loss was significantly greater in all four diet groups than in the control group. Between two and six months, fat loss (kg and percentage) slowed down, and the diets groups did not differ significantly. Between baseline and six months fat loss did not differ between diet groups, but fat loss in all diet groups was significantly greater than in the control group. All diets resulted in a reduction in waist circumference. Waist reduction (at six months) was highly correlated with total weight loss ( r = 0.81, P < 0.001) and moderately correlated with percentage of body fat lost ( r = 0.64, P < 0.001).

Cardiac risk factors

We found few significant differences in cardiac risk factors between the diets groups and the control group (). Initially, the fall in systolic pressure in the Atkins group was significantly greater than in the Slim-Fast group but not the other groups, probably because of the relatively greater initial weight loss in the Atkins group. Regression analysis showed that total weight loss over time had the greatest influence on systolic and diastolic pressure (adjusted R ² 0.61 for change in systolic pressure and 0.79 for change in diastolic pressure).

Table 3

Glucose concentrations fell slightly over time; only in the Weight Watchers group was fasting glucose significantly lower than in the control group. In the first two months, a significant but small drop in total cholesterol was seen in all diet groups except for the Atkins group. By six months, cholesterol had fallen significantly compared with the control group only in the Weight Watchers group (by 0.55 mmol/l).

Analysis of completers

A secondary analysis of data from participants who completed the trial shows the range of weight lost by these highly motivated participants, who probably adhered most strongly to the randomly allocated diets. shows the range of total weight lost; some participants lost more than 25 kg over the six month study period, whereas others gained weight ().

After six months all diets resulted in a clinically useful mean reduction in percentage body weight: Rosemary Conley 9.9% (SD 5.6%), Weight Watchers 9.0% (5.6%), Atkins 8.9% (5.6%), and Slim-Fast 6.8% (5.3%); no significant differences were seen between the diets but all were more successful than no diet (controls gained 0.95%, 3.3%). The proportion of participants who completed the trial and lost at least 10% of their body weight at six months was 46% for the Rosemary Conley group, 45% for the Atkins group, 36% for the Weight Watchers group, and 21% for the Slim-Fast group. These losses were achieved despite the random allocation of diets.

Compliance with the diets

Reported attendance at slimming clubs was similar at two months (Rosemary Conley 79%, Weight Watchers 66%) and six months (47%, 47%). Slim-Fast recommends 14 meal replacements each week; participants reported 10 each week at two months and eight at six months. With the Atkins diet, reported portions of carbohydrate foods fell from 40 each day at baseline to five at two months and seven at six months.

Withdrawal

Eighty three (28%) participants had withdrawn by six months (); 53 (64% of the total number) had withdrawn by week 8, and at this time only seven (8%) participants who withdrew had lost more than 5% of their body weight compared with 53 (25%) who completed the trial. Older participants were significantly more likely to complete than younger ones (mean age 41.6 (9.9) v 36.8 (10.4); t = - 3.7, P < 0.001; 95% confidence interval 2.3 to 7.4). No differences in diet, centre, or sex were found between participants who completed or withdrew. Withdrawal in the control group (21; 35%) was mostly because participants did not wish to delay dieting.

Table 4

Follow-up at 12 months

At 12 months, 158 participants (54% of the original sample) returned data; 29 had originally been allocated to the Atkins diet, 33 to Weight Watchers, 33 to Slim-Fast, 35 to Rosemary Conley, and 28 to the control group. Dieting behaviour had changed considerably: only 58 (45%) were still keeping to their originally allocated diets (nine to Atkins, 20 to Weight Watchers, nine to Slim-Fast, 20 to Rosemary Conley). Twenty five (19%) had swapped dietary programmes and 47 (36%) were following their own diet or exercise plan. More participants in the unsupported programmes (Atkins diet and Slim-Fast) withdrew than in the supported programmes (χ ² = 8.34, df = 3.0, P = 0.04). Participants in the control group who had switched to dieting (mean weight loss 6.37, SD 4.5 kg) also preferred group based approaches because just over half chose Weight Watchers.

Because so many participants changed diets (25% of men and 29% of women), we also analysed weight loss in participants who had maintained the diet to which they were initially allocated (). Statistical analysis is limited by sample size but indicates that weight rebound after the initial six months was higher in the unsupported programmes; however, all diets resulted in a clinically useful weight loss of around 10% after 12 months in participants who had persisted with the diet allocated.

Table 5

Discussion

Clinically beneficial weight loss is possible through commercially available strategies, and reduced blood pressure and waist circumference accompany weight loss. The four different approaches were equally effective after six months. Reductions in weight and body fat were seen with the Atkins diet within the first eight weeks of dieting, so that the large weight changes seen with low carbohydrate diets are not caused by loss of body water alone. The Atkins diet had no detrimental effects on total cholesterol concentrations or renal function, although the overall safety of the diet was not tested.

The range of absolute weight loss in participants who completed the study was wide. Importantly, we did not try to standardise energy intake across the groups, so that the effects reflect the participants' interpretation of and compliance with the diet allocated. However, the mean absolute weight loss of around 8 kg is comparable to other studies. Compliance with each diet varied greatly. Weight can be lost only by a sustained negative balance of energy, so the degree of adherence to a diet will predict success or failure if activity levels remain constant. More information is needed to enable health professionals to decide which dietary approach may suit their patients. Currently, we cannot predict the dietary approach best suited to each person to lose weight and maintain weight loss in the longer term, but it is clear that "one size does not fit all."

Our study was used to make the BBC series on diet trials, which featured a small number of people. Since motivation to meet goal weights and patients' expectations of weight loss are key determinants of success, participants may have been influenced by the media interest. Overall, around 5% of participants were featured in the television programmes, and most participants knew that they would not be filmed within the first few weeks. Excluding data from the 15 filmed participants had no effect on the overall statistical outcomes shown in this study. The withdrawal rate was comparable to other longitudinal studies of weight loss.⁻

No dietary differences were apparent at six months, but behaviour from six to 12 months points towards an advantage of programmes based on group support. The need for a "quick fix" and the relative lack of interest that people show in achieving modest weight loss contribute to lack of adherence to most diets in the long term. People who had kept to their allocated diet lost about 10% of their weight, despite some weight rebound, but some regression to the mean effect was seen. These results provide information on the "best effect" that the most highly motivated subjects may hope to achieve over one year.

In conclusion, commercial weight loss programmes can help people with uncomplicated obesity. Our study provides data on how much weight patients can expect to lose by dieting, and these data could help practitioners in managing patients' some-times unrealistic expectations of weight loss targets. The benefits to health of modest weight loss and maintaining that loss over long periods need to be emphasised.
What is already known about this topic
The prevalence of obesity and overweight with its subsequent comorbidities is growing in the UK

Commercial diets are an increasingly popular option for weight management
What this study adds
The comparative efficacy of four commercial diets was similar

The health benefits associated with a modest loss of weight (5-10% body weight) can be gained by people following a range of dietary regimens for six months with little support from health professionals

Notes

Contributors: HT was the principal investigator and is guarantor. She contributed to the study design, data analysis, interpretation, drafting, and writing of the paper. DJM and LMM contributed to the study design, data analysis, interpretation, drafting, and writing of the paper. KRF contributed to the study design, interpretation, reporting, and critical review of paper. SB contributed to study execution, data collection, and critical review of the paper. IAM, MAT, MBEL, CML, and AdeL contributed to the study planning, interpretation, reporting, and critical review of the paper. Thanks to David Lovell for statistical advice; Manana Stanley, Rebecca Hiscutt, and Anne Herriot for planning, study execution, and data collection; Monique Raats and Richard Shepherd for study planning; Kathryn Hart, Rachel Barratt, Karen Sargent, Sarah Jones, Julie Littlewood, Sujata Dissanayake, Elizabeth Simpson, and Michelle Hazell for data collection; Mark Davis for study design and data collection; Katherine Collings for planning, study execution, and data collection; Paula J Robson, Julie MW Wallace, Maxine P Bonham, and Laura Nichol for study execution and data collection; Susan Jebb for study design; and Kirsten Rennie for sample size determination.

Competing interests: KRF receives consulting fees for serving on the scientific advisory panel of Slimming World, a company that offers a support service for weight loss. This company was not involved in this trial but as it is similar to Rosemary Conley and Weight Watchers, the conclusions may have implications for the company.

Funding: The study was sponsored by the BBC. The BBC had no role in the study design; collection, analysis, or interpretation of data; or report writing.

Ethical approval: South East multicentre research ethics committee, approval number MREC 01/01/44. Local ethics committee approval was also obtained at each centre.

References

1. Department of Health. White paper on public health. Saving lives: our healthier nation. London: Stationery Office, 1999.

2. Royal College of Physicians. Storing up problems: the medical case for a slimmer nation. London: RCP, 2004. [ PMC free article] [ PubMed]

7. Perri MG. The maintenance of treatment effects in the long term management of obesity. Clin Psychol Sci Pract 1998;5: 526-43. [ Google Scholar]

8. Atkins R. Dr Atkins' new diet revolution. South Dakota: Vermillion, 1999.

# data[].attributes.attachment_link.title
Randomised controlled trial of four commercial weight loss programmes in the UK: initial findings from the BBC "diet trials"

# data[].attributes.attachment_link.description
Helen Truby, senior lecturer in nutrition and dietetics, 1 Sue Baic, lecturer in nutrition, 2 Anne deLooy, professor of dietetics, 3 Kenneth R Fox, professor of exercise science, 2 M Barbara E Livingstone, professor of nutrition, 4 Catherine M Logan, PhD student, 4 Ian A Macdonald, professor, 5 Linda M Morgan, professor of nutritional endocrinology, 1 Moira A Taylor, lecturer in nutrition and dietetics, 5 and D Joe Millward, professor of human nutrition 1 Objective To compare the effectiveness of four commercial weight loss diets available to adults in the United Kingdom.

# data[].attributes.attachment_link.readable_text
Helen Truby, senior lecturer in nutrition and dietetics, ¹ Sue Baic, lecturer in nutrition, ² Anne deLooy, professor of dietetics, ³ Kenneth R Fox, professor of exercise science, ² M Barbara E Livingstone, professor of nutrition, ⁴ Catherine M Logan, PhD student, ⁴ Ian A Macdonald, professor, ⁵ Linda M Morgan, professor of nutritional endocrinology, ¹ Moira A Taylor, lecturer in nutrition and dietetics, ⁵ and D Joe Millward, professor of human nutrition ¹

Abstract

Objective To compare the effectiveness of four commercial weight loss diets available to adults in the United Kingdom.

Design Six month multicentre randomised unblinded controlled trial.

Setting Community based sample of otherwise healthy overweight and obese adults.

Interventions Dr Atkins' new diet revolution, Slim-Fast plan, Weight Watchers pure points programme, and Rosemary Conley's eat yourself slim diet and fitness plan.

Main outcome measures Weight and body fat changes over six months.

Results All diets resulted in significant loss of body fat and weight over six months. Groups did not differ significantly but loss of body fat and weight was greater in all groups compared with the control group. In an intention to treat analysis, average weight loss was 5.9 kg and average fat loss was 4.4 kg over six months. The Atkins diet resulted in significantly higher weight loss during the first four weeks, but by the end was no more or less effective than the other diets.

Conclusions Clinically useful weight loss and fat loss can be achieved in adults who are motivated to follow commercial diets for a substantial period. Given the limited resources for weight management in the NHS, healthcare practitioners should discuss with their patients programmes known to be effective.

Trial registration Clinical trials NCT00327821.

Introduction

The prevalence of obesity and its comorbidities is increasing in the United Kingdom. Over half of British adults are now overweight, and half of these people will probably become obese. The estimated cost of obesity is £0.5bn (€0.7bn; $0.9bn) each year to the NHS and £2bn each year to the wider economy.

Most adults in the United States diet at some time, and trends in the UK are similar.⁻ Long term success rates tend to be poor, with 50% of weight loss being regained within one year.

With a market estimated to be worth £11.2bn by 2007, it is not surprising that the commercial sector has shown a keen interest in weight loss programmes. Weight Watchers, the market leader, claims to have one million members (P Hunt, personal communication, 2005). Self help books that provide weight loss strategies are often best sellers- Dr Atkins' New Diet Revolution has sold more than 10 million copies. Although commercial diets provide consumers with a plethora of choice, data on their comparative efficacy are limited.

Our study compared four popular commercial weight loss programmes with a control group. The diets-representative of the main approaches to weight management in the UK today-were the Slim-Fast plan (a meal replacement approach), Weight Watchers pure points programme (an energy controlled diet with weekly group meetings), Dr Atkins' new diet revolution (a self monitored low carbohydrate eating plan), and Rosemary Conley's eat yourself slim diet and fitness plan (a low fat diet and a weekly group exercise class). We report the changes in weight and body fat over the six month study and describe dieting behaviour and weight change in the participants at 12 months.

Methods

The trial was an unblinded randomised controlled parallel dietary intervention study with a delayed treatment control group conducted at five regional centres (Surrey University, Bristol University, Nottingham University, Ulster (Coleraine) University, and Queen Margaret University College, Edinburgh).

Recruitment strategy

We identified potential participants via a BBC advertising campaign (television and other forms of media). Participants were chosen from people who lived within 30 miles of a test centre, were aged between 18 and 65, and had a self reported body mass index between 27 and 40. Volunteers who fulfilled these preliminary inclusion criteria contacted their general practitioner for confirmation that they were eligible. Exclusion criteria were coronary heart disease; type 1 or type 2 diabetes; renal, liver, or respiratory failure; gout; obesity with known cause (Cushing's disease, hypothyroidism); previous gastric or weight loss surgery; clinical depression; eating disorders; drug or alcohol misuse; any malabsorptive state (including lactose intolerance); taking lipid lowering or anti-hypertensive drugs; taking any drugs (including orlistat and sibutramine) for weight loss; being treated for cancer; and being pregnant or breastfeeding. Participants gave full informed consent. Three hundred people returned the necessary documentation to enter baseline testing by the start date of the study (July 2002).

Protocol assignment

We estimated that 60 initial participants (44 completers) were needed per treatment group (allowing for a 25% dropout rate) for an 80% chance of identifying a true difference of 4 kg of body weight loss (3 kg body fat), with a significance level of 5%. Thus, each of the five test centres aimed to recruit 60 participants (12 for each diet group; total sample size of 300). Participants took all baseline tests before randomisation and each centre started the study within six weeks of the start date. Seven participants were subsequently excluded (). At each test centre, we stratified participants by sex and allocated them to a group using random number generation. Body mass index and age did not differ between groups or between centres.

It was not possible to blind the participants to the diet regimen and we did not attempt to blind the investigators during the study or data analysis.

Providing dietary programmes to participants

For the group based programmes (Weight Watchers and Rosemary Conley), participants attended the most convenient class and we reimbursed the costs of joining and attending one class each week. Both parent companies signed a contract committing to the provision of standard care. For Slim-Fast, we reimbursed the cost of up to two meal replacements each day and provided a copy of the Slim-Fast support pack. We gave participants in the Atkins group a copy of Dr Atkins' New Diet Revolution. We asked the members of the control group to maintain their current diet and exercise pattern and offered them any of the diets for six months at the end of study (free of charge). All participants could claim reimbursement of travel costs.

Study protocol and monitoring

Measures at baseline, two months, and six months included weight, height, waist circumference, blood pressure, and fasting blood and body fat by whole body dual x ray absorptiometry. We excluded the absorptiometry data of four participants from all analyses because of errors at baseline. Monthly test centre measurements recorded weight in light clothing, blood pressure, and waist circumference. We monitored renal function in the Atkins group by urea, electrolytes, and cystatin C, and these measures remained within the reference ranges. Participants completed a seven day diet and activity diary at baseline, eight weeks, and 24 weeks. We gave no dietary or exercise advice so as not to compromise the study. When we analysed the food diaries at two months we found that some of the participants on the Atkins diet were not taking supplements of micronutrients as advised in the book. Therefore, from week 10 we offered free daily supplements of multivitamins. All participants who withdrew completed a short exit questionnaire. At 12 months, we recorded the weight and dieting behaviour from six to 12 months of all participants still willing to attend test centres.

Statistical analysis

The primary analysis was on an intention to treat basis, with baseline values carried forward to replace missing values (one participant was not used in this analysis as she withdrew because of pregnancy). A secondary analysis focused on the outcomes of these dietary approaches in the most motivated subjects who provided complete data (baseline, two months, and six months). Analysis of variance showed that the test centre did not affect total weight loss in participants who completed. Attrition rates did not differ between centres, so we analysed data from all participants together. Baseline weight correlated with total weight loss ( r = 0.33, P < 0.001) and was therefore used as a covariate in the analysis of weight loss over time, which uses repeated measures analysis of covariance. In the intention to treat analysis, we used ANOVA to examine differences between groups; where ANOVA indicated a significant group effect, we performed post hoc pairwise testing with Tukey's HSD (honestly significantly different) test. Before parametric testing, we assessed homogeneity of variance with Levene's statistic and tested for normal distribution; we used Welch's F statistic if variance of the dependent variable was not equal across groups. We analysed differences between participants who completed and withdrew with t tests for continuous variables (such as age) and χ ² for categorical variables (such as sex and diet group).

Results

shows the baseline demographics and anthropometric measures. The mean time spent on the diet was 24.3 (SD 1.56) weeks and did not differ between diet groups ( F = 2.0, P = 0.12).

Table 1

Weight and fat loss

Monthly weight loss by using all available data () was high initially but then slowed. Mean weight loss was significantly higher in the Atkins group than in the other diet groups during the first four weeks ( F = 6.9, df = 3, P < 0.001): Atkins 4.4 kg (SD 2.45, range 13.5 to 0.3 kg), Weight Watchers 2.86 kg (2.23, 12.9 to - 0.9 kg), Slim-Fast 2.68 kg (2.33, 9.4 to - 1.8 kg), and Rosemary Conley 3.17 kg (2.02, 8.1 to - 2.0 kg). At other time points, mean weight loss did not vary significantly between the diet groups ().

Table 2

Loss of body fat showed similar patterns (). In the first two months, the greatest loss of body fat was seen in the Atkins group; this loss was not significantly different from that seen in the Weight Watchers or Rosemary Conley groups, but it was significantly greater than that seen in the Slim-Fast group. Fat loss was significantly greater in all four diet groups than in the control group. Between two and six months, fat loss (kg and percentage) slowed down, and the diets groups did not differ significantly. Between baseline and six months fat loss did not differ between diet groups, but fat loss in all diet groups was significantly greater than in the control group. All diets resulted in a reduction in waist circumference. Waist reduction (at six months) was highly correlated with total weight loss ( r = 0.81, P < 0.001) and moderately correlated with percentage of body fat lost ( r = 0.64, P < 0.001).

Cardiac risk factors

We found few significant differences in cardiac risk factors between the diets groups and the control group (). Initially, the fall in systolic pressure in the Atkins group was significantly greater than in the Slim-Fast group but not the other groups, probably because of the relatively greater initial weight loss in the Atkins group. Regression analysis showed that total weight loss over time had the greatest influence on systolic and diastolic pressure (adjusted R ² 0.61 for change in systolic pressure and 0.79 for change in diastolic pressure).

Table 3

Glucose concentrations fell slightly over time; only in the Weight Watchers group was fasting glucose significantly lower than in the control group. In the first two months, a significant but small drop in total cholesterol was seen in all diet groups except for the Atkins group. By six months, cholesterol had fallen significantly compared with the control group only in the Weight Watchers group (by 0.55 mmol/l).

Analysis of completers

A secondary analysis of data from participants who completed the trial shows the range of weight lost by these highly motivated participants, who probably adhered most strongly to the randomly allocated diets. shows the range of total weight lost; some participants lost more than 25 kg over the six month study period, whereas others gained weight ().

After six months all diets resulted in a clinically useful mean reduction in percentage body weight: Rosemary Conley 9.9% (SD 5.6%), Weight Watchers 9.0% (5.6%), Atkins 8.9% (5.6%), and Slim-Fast 6.8% (5.3%); no significant differences were seen between the diets but all were more successful than no diet (controls gained 0.95%, 3.3%). The proportion of participants who completed the trial and lost at least 10% of their body weight at six months was 46% for the Rosemary Conley group, 45% for the Atkins group, 36% for the Weight Watchers group, and 21% for the Slim-Fast group. These losses were achieved despite the random allocation of diets.

Compliance with the diets

Reported attendance at slimming clubs was similar at two months (Rosemary Conley 79%, Weight Watchers 66%) and six months (47%, 47%). Slim-Fast recommends 14 meal replacements each week; participants reported 10 each week at two months and eight at six months. With the Atkins diet, reported portions of carbohydrate foods fell from 40 each day at baseline to five at two months and seven at six months.

Withdrawal

Eighty three (28%) participants had withdrawn by six months (); 53 (64% of the total number) had withdrawn by week 8, and at this time only seven (8%) participants who withdrew had lost more than 5% of their body weight compared with 53 (25%) who completed the trial. Older participants were significantly more likely to complete than younger ones (mean age 41.6 (9.9) v 36.8 (10.4); t = - 3.7, P < 0.001; 95% confidence interval 2.3 to 7.4). No differences in diet, centre, or sex were found between participants who completed or withdrew. Withdrawal in the control group (21; 35%) was mostly because participants did not wish to delay dieting.

Table 4

Follow-up at 12 months

At 12 months, 158 participants (54% of the original sample) returned data; 29 had originally been allocated to the Atkins diet, 33 to Weight Watchers, 33 to Slim-Fast, 35 to Rosemary Conley, and 28 to the control group. Dieting behaviour had changed considerably: only 58 (45%) were still keeping to their originally allocated diets (nine to Atkins, 20 to Weight Watchers, nine to Slim-Fast, 20 to Rosemary Conley). Twenty five (19%) had swapped dietary programmes and 47 (36%) were following their own diet or exercise plan. More participants in the unsupported programmes (Atkins diet and Slim-Fast) withdrew than in the supported programmes (χ ² = 8.34, df = 3.0, P = 0.04). Participants in the control group who had switched to dieting (mean weight loss 6.37, SD 4.5 kg) also preferred group based approaches because just over half chose Weight Watchers.

Because so many participants changed diets (25% of men and 29% of women), we also analysed weight loss in participants who had maintained the diet to which they were initially allocated (). Statistical analysis is limited by sample size but indicates that weight rebound after the initial six months was higher in the unsupported programmes; however, all diets resulted in a clinically useful weight loss of around 10% after 12 months in participants who had persisted with the diet allocated.

Table 5

Discussion

Clinically beneficial weight loss is possible through commercially available strategies, and reduced blood pressure and waist circumference accompany weight loss. The four different approaches were equally effective after six months. Reductions in weight and body fat were seen with the Atkins diet within the first eight weeks of dieting, so that the large weight changes seen with low carbohydrate diets are not caused by loss of body water alone. The Atkins diet had no detrimental effects on total cholesterol concentrations or renal function, although the overall safety of the diet was not tested.

The range of absolute weight loss in participants who completed the study was wide. Importantly, we did not try to standardise energy intake across the groups, so that the effects reflect the participants' interpretation of and compliance with the diet allocated. However, the mean absolute weight loss of around 8 kg is comparable to other studies. Compliance with each diet varied greatly. Weight can be lost only by a sustained negative balance of energy, so the degree of adherence to a diet will predict success or failure if activity levels remain constant. More information is needed to enable health professionals to decide which dietary approach may suit their patients. Currently, we cannot predict the dietary approach best suited to each person to lose weight and maintain weight loss in the longer term, but it is clear that "one size does not fit all."

Our study was used to make the BBC series on diet trials, which featured a small number of people. Since motivation to meet goal weights and patients' expectations of weight loss are key determinants of success, participants may have been influenced by the media interest. Overall, around 5% of participants were featured in the television programmes, and most participants knew that they would not be filmed within the first few weeks. Excluding data from the 15 filmed participants had no effect on the overall statistical outcomes shown in this study. The withdrawal rate was comparable to other longitudinal studies of weight loss.⁻

No dietary differences were apparent at six months, but behaviour from six to 12 months points towards an advantage of programmes based on group support. The need for a "quick fix" and the relative lack of interest that people show in achieving modest weight loss contribute to lack of adherence to most diets in the long term. People who had kept to their allocated diet lost about 10% of their weight, despite some weight rebound, but some regression to the mean effect was seen. These results provide information on the "best effect" that the most highly motivated subjects may hope to achieve over one year.

In conclusion, commercial weight loss programmes can help people with uncomplicated obesity. Our study provides data on how much weight patients can expect to lose by dieting, and these data could help practitioners in managing patients' some-times unrealistic expectations of weight loss targets. The benefits to health of modest weight loss and maintaining that loss over long periods need to be emphasised.
What is already known about this topic
The prevalence of obesity and overweight with its subsequent comorbidities is growing in the UK

Commercial diets are an increasingly popular option for weight management
What this study adds
The comparative efficacy of four commercial diets was similar

The health benefits associated with a modest loss of weight (5-10% body weight) can be gained by people following a range of dietary regimens for six months with little support from health professionals

Notes

Contributors: HT was the principal investigator and is guarantor. She contributed to the study design, data analysis, interpretation, drafting, and writing of the paper. DJM and LMM contributed to the study design, data analysis, interpretation, drafting, and writing of the paper. KRF contributed to the study design, interpretation, reporting, and critical review of paper. SB contributed to study execution, data collection, and critical review of the paper. IAM, MAT, MBEL, CML, and AdeL contributed to the study planning, interpretation, reporting, and critical review of the paper. Thanks to David Lovell for statistical advice; Manana Stanley, Rebecca Hiscutt, and Anne Herriot for planning, study execution, and data collection; Monique Raats and Richard Shepherd for study planning; Kathryn Hart, Rachel Barratt, Karen Sargent, Sarah Jones, Julie Littlewood, Sujata Dissanayake, Elizabeth Simpson, and Michelle Hazell for data collection; Mark Davis for study design and data collection; Katherine Collings for planning, study execution, and data collection; Paula J Robson, Julie MW Wallace, Maxine P Bonham, and Laura Nichol for study execution and data collection; Susan Jebb for study design; and Kirsten Rennie for sample size determination.

Competing interests: KRF receives consulting fees for serving on the scientific advisory panel of Slimming World, a company that offers a support service for weight loss. This company was not involved in this trial but as it is similar to Rosemary Conley and Weight Watchers, the conclusions may have implications for the company.

Funding: The study was sponsored by the BBC. The BBC had no role in the study design; collection, analysis, or interpretation of data; or report writing.

Ethical approval: South East multicentre research ethics committee, approval number MREC 01/01/44. Local ethics committee approval was also obtained at each centre.

References

1. Department of Health. White paper on public health. Saving lives: our healthier nation. London: Stationery Office, 1999.

2. Royal College of Physicians. Storing up problems: the medical case for a slimmer nation. London: RCP, 2004. [ PMC free article] [ PubMed]

7. Perri MG. The maintenance of treatment effects in the long term management of obesity. Clin Psychol Sci Pract 1998;5: 526-43. [ Google Scholar]

8. Atkins R. Dr Atkins' new diet revolution. South Dakota: Vermillion, 1999.

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Randomised controlled trial of four commercial weight loss programmes in the UK: initial findings from the BBC "diet trials"

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Helen Truby, senior lecturer in nutrition and dietetics, 1 Sue Baic, lecturer in nutrition, 2 Anne deLooy, professor of dietetics, 3 Kenneth R Fox, professor of exercise science, 2 M Barbara E Livingstone, professor of nutrition, 4 Catherine M Logan, PhD student, 4 Ian A Macdonald, professor, 5 Linda M Morgan, professor of nutritional endocrinology, 1 Moira A Taylor, lecturer in nutrition and dietetics, 5 and D Joe Millward, professor of human nutrition 1 Objective To compare the effectiveness of four commercial weight loss diets available to adults in the United Kingdom.

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The Atkins diet is a low-carb diet, usually recommended for weight loss.

Proponents of this diet claim that you can lose weight while eating as much protein and fat as you want, as long as you avoid foods high in carbs.

In the past 12 or so years, over 20 studies have shown that low-carb diets without the need for calorie counting are effective for weight loss and can lead to various health improvements.

The Atkins diet was originally promoted by the physician Dr. Robert C. Atkins, who wrote a best-selling book about it in 1972.

Since then, the Atkins diet has been popular all over the world with many more books having been written.

The diet was originally considered unhealthy and demonized by the mainstream health authorities, mostly due to its high saturated fat content. However, new studies suggest that saturated fat is harmless (, ).

Since then, the diet has been studied thoroughly and shown to lead to more weight loss and greater improvements in blood sugar, "good" HDL cholesterol, triglycerides and other health markers than low-fat diets (, ).

Despite being high in fat, it does not raise "bad" LDL cholesterol on average, though this does happen in a subset of individuals ().

The main reason why low-carb diets are so effective for weight loss is that a reduction in carbs and increased protein intake lead to reduced appetite, making you eat fewer calories without having to think about it (, ).

You can read more about the health benefits of low-carb diets in this article.

The Atkins diet is split into 4 different phases:

Phase 1 (induction): Under 20 grams of carbs per day for 2 weeks. Eat high-fat, high-protein, with low-carb vegetables like leafy greens. This kick-starts the weight loss.

Phase 2 (balancing): Slowly add more nuts, low-carb vegetables and small amounts of fruit back to your diet.

Phase 3 (fine-tuning): When you're very close to your goal weight, add more carbs to your diet until weight loss slows down.

Phase 4 (maintenance): Here you can eat as many healthy carbs as your body can tolerate without regaining weight.

However, these phases are a bit complicated and may not be necessary. You should be able to lose weight and keep it off as long as you stick to the meal plan below.

Some people choose to skip the induction phase altogether and include plenty of vegetables and fruit from the start. This approach can be very effective as well.

Others prefer to just stay in the induction phase indefinitely. This is also known as a very low-carb ketogenic diet (keto).

You should avoid these foods on the Atkins diet:

Sugar: Soft drinks, fruit juices, cakes, candy, ice cream, etc.

Grains: Wheat, spelt, rye, barley, rice.

Trans fats: Usually found in processed foods with the word "hydrogenated" on the ingredients list.

"Diet" and "low-fat" foods: These are usually very high in sugar.

High-carb vegetables: Carrots, turnips, etc (induction only).

High-carb fruits: Bananas, apples, oranges, pears, grapes (induction only).

Starches: Potatoes, sweet potatoes (induction only).

Legumes: Lentils, beans, chickpeas, etc. (induction only).

You should base your diet around these healthy foods.

Meats: Beef, pork, lamb, chicken, bacon and others.

Fatty fish and seafood: Salmon, trout, sardines, etc.

Eggs: The healthiest eggs are omega-3 enriched or pastured.

Low-carb vegetables: Kale, spinach, broccoli, asparagus and others.

Full-fat dairy: Butter, cheese, cream, full-fat yogurt.

Nuts and seeds: Almonds, macadamia nuts, walnuts, sunflower seeds, etc.

Healthy fats: Extra virgin olive oil, coconut oil, avocados and avocado oil.

As long as you base your meals around a fatty protein source with vegetables or nuts and some healthy fats, you will lose weight. It's that simple.

Beverages

Here are some drinks that are acceptable on the Atkins diet.

Water: As always, water should be your go-to beverage.

Coffee: Many studies show that coffee is high in antioxidants and quite healthy.

Green tea: A very healthy beverage.

Alcohol is also fine in small amounts. Stick to dry wines with no added sugars and avoid high-carb drinks like beer.

There are many delicious foods you can eat on the Atkins diet.

This includes foods like bacon, heavy cream, cheese and dark chocolate.

Many of these are generally considered fattening because of the high fat and calorie content.

However, when you're on a low-carb diet, your body increases its use of fat as an energy source and suppresses your appetite, reducing the risk of overeating and weight gain.

If you'd like to know more, check out this article on 6 Indulgent Foods That Are Low-Carb Friendly.

Despite what you may have heard, the Atkins diet is quite flexible.

It's only during the two-week induction phase that you need to minimize your intake of carb sources.

After induction is over, you can slowly add back healthier carbs such as higher-carb vegetables, fruits, berries, potatoes, legumes and healthier grains like oats and rice.

However, chances are that you will need to stay moderately low-carb for life, even if you reach your weight loss goals.

If you start eating the same old foods again in the same amounts as before, you will gain back the weight. This is true of any weight loss diet.

It is possible to do the Atkins diet as a vegetarian (and even vegan), but difficult.

You can use soy-based foods for protein and eat plenty of nuts and seeds. Olive oil and coconut oil are excellent plant-based fat sources.

Lacto-ovo-vegetarians can also eat eggs, cheese, butter, heavy cream and other high-fat dairy foods.

This is a sample menu for one week on the Atkins diet.

It's suitable for the induction phase, but you should add more higher-carb vegetables and some fruits as you move on to the other phases.

Monday

Tuesday

Breakfast: Bacon and eggs.

Lunch: Leftover chicken and veggies from the night before.

Dinner: Bunless cheeseburger, with vegetables and butter.

Wednesday

Thursday

Friday

Saturday

Sunday

Make sure to include a variety of different vegetables in your diet.

For a few examples of healthy and satisfying low-carb meals, check out this article on 7 Healthy Low-Carb Meals in Under 10 Minutes.

Healthy Low-Carb Snacks

Most people feel that their appetite goes down on the Atkins diet.

They tend to feel more than satisfied with 3 meals per day (sometimes only 2).

However, if you feel hungry between meals, here are a few quick healthy snacks:

Leftovers.

A hard-boiled egg or two.

A piece of cheese.

A piece of meat.

A handful of nuts.

Some Greek yogurt.

Berries and whipped cream.

Baby carrots (careful during induction).

Fruits (after induction).

It's actually very easy to follow the Atkins diet at most restaurants.

1. Get extra vegetables instead of bread, potatoes or rice.

2. Order a meal based on fatty meat or fatty fish.

3. Get some extra sauce, butter or olive oil with your meal.

It's a good rule to shop at the perimeter of the store. This is usually where the whole foods are found.

Eating organic is not necessary, but always go for the least processed option that fits your budget.

Meats: Beef, chicken, lamb, pork, bacon.

Fatty fish: Salmon, trout, etc.

Shrimp and shellfish.

Dairy: Greek yogurt, heavy cream, butter, cheese.

Vegetables: Spinach, kale, lettuce, tomatoes, broccoli, cauliflower, asparagus, onions, etc.

Berries: Blueberries, strawberries, etc.

Nuts: Almonds, macadamia nuts, walnuts, hazelnuts, etc.

Seeds: Sunflower seeds, pumpkin seeds, etc.

Fruits: Apples, pears, oranges.

Coconut oil.

Olives.

Extra virgin olive oil.

Dark chocolate.

Avocados.

Condiments: Sea salt, pepper, turmeric, cinnamon, garlic, parsley, etc.

It's highly recommended to clear your pantry of all unhealthy foods and ingredients. This includes ice cream, sodas, breakfast cereals, breads, juices and baking ingredients like sugar and wheat flour.

If you're serious about the Atkins diet, consider buying or borrowing one of the Atkins books and simply get started as soon as possible.

That being said, the detailed guide in this article should contain everything you need to succeed. To create a printable version, click here.

For recipe ideas, check out this article on 101 Healthy Low-Carb Recipes That Taste Incredible

At the end of the day, the Atkins diet is a healthy and effective way to lose weight. You won't be disappointed.

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The Atkins Diet: Everything You Need to Know

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We include products we think are useful for our readers. If you buy through links on this page, we may earn a small commission. Here's our process. The Atkins diet is a low-carb diet, usually recommended for weight loss.

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Cut your risk of diabetes | Atkins Low Carb Diet

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You can reduce your risk of getting diabetes significantly by making a few simple changes, like opting for a low carb diet. Read about it in our blog!

# data[].attributes.attachment_link.title
Cut your risk of diabetes | Atkins Low Carb Diet

# data[].attributes.attachment_link.description
You can reduce your risk of getting diabetes significantly by making a few simple changes, like opting for a low carb diet. Read about it in our blog!

# data[].attributes.attachment_link.title
Cut your risk of diabetes | Atkins Low Carb Diet

# data[].attributes.attachment_link.description
You can reduce your risk of getting diabetes significantly by making a few simple changes, like opting for a low carb diet. Read about it in our blog!