Sallis started out trying to understand how to motivate people to become more physically active. But, like many of his colleagues, he soon found that whatever worked only worked a little, on a few people, for a short time. Soon, Dr. Sallis came to see the modern urban environment as a big part of the problem. Place matters, he decided, and he set about investigating the design of public spaces and their influence on physical activity and the obesity epidemic.

A professor at the University of California San Diego’s Department of Family and Preventive Medicine, Dr. Sallis also runs a foundation that has doled out about $28-million over the past decade to help foster a better understanding of how physical environment affects health with hard data that can guide urban planners and policy makers.

This week, Dr. Sallis also becomes the latest winner of the Bloomberg Manulife Prize for the Promotion of Active Health, a $50,000 award administered by McGill University. On his way to receiving the prize Dr. Sallis stopped by Toronto’s Metro Hall to share his ideas and findings with city officials and to talk about the significance of place with The Globe and Mail.

How does the design of a city affect how healthy its population is?

Throughout our whole history, people have walked for transportation. We’ve deleted that. We’ve designed that feature out of the world for many, many people and we now have the evidence that our planning and community design decisions and our transportation decisions are reducing activity and contributing to chronic diseases.

What does the research show?

You can’t do randomized controlled studies with this sort of thing, but we do have natural experiments – cities that are designed well for pedestrians and cities that are not. And when we do comparison studies that adjust for socioeconomic status and other factors we find, over and over again, that people are much more active in walkable cities. Many of those studies show that people in more walkable cities are less likely to be obese. We’ve done studies that show this across all age groups. We’ve done a study in 11 countries showing the same thing internationally. So the evidence is really adding up.

Are some cities better at others at being walkable?

Every older city is walkable, period. If they were built before cars they had to be. So we know how to make walkable cities that are fantastic and beautiful.

How does this translate into healthier behaviour?

The brain is not our friend when it comes to physical activity. We are kind of programmed for slothfulness. As we age, some of the neurons that connect movement centres and reward centres die off so we lose our ability to get pleasure from activity. That’s why we need spaces that invite people to be active. We need to feed the pleasure centres of the brain through our designs.

What should cities be doing differently?

First, start building mixed-use places again. Don’t build residential areas that are separate from commercial areas, build communities so that the places where people want to go are in walking distance. Mixed use is the key. And in transportation we’ve got to prioritize pedestrians, bicyclists and public transit, because people who use those for active transportation are healthier.

Isn’t it more costly to build this way?

The way we’re building cities now has huge consequence for health, for health care, and thus for our economies. It may be more costly to build more walkable areas, more sidewalks and plant more trees, but there are economic benefits too. Property values tend to be higher and infrastructure costs tend to be lower when there is less sprawl.

Is this something only big cities can afford to care about?

A lot of small cities are making these changes too. They’re putting in bike lanes and redeveloping their downtowns to be more walkable, not for health reasons but for economic development. For example the town of Redding in northern California, which is divided by the Sacramento River, decided it needed a landmark. And so they put in a pedestrian bridge that was the anchor for their economic development. People like walkable places, sidewalk cafés and so on. And these places are economically attractive because people associate them with being dynamic and creative.

Doesn’t climate affect how active a city can be?

Only to a degree. My favourite example is Minneapolis. This is one of those cities that decided, regardless of how unfavourable the weather may sometimes be, that it was going to promote and facilitate bicycling. As a result, their bicycling increased from 1 per cent of trips to 4 per cent of trips. It may not seem like much but that’s a higher percentage than San Diego. It’s not the climate; it’s the planning and it’s the policy.

What do you notice that strikes you about Toronto? | I’ve seen bicyclists but no protection for bicyclists.

Where does research in this area need to go next? | We need to see more studies that follow people over time. We need to see, if something changes, do people change.