In its December 2007 issue, Scientific American Body published one of the best articles I’ve read on the topic of the relationship between the “built environment” - our roads, buildings, etc. - and our health. The article, by Kathryn Brown, presents some of the relevant statistics; describes efforts by “built-environment advocates” in communities such as Atlanta, Georgia, and Columbia, Missouri; and examines the scientific debate on how best to build communities that foster physical activity.

I was especially interested in the paragraphs below (emphasis added), which describe research that shows the positive influence of densely populated, mixed-use communities on physical activity. (Mixed-use communities mix different land uses together - residential, commercial, recreational, public, etc. - to give people shorter distances between different destinations.) Just to show that I’m interested in an open inquiry, I’ve included the author’s brief discussion of a Heritage Foundation editorial that questions the role of the built environment in determining a condition such as obesity.

“There’s almost a desperation around the country to do something about childhood obesity,” says [Robert Wood Johnson Foundation] Active Living Research program director James Sallis, who is also a psychologist at San Diego State University. Active Living Research, in particular, is working to assemble evidence that the right built environments boost physical activity and improve health. “Increasingly, we plan to focus on funding peer-reviewed research that documents the most promising ways to reduce childhood obesity,” Sallis says.

In one of his own studies, published this past March in the American Journal of Health Promotion, Sallis collaborated with urban design specialist Lawrence Frank of the University of British Columbia and others to link Atlanta’s built environment with walking patterns in the city. Surveying more than 3,000 children and their parents, the researchers found that kids aged 12 to 15 were three times more likely to walk half a mile a day if a park, store or other popular destination were located within about 0.62 mile (one kilometer) of their homes. Overall, the team reported, children and families living in a “mixed-use” community—which offers destinations within walking distance—walk significantly more.

Walking half a mile may not sound like much exercise, but Pate puts it into perspective. He notes that preventing excess weight gain is likely to be easier than losing pounds. Furthermore, he says, most people pack on pounds gradually, because their day-to-day consumption of unburned calories is relatively small. Over time, for instance, 50 extra calories a day can cause someone to become overweight. And “a 10-year-old can burn more than 50 calories just walking to or from school or the park on a daily basis,” Pate points out.

Still, skeptics question how much sprawl is to blame for obesity. In a 2003 online editorial, the Heritage Foundation, a conservative think tank in Washington, D.C., argued that without more evidence, public policy should not require denser, mixed-use community designs. The foundation emphasized that data from the CDC on 445 counties showed few overall weight differences between communities designed differently. “For the country as a whole and comparing citizen weight in the 25 counties at either extreme of sprawl and compactness, 19.2 percent of residents in the least sprawling communities were obese, while 21.2 percent in the most sprawling were obese,” the editorial noted, calling such differences “trivial.”

Sallis has heard that argument before. “Most people would agree that there is not going to be a single solution to childhood obesity,” he responds. “We have to pursue many solutions. We have to make it harder to drive and easier to bike. We have to make it easier to find affordable, healthy food and harder to find junk food. We have to make it easier for kids to be active at school and after school. Obesity is a difficult problem to fix, but it’s certainly possible—and environment is a factor.”

In particular, Sallis continues, minority and low-income communities need new solutions. Studies have shown that these neighborhoods, on average, include fewer parks, more fast food outlets and more crime than affluent or Caucasian neighborhoods. Against this backdrop, these communities frequently suffer higher rates of obesity. Active Living Research plans to increase its support for reviews of these high-risk populations, Sallis says.

I was also glad to see that the article begins by describing the active-transportation lifestyle of a researcher who lives in Davis, California.

This entry was posted on Monday, February 11th, 2008 at 12:59 pm and is filed under Biking/Walking, Health, Science, Urban Design.