Rates of obesity, diabetes lower in neighborhoods that are more walkable

The global increase in obesity is a major health problem. One approach to reduce obesity through diet and exercise that is gaining interest among public health professionals and urban planners is to redesign the built environment to offer more opportunities for physical activity and healthy eating. Neighborhoods that favor pedestrian activities -- those with high population density, high numbers of destinations within walking distance of residential areas, and well-connected streets -- are characterized by higher rates of walking and bicycling for transportation and lower rates of car use.

Gillian L. Booth, M.D., of the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, and colleagues examined whether urban neighborhoods that are more walkable are associated with a slower increase in overweight, obesity, and diabetes than less walkable neighborhoods. The researchers used annual provincial health care (n = 3 million per year) and biennial Canadian Community Health Survey (n = 5,500 per cycle) data for adults (30-64 years) living in Southern Ontario cities. Neighborhood walkability was derived from a validated index, which included 4 equally weighted components: population density, residential density, walkable destinations (number of retail stores, services [e.g., libraries, banks, community centers], and schools within a 10-minute walk), and street connectivity. Neighborhoods were ranked and classified into quintiles from lowest (quintile 1) to highest (quintile 5) walkability.

There were 8,777 neighborhoods included in the study. In 2001, the adjusted prevalence of overweight and obesity was lower in quintile 5 vs quintile 1 (43 percent vs 54 percent). Between 2001 and 2012, the prevalence increased in less walkable neighborhoods, while the prevalence did not significantly change in areas of higher walkability. In 2001, the adjusted diabetes incidence was lower in quintile 5 than other quintiles and declined by 2012. In contrast, diabetes incidence did not change significantly in less walkable areas.

Rates of walking or cycling and public transit use were significantly higher, and that of car use lower in quintile 5 vs quintile 1 at each time point, although daily walking and cycling frequencies increased only modestly from 2001 to 2011 in highly walkable areas. Leisure-time physical activity, diet, and smoking patterns did not vary by walkability and were relatively stable over time.

The authors note that the "ecologic nature of these findings and the lack of evidence that more walkable urban neighborhood design was associated with increased physical activity suggest that further research is necessary to assess whether the observed associations are causal."

Editorial: Can Walkable Urban Design Play a Role in Reducing the Incidence of Obesity-Related Conditions?

Andrew G. Rundle, Dr.P.H., of Columbia University, New York, and Steven B. Heymsfield, M.D., of the Pennington Biomedical Research Center, LSU System, Baton Rouge, comment on the findings of this study in an accompanying editorial.

"The findings of the study by Creatore et al reported in this issue of JAMA provide further large-scale and longitudinal support for the hypothesis that urban design choices promoting pedestrian activity are associated with greater engagement in active transport (walking and cycling), lower prevalence of overweight/obesity, and lower diabetes incidence at the population level. This study will make a prominent contribution to the research base that informs the urban design and health policy debates for years to come."