Lawrence Frank, a professor of urban planning at the University of British Columbia, thinks so. Science News Online has the story:
In the first of the 2003 reports, researchers analyzed data from a nationwide survey in which each of some 200,000 people reported his or her residential address, physical activity, body mass, height, and other health variables. Residents of sprawling cities and counties tended to weigh more, walk less, and have higher blood pressure than did people living in compact communities, concluded urban planner Reid Ewing and his colleagues at the University of Maryland at College Park's National Center for Smart Growth Research and Education.
In the second study, health psychologist James Sallis of San Diego State University and his colleagues reported that residents of "high-walkability" neighborhoods, which have closely packed residences and a mix of housing and businesses, tended to walk more and were less likely to be obese than residents of low-walkability neighborhoods.
The photo above, taken by Oscar Ruiz, are real houses in Ixtapaluca, Mexico: http://www.neatorama.com/2006/02/19/oscar-ruiz-aerial-photos-of-mexico-city/