From a University of Toronto working paper:
We study the relationship between urban sprawl and obesity. Using data that tracks individuals over time, we find no evidence that urban sprawl causes obesity. We show that previous findings of a positive relationship most likely reflect a failure to properly control for the fact the individuals who are more likely to be obese choose to live in more sprawling neighborhoods. Our results indicate that current interest in changing the built environment to counter the rise in obesity is misguided.
More here; study here; via Peter Gordon. Related: Same story from Oregon State University study Related: Evidence for built environment-physical activity relationship “currently sparse”