A Reason for the City.

According to The American Journal of Preventive Medicine, research has shown that those who live in older neighborhoods are far more likely to be thin. Older neighborhoods (mainly those of cities) were originally designed with walking and biking in mind, not driving (unlike the suburbs, which were designed for cars).

For every decade added to their neighborhood's age, women's risk of obesity decreased 8 percent and men's obesity risk fell 13 percent. Researchers found that people with old homes are slimmer because old neighborhoods are more walkable. "The data show that how and where we live can greatly affect our health," said Ken Smith, a professor of family and consumer studies at the University of Utah. His study examined height and weight data from driver's licenses of 453,927 residents in Utah and compared them with census data on median housing age.

This shouldn't be surprising, since many suburbs aren't even designed with sidewalks.