Black women who live in more crowded urban cities pack on fewer pounds than their counterparts in sprawling suburban areas, according to a study published in the American Journal of Preventive Medicine.

For the study, researchers from Boston University School of Medicine’s Slone Epidemiology Center reviewed data collected in the Black Women’s Health Study, an ongoing health evaluation of 59,000 black women, started in 1995.

To get a detailed look at how obesity among urban city dwellers compared with obesity among suburban residents, researchers evaluated 18,000 New York, Chicago, and Los Angeles women. (Researchers assigned women’s residential neighborhoods an “urbanicity score” based on their neighborhoods’ density—the more crowded the neighborhood, the higher the score.)

The results? Scientists found that African-American women living in crowded cities experienced less weight gain and obesity during a six-year period compared with those who resided in more sparsely populated suburban and rural areas.

The reason? Researchers suggested the difference could be traced to one thing: physical activity. Women living in cities tended to walk more often over longer distances during their day-to-day activities. Women living in sprawling areas were more likely to use a car to get around.

What these findings mean is that policies that encourage more dense and urban residential development may play a positive role in addressing the obesity epidemic, said Patricia Coogan, MPH, a senior epidemiologist at the Slone Center, and lead study author.

And what’s in it for you? Well, if you’re a city dweller and usually walk a lot, keep stepping. And if you’ve been hopping in the car to run every errand, you may want to include long walks around the neighborhood after dinner or on the weekends to boost your activity levels.

What are some other benefits of walking? Click here to learn more.