Obesity is a complicated disease. It can be caused by your mom's pregnancy diet, genetics, your KFC Double Down habit, or some combination of all three. But why has the problem reached such epidemic proportions in the U.S.? Researchers at the University of Illinois think our car culture may be to blame.

After analyzing national statistics from between 1985 and 2007, the researchers found that vehicle use (measured in annual vehicle miles traveled) correlated approximately 99% with annual obesity rates. The more we sit around doing nothing in our cars, the fatter we get.

Of course, cars and roads aren't going anywhere, but we could stand to drive just a little bit less. If every licensed driver in the country cut down on travel by just one mile each day, in six years the obesity rate would drop 2.16%—cutting down on the number of obese adults by almost 5 million people, according to PhysOrg.

This may be an impossible goal; tearing Americans away from their cars is almost as difficult as detaching them from their cell phones. There will be a lot of kicking and screaming involved. But initiatives like Bike to Work Day make a difference, as do increased public transportation routes and better telecommuting work policies. And there's an added bonus to cutting down on driving: Fewer car miles means less gasoline is used in the U.S. overall, which means staving off our energy crisis just a little bit longer.

Republished with permission from FastCompany.com. Authored by Ariel Schwartz. Photo via Shutterstock.