If so, you’re a lean, mean, fat burning machine. Researchers from Denmark found runners who logged about 3 miles a week lost an average of 4 pounds in a year – while keeping their diet exactly the same. BUT, runners who also cut back the usual suspects – soda, snacks and junk food – lost 12 pounds on average. And notice I said “cut back” – they didn’t have to drop those fun foods entirely. So lace up your running shoes, do 3.1 miles a week, and you’re guaranteed to lose weight.