Basically, weight management comes down to this: the more active you are, the more calories you burn. That means how much physical activity you get in a day has more impact on your weight loss and gain than a fast or slow metabolism. When you're trying to lose or maintain weight, physical activity is one of the most important factors because it's under your control -- you choose how sedentary or active you want to be.
A 150-pound person who runs for 60 minutes (with a pace of a 10-minute mile) will burn about 680 calories, or roughly the number of calories in a Whopper from Burger King. But even the most sedentary among us is still burning calories, just not very many. Our bodies use about 10 percent of the calories from the foods we eat to process that food. Just don't count on that 10 percent to impact your waistline.