Diet is the biggest part of it, no question, but calories are misleading. The number of calories you burn by running for an hour doesn't take into consideration

Diet is the biggest part of it, no question, but calories are misleading. The number of calories you burn by running for an hour doesn't take into consideration the increase in metabolism that will follow for up to 48 hours or the calories that will be burned in the future by the extra muscle you build even while at rest.