Running is a great way to burn fat for fuel, but actually losing weight involves total caloric intake and expenditure. Running at a low intensity for a long period of time primarily targets fat as a fuel source, while running at a high intensity for a shorter duration primarily uses carbohydrates as the main source of energy.
Running is an excellent form of exercise to help lose weight. To successfully lose pounds, one must expend more calories than taken in. While high intensity running, with a heart rate at 80 to 90 percent of the maximum heart rate, burns a lot of calories in a short period of time, people should alternate the intensity of workouts to help avoid injury and getting bored with the same regimen.