Because one pound of fat is generally equivalent to 3,500 stored calories, you need to cut or burn at least 500 calories a day to lose one to two pounds a week. In general, experts agree the best way to do this is through a combination of diet and exercise. You also need to vary your workout and routine, because as your body adapts (and improves), the same workout will burn fewer calories. Note, it can take just as long to lose the weight as it did to put it on. For example, it can reasonably take up to two months to safely lose 10 pounds.