Controlling metabolism is one of the best ways to control weight. The key measurement is the basal metabolic rate (BMR) (the amount of calories the body requires at rest). The BMR consumption varies most with the pounds of muscle the body has.
Muscle loss begins after age 25 and averages about 0.5% annually without extra efforts. For every 10 pounds of muscle lost 600 less calories are needed but our appetites do not correspondingly decrease.