As you age, your basal metabolic rate slows down, and those large amounts of food you easily could put away while staying trim when you were twenty seem to go to the hips and abdomen now that you are approaching thirty something. The basal metabolic rate is the body’s engine, explains Kathleen Zelman, Dietetic Internship Director, Alton Ochsner Medical Foundation, New Orleans. “The rate gradually slows down with time and the engine becomes less efficient as part of the natural aging process. During this time, portions of muscle tissue turn to fat, which is less metabolically active than muscle, No one is immune from those metabolic changes that come with aging.”