As we age, we lose approximately 5 pounds of muscle mass per decade (Frontera et al., 2000). Because our muscles are metabolically active 24 hours a day, our muscle mass contributes significantly to our resting metabolic rate, which accounts for 70% of the calories we burn per day (Wolfe, 2006). Therefore, as we lose muscle mass, our metabolic rate slows, which then causes us to gain weight, resulting in approximately 15 pounds of body fat per decade (Wolfe, 2006). Fortuna