Weight Control
As far as metabolism goes, muscle mass is the "engine" of the calorie-burning machine. As you strength train and increase your muscle mass, you build a bigger, more efficient engine that burns more calories and helps you lose weight. The more toned your muscles, the easier it is to maintain your weight. In fact, the higher your muscle mass, the more calories you'll burn when you rest. For every pound of muscle you gain, your body uses about 50 extra calories a day.