A calorie is a unit of energy. Metabolism – the amount of energy your body uses at rest in a day – is measured in calories.

By nature, the muscles in your body require a lot of energy (metabolism) to keep going. So when you increase your muscle mass, you usually increase your metabolism.

If you eat or drink more calories than your body needs for energy, the excess is stored as fat. But if you take in fewer calories than your body needs, your body consumes muscle to make up the deficit. Therefore, dieting without exercising to maintain muscle mass can actually slow your metabolism, which adjusts downward because there’s not as much muscle requiring energy.

You naturally lose muscle mass as you age. Strength-building exercise can help you slow muscle loss and maintain your metabolism, and with wise food choices it can help you maintain a healthy weight.