Metabolism is the process through which your body breaks down carbohydrates, fats and proteins to produce the energy needed for the body to maintain itself. Your metabolic rate depends on the number of calories you consume versus the amount of calories you burn when engaging in various activities such as eating, exercising and resting. If your metabolism has slowed down, you can take steps to get it back on track.

1 Increase your body's need for energy. The body burns fat only when it needs energy. Engage in aerobic exercise, interval training and weight training. All of these activities force your body to use its energy reserve.
2 Don't set your air conditioner or heating unit for maximum comfort. When your body feels too comfortable, it reduces the amount of energy your body expends to stay warm or cool. Set the thermostat so that you feel a little too hot or a little too cool. This will help you consume less food.
3 Eat every two to three hours. The more often you eat the more you stimulate your metabolism. The body becomes more comfortable using up energy because it knows you won't allow it to starve. This is one reason eating breakfast is important. Skipping meals encourages your body to store fat just in case you don't eat for a while.
4 Eat a well-balanced meal. Your small, frequent meals should consist of protein, vegetables and fiber. Vegetables are low in fat but high in nutrients. Your body requires extra energy for metabolizing and digesting protein and fiber. You burn twice as many calories digesting protein than other types of food such as fats or carbohydrates.
5 Get enough sleep. Lack of sleep slows down your metabolism because the amount of calories you burn at rest decreases.
6 Keep moving. Stand up as opposed to sitting down when possible. Walk whenever you can. Frequently interrupt stationary activities like working at your desk or watching TV with active breaks.