When a person suddenly stops taking in the amount of calories to which they are accustomed their body responds by slowing their metabolism. The body will act as if it is starving, which sometimes it is. Metabolism is the rate at which a person's body burns the calories needed to function normally. It is for this reason that rapid weight loss programs don't work in the long run. The body responds to the plunge in calorie intake by slowing the metabolism so that it can continue to operate on fewer calories. The dieter will hit a plateau in weight loss, which for some people stimulates a frustrating pattern of weight loss and gain, known as yo-yo dieting. Repeated attempts at rapid weight loss can permanently slow a person's metabolism, making weight loss harder with each diet. Generally, diet plans that are well balanced and do not fall below 1200 calories a day are manageable.
The Slowing of One's Metabolism
Several other things will slow a person's metabolism. The first is a lack of exercise. Exercise increases your metabolic rate both during and up to 48 hours after exercising. Muscle tissue is far more active than fat tissue and even when a person's muscles are at rest, they are actively consuming energy. A person's metabolism speeds up in order to provide muscle tissue with this energy. For this reason, we also need to make sure we provide our body with enough calories to fuel the consumption of energy. Changing the amount of muscle vs. fat in the body is the primary way in which a person can alter their metabolic rate. Our metabolism also slows as we age. The body needs fewer calories and more exercise to maintain a healthy weight. It has been found though that older women who exercise in combination with a balanced diet low in fat can counteract any decrease in their metabolic rate associated with aging.