Why does weight loss slow down or stop when I am on a weight-loss diet?

Most people on weight-loss diets find that weight loss slows down and becomes increasingly more difficult. This plateau typically occurs after 1 to 2 months of dieting, and there are several reasons why this occurs. First, weight loss itself reduces energy requirements. That is, with a lower body weight, the body requires less energy. Second, rapid weight loss can cause a loss of muscle or lean tissue. Lean tissue is metabolically active, and a loss of lean tissue reduces energy requirements. Last, diets that are low in calories and/or carbohydrates deplete glycogen stores. Because glycogen has a great deal of water associated with it, people tend to experience rapid weight loss the first few weeks of dieting. For all these reasons, the rate of weight loss slows the longer a person diets.