Side Effects of Rapid Weight Loss

A pound of body fat is composed of 3,500 calories, which need to be either burned or eliminated from the diet in order for a person to lose weight. The average person can only lose 1 to 2 pounds of body weight a week. Diets promising rapid weight loss promise much bigger numbers, which are sometimes possible but not without serious side effects.

Loss of Muscle

Rapid weight loss usually goes hand in hand with muscle loss. When the body does not get enough nutrients from the diet (common in very low calorie or liquid diets, which are used for rapid weight loss), it resorts to eating away at the muscles for energy. Fat is not a very effective source of energy and the body considers fat as energy reserve, thus only using it as a last resource. Loss of muscle leads to a sluggish metabolism, which in turn will make it easier to regain weight once the person goes back to eating normally. It also causes an untoned appearance or what is referred to as being "skinny fat."

Loose Skin

Rapid weight loss will always cause hanging skin. This is because even though skin is elastic, the stretching and shrinking process is slow. With rapid weight loss, the skin does not have enough time to adapt to the changing body and ends up loose and saggy. This is especially noticeable in the abdomen and arms. Obese people who lose large amounts of weight may eventually need cosmetic surgery to correct the problem.

Dehydration

Muscle is composed greatly of water, so with lost muscle comes a loss in the body's reserve of water. People who are losing large amounts of weight usually restrain their water intake as well to prevent bloating. Dehydration can lead to a number of problems, including dizziness, lack of energy, kidney stones, diarrhea and vomiting.

Gallstones

Sudden weight loss, as well as long periods of fasting, can disrupt the balance of cholesterol and bile salts in the gallbladder, leading to the formation of gallstones. Aside from bloating, nausea and vomiting, gallstones can also cause severe pain in the upper abdomen, between the shoulder blades and in the lower back. Surgery may be necessary to remove large stones.

Hair Loss

Hair loss is common in diet programs that cause rapid weight loss for long periods of time, such as the case of obesity surgery, liquid diets or very-low calorie diets (under 800 calories per day). Hair needs protein to grow and maintain its health. In diets that cause rapid weight loss, protein is usually reduced to a small percentage of the daily diet, as dieters usually need to concentrate in either liquids or produce to lose weight. The lack of protein in the diet will lead to brittle hair and eventually hair loss, as the body will use whatever little protein is consumed for other, more vital organ functions.