Some people are so desperate to lose fat and weight that they go for crash diets. Initially they may help you to lose fat and weight and sometimes they may help you to lose several pounds. However, it is not very good for your metabolism and such crash dieting can kill your metabolism.

Fat loss is temporary

When you use a crash diet do lose fat, initially you may lose some but it is very temporary. Such diets do strange things to your body's water weight. Your body generally holds 4 g of water for every 1 g of carbohydrate consumed. So, depending on the body mass and your diet it is possible for you to carry 20 pounds or more water in your system. Crash diets limit food and no energy for holding the water and as a result of that your body starts to lose water weight. So, people generally lose several pounds of weight in the first week of a crash diet. The loss of water from your body will damage your body by reducing the levels of hydration. Also when you reintroduce the carbohydrates in your diet and increase the number of calories, the bodyweight will again go up. Proper hydration is very important for new cell generation and communication. You may lose cognitive ability and may also suffer from other injuries if you suffer dehydration.

Slows down your metabolism

A crash diet will slow down your metabolism. In such a diet, you cut calories drastically to create a big calorie deficit so that you can lose fat quickly. When you reduce calories, you are cutting down energy forces and in that case your body will simply go into survival mode and that will slow down your metabolism. If you deprive your body of adequate nutrition, your metabolism will slow down and it will start to use fat and muscle for fuel. Even though you will lose some fat, you will also lose muscle from your body. When you lose muscle, your metabolism will slow further down so that your body can preserve whatever is left.

As you continue the crash diet for some time, energy levels will diminish quickly and you will be tired. Your body will gradually start to shut done vital metabolic and biological processes so that it can save energy.

Reduced immune function

When you go for a crash diet, you consume less calories than you require and that will weaken your immune system. It means your body will not be able to resist diseases more and it will expose your body to different types of diseases and health problems. Such diets do not have the balanced ratio of proteins, fats and carbohydrates which are very much necessary for keeping your immune system at the optimum level.

Hormonal imbalances

If you follow a crash diet, because of the calorie deficit, it will result in hormonal imbalances. It will create an imbalance of ghrelin and leptin, which at the hormones responsible for managing your hunger. As a result of that you may have very strong food cravings which will force you to binge eat things that you generally don't eat.

Crash dieting is like destroying your metabolism and your body for the sake of losing a few pounds.

References

1. Xtreme Fat Loss Diet
2. NIH study finds cutting dietary fat reduces body fat more than cutting carbs
3. Healthy weight loss