Why do I lose weight quickly on a fad diet?

Why do I lose weight quickly on a fad diet?

Andrea Giancoli (Registered Dietician ) gives expert video advice on: Why do I lose weight quickly on a fad diet?; Why do I gain weight back so fast after a fad diet?; How can I lose fat instead of water weight? and more...

Usually you lose weight very quickly on a fad diet, because its very restrictive in calories, from the very beginning and that causes you to lose a lot of water weight, because you're using your stored carbohydrate that's in your body that provides energy to the brain and that stored carbohydrate is called glycogen and glycogen is mainly water. So, once you deplete your body of that glycogen, you lose a lot of that water you also start to lose lean muscle tissue because your body in not getting enough calories from outside it kind of starts to eat itself so that weight loss in the very beginning is water weight loss an lean muscle tissue, not fat loss.