Is it safe to go on a fad diet for a short time?

Is it safe to go on a fad diet for a short time?

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...

When you go on a fad diet, you gain the weight back again, and go on another one, so you start doing this yo-yo dieting. What happens is, your metabolism is slowing down, you're starting to store more of your calories as fat and you have less muscle. So over time, you are going to have more fat, less muscle and a slower metabolism. So after a fad diet, horrible things don't happen right away, but over time we can find that such detrimental effects occur.