Fads, by definition, are short-lived, and fad diets definitely come and go, many in the blink of an eye. Here are 7 fad diets that you may never have heard of.

Grapefruit Diet
Instead of eating balanced meals, just eat grapefruit. What could go wrong?

Cabbage Soup Diet
This diet replaces most meals with cabbage soup, and also has the side effect of stinking up your entire house.

Israeli Army Diet
This diet actually has nothing to do with the Israeli Army. On this eight-day diet, only apples are eaten on the first two days, cheese for the next two, chicken for the next two, and salad for the final two.

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Breatharian Diet
Based on a belief that food isnt necessary to sustain life, someone whos on the Breatharian diet eats nothing at all.

Cookie Diet
Instead of eating a meal, those on the Cookie Diet eat low-fat cookies to quell their hunger.

Feingold Diet               
This diet adheres to the belief that artificial additives and sweeteners are responsible for hyperactivity in children, so it eliminates them. Its been widely debunked.

Negative Calorie Diet
Adherents to this diet believe that certain foods have negative calories, meaning that it burns more calories to digest them than the food provides. These foods include celery, broccoli, and cabbage. While no food is actually negative-calorie, some people lose weight on it because it fills the stomach with foods that arent calorically dense. 

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