The On and Off Diet is a fad diet (Also sometimes referred to as the 5:2, 55 or 2:2 Diet). This type of diet suggests various calorie restrictions for a period (two weeks) followed by a period of normal diet (two weeks)
There are three easy steps to get started on the On & Off Diet
- Calculate your normal calorie requirements and Deduct (minus) 20 percent from that number
- Calculate new portion sizes based on your own calorie restricted total
- Start on your calorie restricted diet for two weeks (On) and then for two weeks normal diet (Off) – Rinse and repeat.
The alleged benefits of an intermittent diet is that your metabolism, apparently, will not slow down as easily as with a constant diet or lifestyle. Claims made by proponents include the psychological benefits of knowing that periods of scarcity will be followed by periods of plenty.
What Sandra says about the On & Off Diet: There are some scientific evidence that infrequent fasting has health benefits, but further studies are required.
About Fad Diets
Fad diets are exactly that, a Fad. The New York Times wrote that after the TV program “The Biggest Loser” bodies fought back against weight loss and that contestants metabolisms became even slower than before within a few years. 
Results of a new study, in the journal of obesity, found that : “Metabolic adaptation persists over time and is likely a proportional, but incomplete, response to contemporaneous efforts to reduce body weight.”
This requires a full article by itself, but basically means that if you were a certain weight your body will fight back, over many years, to regain that weight.
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