Also known as the 5:2 diet, “The FastDiet” is not a reference to how quickly the weight falls off, but to the type of eating plan you follow: intermittent fasting. Two days per week, women “fast” by eating no more than 500 calories a day, while men get 600 calories per day. Although this may seem rather unpleasant, the tradeoff is that you get to eat whatever you want on those other five days. No calorie-counting and no off-limit foods.

The Health Claims :
 

The first half of “The FastDiet” details the emerging research (done mostly on rodents) on intermittent fasting. Among its purported benefits, fasting lowers insulin, switches the body from fat storing to fat burning mode, improves cholesterol, boosts mood and cognitive function, slows down aging and decreases the risk of cancer and other diseases.