A five-day fast—where calorie intake is reduced to just 750 to 1,100 calories a day—every three months seems to be the optimum approach. As well as reducing the risk for most diseases, it also helps weight loss and even trims an inch or two off the waistline.
The benefits of fasting have been tested on a group of 100 healthy volunteers aged from 20 to 70. Half carried on eating normally for three months, and the rest were put on a fast for five days each month, where they ate between 750 and 1,100 calories a day with a special programme from L-Nutra, a nutrition company. After the three months, those who had been eating normally were also put on the fasting diet.
When they went on the fasting diet, all the participants lost an average of six pounds (2.7 kg), their waistlines shrank between one and two inches, their blood pressure levels fell, and inflammatory markers known as IGF-1 dropped to a range associated with a lower cancer risk.
These markers were maintained even when the participants returned to their normal lives and diets, said lead researcher Valter Longo from the University of Southern California.