If you are looking to drop pounds fast, a diet called the "fast diet" has become one of the top diet plans in Britain.

The secret behind the diet is fasting for just two days a week and eating as you normally would the rest of the week.

On the two fasting days, adults consume 25-percent of normal calorie intake, about 500 calories for women and 600 for men.

"When they're deprived of food their brains starts producing a protein called brain derived neuro traffic factor," said a cheif. "And what this does is, it makes you feel happier and what it also appears to do is make you smarter."

Researchers are still looking into other ways severe calorie restriction affects the brain and the rest of the body.