The Grapefruit Diet, also known as the Hollywood Diet, dates back to 1930 Hollywood. This diet is based on the premise that grapefruit has fat-burning properties. There are many versions of the Grapefruit diet, but the principal is always to eat half a grapefruit before every meal and to limit calorie intake to 800 per day. The diet lasts for 12 days and, if followed correctly, you can lose up to 10 lbs. While there is no hard evidence that grapefruit burns fat, some who have completed the diet offer anecdotal success stories.