Grapefruit Diet. People have been doing the Grapefruit Diet for decades with the thought that grapefruit burns fat. It doesn't burn fat, but since it is a kind of elimination diet, people do lose weight. The truth is that grapefruit is rich in vitamin C and is low glycemic food. Grapefruit is not just for breakfast anymore and can be used in desserts like pink grapefruit cupcakes. Check out the recipe on Cupcakes.