Grapefruit contains ample vitamin C to facilitate adequate function of your metabolic system. Research has demonstrated that vitamin C has some fat-burning capabilities, and half a grapefruit contains approximately 40 mg of vitamin C.
Studies have also noted that chemicals in grapefruit may reduce levels of insulin, helping to regulate fat metabolism. When insulin is steady, the body processes energy more efficiently.
In a 12-week study conducted at The Scripps Research Institute (La Jolla, Calif.), researchers discovered that subjects who consumed a half grapefruit before each meal, three times per day, lost an average of 3.5 pounds, while subjects who consumed the same meals without grapefruit lost only 0.5 pounds.