IMO, the HCG diet is just a fad diet. The program consists of taking a shot of HCG and eating a 500cal a day diet. It's the 500 cals a day that causes the fat loss! They promote HCG as an appetite supressent, claiming that the HCG will keep you from being hungry. Interestingly, HCG will raise test in men, but in women, it will raise estrogen. Estrogen is an enemy of fat loss, so it would really be counter productive for females to use HCG while trying to lose fat