HCG diet is dangerous. You should really do your research before promoting something like that. HCG can cause testicular cancer in men and ovarian cancer in women.
At 15 years old you shouldn't be doing any kind of crazy diet. You should eat healthy and EXERCISE. You are going through puberty and should NOT mess around with dieting (other than eating healthy and exercising) as you can do far more damage than good. Exercise is key. Play sports, run around, walk around town, ride your bike, jump rope.. whatever. Just exercise a lot and make healthy food choices.