hCG (human chorionic gonadotropin) acts like LH, the natural hormone that tells the testes to make testosterone and support sperm production. In men it is used for low testosterone caused by a pituitary or hypothalamus problem, to protect fertility and testicular size during testosterone therapy, and to help natural production restart after it has been suppressed. It does not help weight loss. It needs blood tests before and during treatment, so it should only be used under a physician.