HCG is a hormone called Human Chorionic Gonadotropin (hCG) that affects the body in several different ways, depending on the dosage. When an hCG shot is given to a woman, it stimulates the ovaries to produce and release eggs. When given to a man, it maintains the development of testosterone. There is some theory that it can also affect the hypothalamus gland, causing dramatic loss of fat tissue rather than lean muscle mass.
The most common use of the hCG shot is to stimulate ovulation in women who ovulate infrequently or not at all. The hormone also stimulates the ovaries to release an egg. An hCG shot will cause ovulation to occur within 36 to 48 hours.
A more controversial use of the hCG shot is as a way to lose weight, in conjunction with a low-calorie diet developed by British doctor A.T.W. Simeons. Simeons looked at studies of Indian women and overweight boys who were given hCG shots for fertility reasons and to stimulate puberty respectively. He noticed that both the women and boys lost fat. The FDA has stated that the use of the hCG hornome as a weight loss tool is both ineffective and dangerous.
In males, the hCG shot is used to stimulate or enhance the production of testosterone. The shot is sometimes given to boys who have problems with their pituitary glands, causing late puberty, or to men who have a low sperm count. In small boys, the hormone is sometimes used to help the testicles descend into the scrotum, if they have not done so naturally.