Human chorionic gonadotropin, or HCG, is a naturally occurring glycoprotein hormone used therapeutically in medicine. HCG has gained public attention due to its controversial use in an unapproved weight loss protocol. This substance is primarily used in medicine for reproductive health and hormone regulation.
The Role of Human Chorionic Gonadotropin
HCG is a complex hormone produced primarily by the syncytiotrophoblast, which are cells surrounding the early embryo that eventually form the placenta. This substance is often called the “pregnancy hormone” because its presence in blood and urine is the basis for most at-home pregnancy tests. HCG’s major biological function is to interact with the luteinizing hormone-choriogonadotropin (LHCG) receptor in the ovary.
This interaction promotes the maintenance of the corpus luteum, a temporary gland that forms in the ovary after ovulation. The corpus luteum is then stimulated to produce high levels of the hormone progesterone during the first trimester of pregnancy. Progesterone is necessary to enrich the uterine lining, ensuring the uterus can sustain the developing fetus until the placenta is fully formed and takes over hormone production.
Established Medical Applications
In medical practice, HCG is an injectable prescription drug approved by the Food and Drug Administration (FDA) for specific conditions, primarily related to fertility and hormone balance. In women, HCG is used in conjunction with other fertility drugs to induce ovulation. Because HCG is structurally similar to luteinizing hormone (LH), it acts as a surrogate for the natural LH surge, which triggers the final maturation and release of an egg from the ovary. This is commonly referred to as a “trigger shot” in procedures like in vitro fertilization (IVF).
The hormone also has approved uses for men and boys related to androgen production. In males, HCG stimulates the Leydig cells in the testes to synthesize testosterone and other androgens. This mechanism is used to treat hypogonadotropic hypogonadism, a condition where the testes fail to produce enough testosterone and sperm due to a problem with pituitary gland signaling. Furthermore, HCG injections are sometimes administered to pre-pubertal boys to encourage the descent of testicles that have not naturally dropped into the scrotum, a condition known as cryptorchidism.
The Unapproved Weight Loss Protocol
The controversial use of HCG stems from a weight loss protocol that combines the hormone with a severely restricted diet. This protocol, first introduced in the 1950s, instructs users to take HCG while strictly limiting caloric intake to an extremely low level, often around 500 calories per day. Proponents of the diet claim that the HCG injections or drops work to “reset” the metabolism, target abnormal fat stores, and significantly reduce the hunger and discomfort associated with such a drastic calorie reduction.
However, the scientific consensus firmly rejects these claims, finding no substantial evidence that HCG increases weight loss beyond what is achieved solely by the severe caloric restriction. Numerous double-blind studies comparing subjects on the 500-calorie diet with HCG against those on the same diet with a placebo found no statistically significant difference in weight loss, body fat redistribution, or hunger ratings between the two groups. The weight loss observed is a direct result of near-starvation, not the hormone itself.
Claims that HCG helps prevent the loss of muscle mass are also unsubstantiated by scientific evidence. Because the hormone is ineffective for weight loss, its use in this context simply adds unnecessary risk to an already potentially dangerous dietary regimen.
Risks, Side Effects, and Regulatory Status
HCG is a potent prescription drug, and its use, even for approved indications, carries a risk of side effects. Common reactions include headaches, irritability, fatigue, and pain or swelling at the injection site. However, the hormone can also lead to more serious health concerns.
In women undergoing fertility treatment, a serious risk is Ovarian Hyperstimulation Syndrome (OHSS), where the ovaries become swollen and painful. For all users, a significant concern is the increased risk of blood clots, which can cause life-threatening events like stroke or pulmonary embolism. Other possible side effects include mood changes, depression, and in men, the growth of breast tissue known as gynecomastia.
The FDA has not approved HCG for any weight loss indication and actively warns consumers against using over-the-counter (OTC) HCG products. OTC HCG products are considered fraudulent and illegal because they are unapproved new drugs making unsupported claims. The agency emphasizes that coupling the hormone with a diet of 500 calories a day is dangerous, risking electrolyte imbalances, gallstone formation, and cardiac arrhythmias, especially without medical supervision.