hCG (human chorionic gonadotropin)

What hCG is

Human chorionic gonadotropin is a hormone that the placenta produces during pregnancy. Every pregnancy test detects exactly this hormone. It resembles luteinizing hormone, that is, the signal that tells the ovaries to ovulate and, in men, tells the testes to produce testosterone.

This gives rise to the approved uses. In fertility treatment, hCG triggers ovulation. In men with a certain form of testosterone deficiency, it gets their own production going. It is also used in boys with undescended testes. These are well-supported, sensible uses of a perfectly ordinary medicine that has been prescription-only for decades.

Where the weight-loss regimen comes from

In the mid-1950s, the British physician Albert Simeons treated boys with undescended testes with hCG in Rome. He believed he observed that their body shape changed in the process. He turned this into a weight-loss regimen: a daily hCG injection plus a diet of 500 kilocalories a day.

500 kilocalories are about a quarter of what an adult needs. Simeons claimed that the hCG made the body target fat reserves instead of muscle, and that one felt no hunger despite this amount. The people treated did indeed lose weight. On 500 kilocalories, everyone loses weight. The effect is real, the attribution is wrong.

Why the fallacy persists

The business model rests not on the hormone but on the diet. Anyone who does the regimen loses 2 kilograms a week, sometimes more. They injected, they starved, they lost weight. To which of the two do they attribute the success? To the one that feels like medicine.

Anyone can starve; that is not a service you can charge money for. An injection is a product. That is why hCG is the cleanest example of a fallacy that reaches far beyond this topic: when two things happen at the same time and one of them looks like the cause, we stop asking. The useful counter-question is: if a treatment only works together with a drastic measure, which of the two is doing the work?

The use that holds up pharmacologically

There is a second use, and it makes sense. Anyone who takes testosterone from outside shuts down their own signal. The testes no longer receive instructions and stop working, they shrink, fertility suffers. hCG mimics exactly this missing signal and keeps operations going.

Physicians use it in this context, mostly outside the official approval. It has nothing to do with weight loss; it is the same active substance for an entirely different question. Anyone who considers hCG sensible here has not gained an argument for the diet. Conversely, the refuted diet does not discredit this use.

In humans, this has been shown in small studies. In a randomized study with 29 healthy men, low-dose hCG during testosterone kept intratesticular testosterone within the normal range over three weeks; without hCG it fell by 94 percent (Coviello 2005). In a retrospective analysis of 26 men on testosterone therapy plus hCG, none became azoospermic, semen parameters remained stable, and 9 men fathered a child during this period (Hsieh 2013). Whether hCG reliably preserves fertility during testosterone therapy, however, has not been tested in any controlled study.

Drops without a prescription

Drops that require no prescription are also sold. hCG is a large protein molecule, and a protein that is swallowed is digested like any other. It does not reach the blood as a hormone. Many of these drops are also homeopathically diluted, so they contain practically nothing anyway. The authorities in the US have taken action against them. Anyone who takes such drops is in reality simply doing the 500-calorie diet.

What the studies show

Analysis of 24 studies, British Journal of Clinical Pharmacology 1995

In 1995, an analysis was published that brought together 24 studies on hCG for weight loss, 14 of them randomized, with a total of 605 participants. In 12 of the 14 randomized studies, weight loss under hCG was no greater than under placebo or under the diet alone. The paper’s concluding sentence: there is no scientific evidence that hCG causes weight loss, redistributes fat, keeps hunger at bay or produces a feeling of well-being, which is why its use as a weight-reduction therapy should be regarded as inappropriate. This analysis is 31 years old.

What hCG does not do

For weight loss, it is not that little has been shown; the opposite has been shown. The three promises of the regimen — targeted fat loss, protection of muscle, absence of hunger — are precisely the points that the 1995 analysis explicitly rejects. This is not a thin body of data, it is a line drawn under the matter, and it was drawn 31 years ago.

Status, approval and legal

hCG is a prescription medicine and has been approved for decades: for triggering ovulation in fertility treatment, in certain forms of testosterone deficiency and in undescended testes. Its use to maintain testicular function during testosterone therapy mostly takes place outside this approval. hCG is not approved as a weight-loss drug. The authorities in the US have taken action against over-the-counter, often homeopathically diluted hCG drops, and the US drug regulator has explicitly warned that a calorie intake in the range of 500 kilocalories a day can be fatal. In sport, hCG is prohibited at all times for men; the 2026 WADA list includes it under S2.2.1.

Safety

Two risks that must be considered separately. The hormone itself is not harmless: menstrual cycle disturbances, breast tenderness up to breast enlargement in men, mood changes and an increased risk of blood clots. In women undergoing fertility treatment, ovarian hyperstimulation is a known, serious complication, which is why the hormone belongs in a physician’s hands. The second risk is the regimen: 500 kilocalories over weeks is not a diet but malnutrition. Documented are muscle loss, gallstones, which occur more often with very rapid weight loss, electrolyte disturbances and resulting heart rhythm disorders.

Sources

• Lijesen et al., Br J Clin Pharmacol 1995 (analysis of 24 studies on hCG and weight loss)
• Simeons, Lancet 1954 (weight-loss protocol with hCG and a 500-kilocalorie diet)
• US drug regulator: warning about very low calorie intake and action against over-the-counter hCG products
• FDA prescribing information Chorionic Gonadotropin, DailyMed (approved uses: ovulation induction, testosterone deficiency, undescended testes)
• Coviello et al., J Clin Endocrinol Metab 2005 (randomized, hCG during testosterone, 29 men)
• Hsieh et al., J Urol 2013 (retrospective, testosterone therapy plus hCG, 26 men)
• WADA, Prohibited List 2026, section S2.2.1