HCG (human chorionic gonadotropin): what the evidence shows

Q: Does the HCG diet work?

The 500-calorie diet works; the injections do not add anything. In controlled trials HCG produced no more weight loss, no less hunger and no different fat distribution than placebo. Losing weight on 500 calories a day is not evidence that the hormone did it.

Q: Is HCG legal?

Yes, as a prescription medicine for fertility and hypogonadism. Over-the-counter and homeopathic 'HCG diet' products are unapproved, and in the US the label must state it has no proven weight-loss effect.

Q: Is HCG used with testosterone therapy?

It is prescribed clinically to preserve testicular function and fertility during testosterone therapy. That is a decision for a clinician and outside what this site covers.

What the human research shows

Two entirely separate stories under one name. The fertility and hypogonadism indications are approval-grade medicine. The weight-loss claim was tested repeatedly, failed repeatedly, and is graded A for the strength of the evidence that it does not work.

Evidence profile0–5

Metabolic & weightA0.0
Cardiovascular—0.0
Muscle & growth—0.0
Healing & repair—0.0
Neuro & sleep—0.0
Immune & inflammation—0.0
Sexual & hormonalA3.3
Skin & appearance—0.0
Ageing & longevity—0.0

Each score is confidence × effect size, taken from the best-evidenced benefit in that domain: the grade (A–D) sets the confidence, the measured effect sets the size. Hover a domain to see the outcomes behind it. Adverse effects are excluded and listed separately below.

Outcome	Grade	Effect size	Human studies	Where the evidence comes from
Ovulation induction and fertility	AEstablished	Large	Approval-grade programmes	Triggering final oocyte maturation is HCG's licensed use and standard practice in assisted reproduction worldwide.2
Testosterone stimulation in men	AEstablished	Moderate	Approval-grade	Licensed for hypogonadotropic hypogonadism, where it stimulates the testes directly; used clinically to maintain testicular function and fertility.2
Weight loss	AEstablished	Not measurable	Meta-analysis of 8 controlled trials	Repeatedly tested against placebo alongside the same very-low-calorie diet. The diet produces the weight loss; HCG adds nothing measurable to weight, hunger, fat distribution or wellbeing.1

AMultiple good human trials, consistentBSome human trials, mostly consistentCFew or weak human studiesDAnimal or anecdotal onlyeffect size · red = adverse

Literature searched to 3 September 2026. Human studies only; animal and cell work informs the mechanism section and nothing else.

Registered trials

ClinicalTrials.gov lists 54+ interventional studies naming HCG (human chorionic gonadotropin) as an intervention — 28 completed, 3 recruiting, and 14 with results posted to the registry.

A registration is not a result. Anyone can register a study, and many never report — so this list shows what has been attempted, not what has been shown. The graded evidence above is the answer to whether something works.

Study	Phase	Status	Participants	Sponsor	Results
Triggering of Final Oocyte Maturation With GnRHa (Buserelin) in GnRH Antagonist CyclesNCT00627406 · started Jan 2009	Phase 4	Completed	384	Regionshospitalet Viborg, Skive	Posted
Trial Comparing hCG Triggering Versus hCG Associated With GnRH AgonistNCT01607203 · started Nov 2011	Phase 4	Completed	120	AZ Jan Palfijn Gent	Posted
Study to Examine Effect of Recombinant Luteinizing Hormone (r-Lh) and Recombinant Human Chorionic Gonadotropin (r-hCG) for Ovarian Stimulation in Assisted Reproduction Techniques (ART)NCT01339299 · started Oct 2009	Phase 4	Completed	100	Regionshospitalet Viborg, Skive	Posted
Luveris® (Lutropin Alfa for Injection) in Women With Hypogonadotropic Hypogonadism (Luteinizing Hormone [LH] Less Than [<] 1.2 International Unit Per Liter [IU/L])NCT00328926 · started Mar 2006	Phase 4	Terminated	11	EMD Serono	Posted
PERgoveriS In Stratified Treatment for Assisted Reproductive TechniqueNCT01297465 · started May 2011	Phase 3	Completed	202	Merck KGaA, Darmstadt, Germany	Posted
Phase 3 Trial to Evaluate the Efficacy and Safety of COL-1620 Vaginal Progesterone GelNCT01863680 · started Jul 2013	Phase 3	Completed	178	Merck KGaA, Darmstadt, Germany	Posted
A Trial to Compare the Efficacy and Safety of Ovarian Stimulation With GONAL-f® and Luveris® Starting on Day 1 Versus Day 6 in Women Undergoing Assisted Reproductive TechniqueNCT01497197 · started May 2012	Phase 3	Terminated	174	Merck KGaA, Darmstadt, Germany	Posted
A Study Using Recombinant Human Luteinizing Hormone (r-hLH, Luveris®) in the Treatment of Chinese Women With Hypogonadotropic HypogonadismNCT01084265 · started Feb 2004	Phase 3	Completed	31	Merck KGaA, Darmstadt, Germany	Posted

46 further studies are registered. Participant counts marked * are the sponsor's estimate, not a final enrolment. Source: ClinicalTrials.gov, read directly from the registry and refreshed weekly.

What it is

HCG is a glycoprotein hormone produced in pregnancy — the hormone pregnancy tests detect. It acts on the same receptor as luteinising hormone, which is why it can substitute for the body's own ovulation and testosterone signals.

The HCG diet dates to a 1950s protocol pairing small daily injections with a 500-calorie-a-day diet. The diet alone would produce rapid weight loss in anyone; the question the trials asked was whether the injections added anything.

How it is thought to work

By binding the LH receptor it triggers ovulation in women and testosterone production in men. There is no established mechanism by which it would mobilise fat or suppress appetite, which is consistent with the trial results.

What is still unknown

Nothing substantial remains open on the weight question — it has been answered.
Optimal use alongside testosterone therapy for preserving fertility is an active clinical question, though outside what this site covers.

The molecule and how long it lasts

Identity

A glycoprotein hormone (two subunits, glycosylated) — no small-molecule record

Pharmacokinetics

Route: Intramuscular injection
Half-life: Not stated in the label
Licensed regimen (Pregnyl (chorionic gonadotropin)): Hypogonadotropic hypogonadism: 500-1,000 USP units three times weekly for 3 weeks then twice weekly for 3 weeks, or 4,000 USP units three times weekly for 6-9 months; ovulation induction: 5,000-10,000 USP units one day after the last gonadotropin dose

From the approved product's prescribing information: Pregnyl prescribing information (DailyMed) The regimen is the label's own wording, reproduced as a regulatory fact.

Regulatory status

European Union

Approved, prescription-only

Authorised for fertility indications and hypogonadotropic hypogonadism.

United States

Approved, prescription-only — weight-loss use prohibited on the label

FDA-approved for fertility and hypogonadism. Labelling must state that HCG has no proven effect on weight loss, fat distribution or hunger; homeopathic and over-the-counter 'HCG diet' products are unapproved and have been the subject of enforcement.

United Kingdom

Licensed, prescription-only

Licensed for fertility indications.

Australia

Registered, prescription-only

On the ARTG for fertility and hypogonadism.

Canada

Authorised, prescription-only

Authorised for fertility indications.

Sport (WADA)

Prohibited in males at all times

Prohibited for male athletes as a testosterone-stimulating agent.

Questions people actually ask

Does the HCG diet work?

The 500-calorie diet works; the injections do not add anything. In controlled trials HCG produced no more weight loss, no less hunger and no different fat distribution than placebo. Losing weight on 500 calories a day is not evidence that the hormone did it.

Is HCG legal?

Yes, as a prescription medicine for fertility and hypogonadism. Over-the-counter and homeopathic 'HCG diet' products are unapproved, and in the US the label must state it has no proven weight-loss effect.

Is HCG used with testosterone therapy?

It is prescribed clinically to preserve testicular function and fertility during testosterone therapy. That is a decision for a clinician and outside what this site covers.

One page per claimed effect

ADoes HCG (human chorionic gonadotropin) help with ovulation induction and fertility?Approval-grade programmes
ADoes HCG (human chorionic gonadotropin) help with testosterone stimulation in men?Approval-grade
ADoes HCG (human chorionic gonadotropin) help with weight loss?Meta-analysis of 8 controlled trials

References

1
Lijesen GKS, et al. The effect of human chorionic gonadotropin (HCG) in the treatment of obesity by means of the Simeons therapy: a criteria-based meta-analysis.Br J Clin Pharmacol, 1995;40:237–2438 controlled and 16 uncontrolled trials.
2
Chorionic gonadotropin prescribing information and approved indications.FDA / EMA product informationFertility and hypogonadism indications; required weight-loss disclaimer.
3
Young RL, et al. Chorionic gonadotropin in weight control: a double-blind crossover study.JAMA, 1976

Change log

2026-09-03Initial publication. Fertility and hypogonadism graded A; weight loss graded A for a well-established absence of effect.