Limited EvidencePeptide

AOD-9604

The growth hormone fragment

Growth Hormone Fragment (hGH 176-191)

Last updated: August 2026

Evidence Level: Limited Evidence

Mostly animal data or anecdotal reports, theoretical basis

Regulatory Status: Not approved as a drug anywhere. Added to the FDA's 503A Category 2 list in 2023, removed from Category 2 in September 2024, and not on the permitted 503A list. Sold as a gray-market "research chemical."

AOD-9604 is a 16-amino-acid fragment of human growth hormone, marketed for fat loss on the theory that it keeps growth hormone's fat-burning effect without its blood-sugar side effects. The theory is elegant. The problem is that when it was tested properly, in a 24-week trial of more than 500 people, it did not beat placebo, and development was abandoned.

How It Works

The idea behind AOD-9604 is genuinely clever, which is part of why it has stayed popular long after the data stopped supporting it.

Human growth hormone does several different things, and they are not all located in the same part of the molecule. Researchers at Monash University identified that the fat-burning activity seemed to live in the tail end of the protein, specifically amino acids 176 to 191. The blood-sugar and tissue-growth effects, which are the reasons growth hormone can cause insulin resistance and swelling, appeared to live elsewhere.

So the pitch was: take just that fragment. You get lipolysis, meaning the breakdown of stored fat, without the metabolic downsides of full growth hormone. It does not raise IGF-1, so in theory it also avoids the growth-promotion concerns that come with growth hormone therapy.

Why it did not work out. In cells and in obese mice, the fragment did increase fat breakdown and reduce fat accumulation. In a 12-week human trial, the results looked encouraging: about 2.6kg of weight loss versus 0.8kg on placebo. Then the compound went into a proper 24-week phase 2b trial in more than 500 people, and it did not separate from placebo on the primary endpoint. Metabolic Pharmaceuticals stopped developing it as an obesity drug in 2007.

That sequence, promising mechanism, promising small trial, then failure at scale, is one of the most common stories in drug development. It is also the exact sequence the peptide market tends not to mention.

Evidence by Outcome

Each claim below is rated using a GRADE-aligned five-tier system. Same molecule, different outcomes, different evidence.

Evidence at a glance

How we grade

Weight lossLow

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Weight lossLow certainty

Does not produce clinically meaningful weight loss in adults with obesity.

Population: Adults with obesity

Why this rating

The best-powered test of this compound, a 24-week trial in over 500 participants, failed to beat placebo on its primary endpoint, and the program was discontinued. That is the most informative result available. The tier is low rather than high because the failed trial was never published in full, so the effect estimate and its confidence interval cannot be independently examined. The direction of the evidence, however, is not ambiguous: this compound was tested properly and did not work.

GRADE downgrade factors applied

Publication bias: Suspicion that negative or null results were not published, inflating apparent effect.
Risk of bias: Methodological flaws in the studies (e.g. lack of blinding, allocation concealment, high attrition).

Supporting studies

Phase 2b obesity trial (Metabolic Pharmaceuticals)Randomized Controlled Trial
2007n=536
Primary weight-loss endpoint not met at 24 weeks. Development discontinued.
The weight-reducing effect of an orally active growth hormone fragment in obese subjectsRandomized Controlled Trial
International Journal of Obesity2004
A shorter 12-week trial reported about 2.6kg versus 0.8kg on placebo, a result the larger trial did not confirm.

Reviewed 2026-08-24· Designing Longevity EditorialHow we grade

Potential Benefits

Does not raise IGF-1, so it avoids the tissue-growth concerns associated with growth hormone therapy
Appeared well tolerated in the human trials that were run, with no serious safety signals reported
Increased fat breakdown in cell and animal models
A 12-week human trial showed modest weight loss versus placebo, though this was not confirmed at scale

Risks & Considerations

Failed its primary endpoint in a 24-week trial of more than 500 people, and development was abandoned
The failed phase 2b results were never published in a peer-reviewed journal, so the full data is not public
No approved product anywhere, meaning no manufacturing oversight, no purity guarantee, and no dose accuracy
Long-term safety in humans is unknown, because nobody kept studying it
Marketing frequently cites the positive 12-week trial without mentioning the larger failed one
Money spent here is money not spent on interventions that do have evidence

Dosing Information

There is no approved dose. Since the compound did not work in its pivotal trial, we are not going to publish a protocol for it. The numbers below are what the trials used, for reference only.

•Human obesity trials studied oral doses in the range of 1mg to 30mg daily
•Gray-market vendors typically sell it for subcutaneous injection at 300mcg per day, which does not correspond to any trial
•The mismatch between the doses studied and the doses sold should tell you something about how well grounded the marketing is

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Practical Tips

1The honest recommendation is to skip this one. A drug that misses its endpoint in a 500-person trial is not a hidden gem
2If a vendor cites the 12-week study without mentioning the failed 24-week phase 2b, treat that as a signal about the vendor
3If your goal is fat loss with evidence behind it, the GLP-1 class is where the data actually is
4AOD-9604 is sometimes marketed for joint and cartilage repair. That evidence is even thinner than the fat-loss evidence

Key Research

The weight-reducing effect of an orally active growth hormone fragment in obese subjects (12-week trial)

International Journal of Obesity, 2004

Reported about 2.6kg weight loss on AOD-9604 versus 0.8kg on placebo over 12 weeks. This is the trial most commonly cited in marketing.

Phase 2b obesity trial (Metabolic Pharmaceuticals)

2007

A 24-week trial in more than 500 people failed to meet its primary weight-loss endpoint. Detailed results were never published in a peer-reviewed journal. Development of AOD-9604 as an obesity drug was discontinued.

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Frequently Asked Questions

Does AOD-9604 actually work for fat loss?

The best available evidence says no. A 12-week trial showed modest weight loss, which is the study most vendors cite. But a larger 24-week phase 2b trial in more than 500 people failed to beat placebo on its primary endpoint, and the company developing it stopped the program in 2007. When a small positive trial is followed by a larger negative one, the larger one is usually closer to the truth.

What is AOD-9604?

AOD-9604 is a 16-amino-acid fragment of human growth hormone, corresponding to amino acids 176 to 191 of the full protein. It was designed to isolate growth hormone's fat-burning activity while leaving out the parts responsible for raising blood sugar and IGF-1. It is not approved as a drug in any country.

Is AOD-9604 legal?

It is not approved as a drug anywhere. The FDA added it to Category 2 of the interim 503A bulk substances list in 2023, flagging safety concerns, then removed it from Category 2 in September 2024. Removal from Category 2 is not the same as approval: it is not on the permitted 503A list either, which leaves it in a gray zone where it is neither authorized for compounding nor explicitly prohibited.

Is AOD-9604 safer than growth hormone?

In principle it should avoid growth hormone's main downsides, since it does not raise IGF-1 and did not cause the insulin resistance seen with full growth hormone. The trials that were run reported it as well tolerated. But "safe" and "useful" are different questions, and nobody has studied its long-term safety because development stopped nearly twenty years ago.

Why do clinics still sell AOD-9604?

Because the mechanism sounds convincing, the 2004 trial is genuinely positive, and the failed 2007 trial was never published in a journal, which makes it easy to leave out of the sales pitch. That combination lets a compound stay commercially alive long after the evidence turned against it.

What should I use instead of AOD-9604 for fat loss?

If you want a medication with real evidence, the GLP-1 class is where it is. Semaglutide averaged about 15% body-weight loss and tirzepatide about 21% in large phase 3 trials, both published in full and both FDA-approved. That is a different order of magnitude from anything AOD-9604 ever showed, even in its positive trial.

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