AOD-9604: The "Fat-Loss Fragment" and What Trials Found

AOD-9604 is usually sold with one phrase attached: "the fat-burning part of growth hormone, without the side effects." It is a tidy story. The trouble is that the company that developed it ran the trials that would have proved it, and then stopped.

If you have searched for AOD-9604, you have probably found two kinds of pages: vendors quoting animal results as if they happened in people, and forum threads full of before-and-after claims no one can check. Neither tells you what happened when the molecule was put through proper human trials. That history is on the public record, and it is more useful than anything on a product page.

What AOD-9604 actually is

Human growth hormone is a 191-amino-acid protein. It does many things at once: it drives growth in children, affects muscle and bone, raises blood sugar, and encourages the breakdown of stored fat. Researchers in Australia in the 1990s were interested in whether the fat-mobilizing effect could be separated from the rest, especially the effects on blood sugar and tissue growth that make growth hormone a poor weight-loss drug.

Their approach was to take a short section from the end of the molecule, the region thought to carry the fat-related activity, and make a modified version of it. The result was a 16-amino-acid peptide given the code name AOD9604 (AOD stood for "anti-obesity drug"). You will also see a closely related fragment sold as "hGH 176-191". The two are sometimes treated as interchangeable online; they are not identical molecules, and the anti-doping list names both.

The appeal was obvious. A drug that encouraged fat breakdown without raising IGF-1 or disturbing insulin sensitivity would have been valuable. The question was whether it did that in people, at a dose that mattered.

What the animal studies found

The early work was promising in the way early work often is. A study by Ng and colleagues, published in Hormone Research in 2000, gave AOD9604 by mouth to obese Zucker rats, a strain bred to become obese, for 19 days. Treated rats gained less than half as much weight as untreated controls, their fat tissue showed more fat-breakdown activity, and, unlike full growth hormone, the fragment did not appear to worsen insulin sensitivity.

That is a real finding. It is also a finding in a genetically obese rat strain, over less than three weeks, and results like it are the starting point for drug development rather than the end of it. Many compounds that change body weight in rodents do little in humans. The only way to find out is to run human trials, and in this case they were run.

What happened in the human trials

AOD9604 was developed commercially by an Australian company, Metabolic Pharmaceuticals. A 2014 review of its safety and metabolism in the Journal of Endocrinology and Metabolism (Moré and Kenley) summarizes the program: six human clinical trials, including intravenous and oral pilot studies and two oral phase 2b studies in adults with obesity.

In the earlier trials, there was a signal. Participants taking AOD9604 in a 12-week study lost, on average, a little under 2 kg (roughly 4 pounds) more than those on placebo. Modest, but enough to justify a bigger trial.

The later, larger work was the test that counted. According to that 2014 review, the weight-loss effect seen in the initial trials was not seen in the last study, which built in an intensive diet and exercise program, the setting any real obesity treatment is used in. Development of AOD9604 as an obesity drug was halted in 2007 after that disappointing 24-week trial.

Put plainly: the developer, with more reason than anyone to want AOD-9604 to work and access to all of the data, did not take it forward.

What about safety?

The same review reports that AOD9604 was well tolerated in those human studies, with no serious safety concerns identified. That is worth stating fairly. It is also worth stating what it does and does not mean. Those trials used a pharmaceutical-grade product, mostly by mouth, over weeks to months, in screened volunteers under monitoring. They tell you little about an injectable product of unknown origin used for an open-ended period by someone who was never screened.

After the obesity program ended, the ingredient was repositioned for food and supplement uses, and the review describes it receiving "generally recognized as safe" (GRAS) status for use in foods. GRAS is a food-ingredient concept. It says nothing about whether an injection is appropriate, effective, or approved, and it is sometimes quoted in marketing as though it did.

Why the story is still told the way it is

If AOD-9604 failed its key trial nearly two decades ago, why is it still marketed as a fat-loss peptide? A few reasons.

• The mechanism sounds right. "The fat-burning fragment of growth hormone" is a compelling sentence, and mechanism stories are easy to believe even when outcome data disagree.
• Early results get quoted, later ones don't. The rat data and the small early human signal are cited. The 24-week result rarely is.
• Weight loss is hard to attribute. People who start a peptide usually change their diet, exercise and attention at the same moment. If they lose weight, the peptide gets the credit. That is exactly the confounder a placebo-controlled trial is built to remove, and in the one designed to remove it, the effect did not hold.
• The GLP-1 era raised demand. As semaglutide and tirzepatide became hard to get or expensive, interest spilled over to anything described as a metabolic peptide.

Is AOD-9604 legal, and can a pharmacy make it?

AOD-9604 is not FDA-approved for any indication. That part is simple.

Whether a US pharmacy may compound it is less simple, because it depends on FDA's bulk drug substance framework, which has been moving. In late 2025, legal commentators were noting that FDA had proposed not to include AOD-9604 on the list of bulk substances that 503A pharmacies may use, citing safety concerns. In 2026, HHS announced it would revisit peptide restrictions, and FDA moved several peptides out of the category it uses for substances raising significant safety risks so they could be reviewed. Being moved for review is not the same as being cleared for compounding.

AOD-9604 was not one of the seven substances FDA's Pharmacy Compounding Advisory Committee voted on in July 2026. For what that meeting did and did not decide, see the July 2026 peptide vote, explained.

The honest position is that AOD-9604's regulatory status has been in flux, and you should not rely on a website, including this one, for where it stands today. A clinician should be able to tell you, name the pharmacy involved, and explain the legal basis. These rules change; verify current status with FDA or ask your prescriber to show you. Our overview of peptide regulatory status explains the framework.

Athletes: AOD-9604 is prohibited by name

The World Anti-Doping Agency's 2026 Prohibited List names "growth hormone fragments, e.g. AOD-9604 and hGH 176-191" in section S2 (peptide hormones, growth factors, related substances and mimetics). S2 substances are prohibited at all times, in and out of competition. WADA had previously stated that AOD-9604 was a substance still in development and not approved for therapeutic use by any government health authority.

If you compete in any sport that follows the WADA Code, including many college and amateur events that adopt USADA rules, AOD-9604 carries real risk to your eligibility regardless of how it is labeled or where you got it. Our guide to peptides and drug testing covers this in detail.

If weight is the real goal, what does have evidence?

The contrast with AOD-9604 is striking. Several peptide medicines for chronic weight management have been through large, long, placebo-controlled trials and FDA review. Semaglutide and tirzepatide are both peptides, and their pivotal obesity trials ran for well over a year in thousands of adults. They have real side effects and real limitations, including what happens when people stop, but their evidence is of a different order.

For a wider look at the options, including which peptide approaches have human data and which are still animal-stage, read our pillar on peptides for weight loss beyond GLP-1s, and the complete GLP-1 guide.

A good clinician will also look at things a peptide cannot fix: thyroid function, sleep, medications that promote weight gain, blood sugar, and whether an FDA-approved medicine is appropriate. If you want that kind of assessment, our peptide therapy consultations start with your history and labs rather than a product list, and sometimes end with the conclusion that a peptide is not the right tool.

Common questions

Does AOD-9604 work for fat loss?

In obese rats it reduced weight gain. In early human trials there was a small effect versus placebo. In the larger 24-week trial that followed, the effect was not seen, and development for obesity was stopped in 2007. There is no good human evidence that it produces meaningful fat loss.

Is AOD-9604 FDA-approved?

No. It has never been approved by FDA for any use. Whether a pharmacy may compound it has shifted over time; ask a clinician for its status today and verify with FDA.

Is AOD-9604 the same as growth hormone?

No. It is a short, modified fragment of the growth hormone molecule. It was designed specifically to avoid growth hormone's broader effects, such as raising IGF-1. That also means claims borrowed from growth hormone research do not transfer to it.

Will AOD-9604 show up on a drug test?

Anti-doping laboratories test for prohibited substances, and AOD-9604 is named on WADA's Prohibited List. Whether a particular test detects it depends on the test, but the rule applies whether or not you are caught: using it is an anti-doping violation for athletes under the WADA Code.

Can I get AOD-9604 through a telehealth clinic?

Some clinics offer it. Before accepting, ask what its current regulatory status is, which licensed pharmacy would prepare it, and what human evidence supports using it for your goal. Our questions to ask any peptide provider give you a script. If you would rather start with an assessment than a product, you can book a consultation with one of our clinicians.