AOD-9604: Fat Loss Peptide Evidence and Legal Status

AOD-9604 is a synthetic 16-amino-acid peptide based on the tail end of human growth hormone, designed to trigger fat burning without the broader effects of the full hormone. The name is shorthand for “Anti-Obesity Drug 9604”, and it was built specifically to lose weight in a clinical setting rather than as a research curiosity.

The molecule was developed in the 1990s by Professor Frank Ng and the team at Metabolic Pharmaceuticals, an Australian biotech spun out of Monash University. According to the FDA’s own advisory materials, AOD-9604 corresponds to amino acids 177 to 191 of human growth hormone with an extra tyrosine residue added at the N-terminal end, and it carries a disulfide bond between two cysteines at positions 7 and 14. That tyrosine and the disulfide bridge are what set it apart from the raw, unmodified growth hormone tail sold separately on the research-chemical market.

The bottom line: AOD-9604 is a purpose-built growth hormone fragment that was taken through human obesity trials, which separates it from most peptides sold for fat loss.

AOD-9604 is designed to stimulate lipolysis, the breakdown of stored fat, while suppressing lipogenesis, the laying down of new fat, without raising blood sugar or insulin-like growth factor 1 (IGF-1). This selectivity is the entire premise of the molecule: full-length growth hormone burns fat too, but it also drives insulin resistance and broad growth effects, whereas AOD-9604 was engineered to keep the fat-burning action and drop the rest.

In animal work, the lipolytic effect appears to run through the beta-3 adrenergic receptor. The clearest evidence comes from knockout studies: mice genetically lacking the beta-3 adrenergic receptor do not respond to the compound’s fat-burning action at all, and lean mice respond far less than obese ones. That points to a mechanism most active when there is excess fat and a working beta-3 pathway to act on. The effect also appears to be fasting-state dependent, performing best in a low-insulin environment, which is one reason real-world results would be hard to predict from the bench.

The bottom line: AOD-9604’s fat-loss mechanism is real in mice and runs through the beta-3 adrenergic receptor, but a mechanism in rodents is not the same as a clinical result in people.

AOD-9604 is unusual among fat-loss peptides because it has a genuine human clinical record, and that record is the strongest argument against it. Metabolic Pharmaceuticals ran the compound through roughly six human trials involving around 900 participants, and the largest and most rigorous of those failed.

Animal evidence

In genetically obese Zucker rats and ob/ob mice, AOD-9604 reduced body weight and body fat without the glucose-control problems normally seen with growth hormone, and it did so while leaving lean body mass largely intact. This preclinical signal, consistent across several rodent obesity models, was strong enough to justify moving the compound into human testing.

Human evidence

An early 12-week randomised controlled trial offered a glimmer of promise: participants on a 1 mg daily oral dose lost an average of about 2.6 kg, versus roughly 0.8 kg in the placebo group, a net difference of under 2 kg. That modest signal did not hold up at scale. The pivotal OPTIONS study, a 24-week double-blind Phase 2b trial that recruited 536 subjects, failed to reach its primary weight-loss endpoint. Metabolic Pharmaceuticals terminated the obesity programme in 2007.

Other research directions

After the obesity work ended, AOD-9604 was explored elsewhere. Researchers tested intra-articular injection, with and without hyaluronic acid, in a rabbit model of osteoarthritis, and the compound was briefly incorporated into an anti-cellulite cream that was later dropped for being costly and ineffective. None of these threads produced an approved therapy, and no completed human trials support any of them. The osteoarthritis line is the one genuinely distinct clinical signal AOD-9604 retains beyond fat loss, and even that sits at the animal stage.

Evidence tier	What was found	Strength
Rodent obesity models	Reduced weight gain and body fat; beta-3 receptor dependent	Promising preclinical
12-week human RCT	About 2.6 kg loss against 0.8 kg on placebo	Weak positive signal
OPTIONS Phase 2b (536 subjects)	Missed its primary endpoint; programme halted	Negative, pivotal
Osteoarthritis / cosmetic	Early animal and product work only	Exploratory

The bottom line: AOD-9604 has the rare distinction of being a fat-loss peptide that was properly trialled in humans and shown not to deliver.

AOD-9604 is not an approved medicine in any major market, and in the United States it has already been through formal review and rejected for compounding.

Jurisdiction	Status
United States	Removed from Category 2 in September 2024, then voted down by the advisory committee on 4 December 2024. Not approved and not on the 503A Bulks List.
United Kingdom	No UK marketing authorisation and not a controlled drug; supplied only as research-use-only material; banned for athletes under UK Anti-Doping rules.
Australia	Schedule 4 (prescription-only) under the Poisons Standard since 1 June 2015; possession without a prescription is an offence.
WADA (sport)	Named as a growth hormone fragment and prohibited at all times.

United States

AOD-9604 cannot be legally compounded under section 503A. It was one of five peptides removed from FDA Category 2 in September 2024 after their nominations were withdrawn, and it was then referred to the Pharmacy Compounding Advisory Committee. At the 4 December 2024 meeting, which reviewed the compound for the use of obesity, the committee voted against adding it to the 503A Bulks List, and a representative from drug giant Eli Lilly spoke against its inclusion during the open comment session. Because removal from Category 2 is not the same as permission to compound, and the committee declined to recommend it, AOD-9604 sits outside the legal compounding system. This is a separate track from the BPC-157 and TB-500 review taking place in 2026; AOD-9604 was handled in 2024. For the background, see the peptide reclassification tracker, the explainer on how the FDA categories work, and the overview of whether peptides are legal in the US.

One persistent claim deserves correction. AOD-9604 is frequently marketed citing a self-affirmed “Generally Recognized as Safe” status for use as a food ingredient at up to 1 mg per day. That is a manufacturer-driven food-ingredient claim, not a drug approval, and it does not authorise the compound as a weight-loss treatment. The FDA’s stated rationale for restricting it cited concerns over immunogenicity, peptide-related impurities, and limited safety information.

United Kingdom

AOD-9604 holds no UK marketing authorisation, and there is no lawful route to supply it for human use, with the UK lacking any compounding pathway equivalent to the US system. It circulates only as research-grade material and is off-limits to competing athletes. The wider framework is set out in our guide to whether peptides are legal in the UK.

Australia

AOD-9604 has been a Schedule 4 prescription-only substance under the Poisons Standard since 1 June 2015. It also holds a place in Australian sporting history: it was one of the substances injected into players during the Essendon Football Club supplements saga, though the bans that followed were ultimately tied to thymosin beta-4 rather than AOD-9604 itself. That episode is covered in our guides on whether peptides are legal in Australia and on TB-500 and thymosin beta-4.

The bottom line: AOD-9604 has already failed the one US regulatory test that matters, with the advisory committee declining to recommend it for compounding.

AOD-9604 was generally well tolerated in its clinical trials, with the developers reporting no serious adverse events across roughly 900 participants and, in particular, none of the glucose and IGF-1 disruption associated with growth hormone. On paper, that is a clean short-term safety profile, and it is the strongest claim vendors can honestly make.

There are important caveats, and they are the part of the risk picture that rarely makes the sales copy. The trial data are short-term, the compound was never studied for long-term use because the obesity programme was halted, and “well tolerated but ineffective” is not a reason to use something. More urgently, the AOD-9604 sold today does not come from those clinical batches. It is supplied as unregulated research-use-only material, where contamination, mislabelling, incorrect content, and the absence of quality control are real risks. Anyone evaluating a product should understand how to read a certificate of analysis and how to judge a vendor’s credibility, because the protections that applied to the trial product do not apply to the grey market.

The bottom line: AOD-9604 looked safe in trials, but it was shelved for not working, and today’s research-grade product carries unverified quality.

Is AOD-9604 the same as HGH Fragment 176-191?

No. AOD-9604 is a stabilised version of that fragment, carrying an added tyrosine and a disulfide bond between cysteines at positions 7 and 14. The clinical trials were run on AOD-9604, not on the unmodified fragment, so the two should not be treated as interchangeable despite being sold that way.

Why was AOD-9604’s development stopped?

Because the pivotal 24-week OPTIONS trial in 536 subjects did not hit its primary weight-loss endpoint. After an earlier short trial showed only a small advantage over placebo, the larger study confirmed the effect was too weak to support an obesity drug, and the developer ended the programme.

Does AOD-9604 have FDA approval because of its GRAS status?

No. A self-affirmed food-ingredient claim is not the same as drug approval. The FDA has not approved AOD-9604 to treat obesity or any other condition, and it cited safety and impurity concerns when it restricted the compound.

Will AOD-9604 be reviewed again like BPC-157?

There is nothing scheduled. Unlike BPC-157 and TB-500, which face a fresh advisory review in 2026, AOD-9604 already had its hearing and was rejected. A return to the agenda would require a new sponsor and likely new clinical data.

AOD-9604 sits in a cluster of compounds marketed for fat loss with very different evidence behind them. HGH Fragment 176-191 is the unmodified parent it was built from and the source of most confusion. The growth hormone secretagogues CJC-1295 and ipamorelin went through the same 2024 advisory review. 5-Amino-1MQ is another fat-loss compound with a different mechanism and even thinner human data. The approved GLP-1 medicines, semaglutide, tirzepatide, and the investigational retatrutide, are the relevant contrast, with the large, positive human weight-loss trials AOD-9604 never produced. For the wider category, see our overview of fat-loss and GLP-1 compounds.

There is no active obesity-drug development programme for AOD-9604. After the advisory committee’s vote, its US compounding pathway is closed, and unlike the peptides under review in 2026, it has no scheduled return to the regulatory agenda. Interest persists mainly because the older food-ingredient claim and the “no serious side effects” trial headline still circulate online, often without the crucial detail that the programme was abandoned for lack of efficacy. Barring a new sponsor running fresh, larger, and longer human trials, the scientific story of AOD-9604 as a weight-loss agent is effectively over, and the only live thread is its early-stage osteoarthritis research.

The bottom line: AOD-9604’s development is dormant, and nothing on the current regulatory calendar suggests that will change.