Peptide Evidence Index

AOD-9604

Evidence last reviewed: September 2026

Quick answers

What is it?: AOD-9604 is a synthetic 16-amino-acid piece of human growth hormone (the tail end of the molecule, plus one extra amino acid), designed to trigger fat breakdown without growth hormone's other effects. It has never been approved as a medicine anywhere.
Why are people interested in it?: It's marketed heavily for weight loss, and unlike most peptides in this library it was reportedly taken into real human obesity trials in the 2000s, so people want to know what those trials found.
What has actually been studied?: Mouse studies of weight and fat loss, a rabbit model of knee cartilage injury injected directly into the joint, and lab-based anti-doping detection work; reviews from the mid-2000s describe human Phase II obesity trials but no results from them were ever published.
How strong is the evidence?: Animal-only in practice. No peer-reviewed human trial result for AOD-9604 exists anywhere in the literature or on ClinicalTrials.gov, despite trade accounts describing human trials having been run.
What don't we know yet?: Whether the reported 2000s human obesity trials ever produced a result and why it was never published, whether the mouse fat-loss effect occurs in people, and what an unregulated vial actually contains.
Where can I read the original research?: Sources at the bottom of this page: Halford, "Obesity drugs in clinical development," Current Opinion in Investigational Drugs 2006; Heffernan et al., Endocrinology 2001.

Plain-English overview

AOD-9604 is a synthetic 16-amino-acid fragment modeled on the tail end of human growth hormone, with an added tyrosine, isolated by an Australian biotech in the 1990s because it appeared to trigger fat breakdown in animals without growth hormone's other effects. It is not approved as a medicine anywhere and has no drug approval in the United States, the EU, the UK, or Australia. Separately, it has been given a GRAS (Generally Recognized As Safe) determination for use as a food ingredient in the United States, which is a food-safety classification, not proof that it works, and not a drug approval. Reviews from the mid-2000s describe AOD-9604 as a human growth hormone fragment undergoing clinical development for obesity, implying real human trials were run, but no peer-reviewed result from those trials has ever appeared in the literature, and no trial is registered on ClinicalTrials.gov. It is prohibited at all times in competitive sport by the World Anti-Doping Agency.

What researchers are studying it for

obesity / fat loss (reported human trials, results not published)
adipose tissue breakdown (animal)
intra-articular joint/cartilage injection (animal)

Current evidence level

Mixed human evidence

Regulatory status: Not an approved medicine. Evidence strength and approval are scored separately; approval is a regulatory decision about a specific use, not a measure of how much research exists.

Human research

No AOD-9604 trial of any kind is registered on ClinicalTrials.gov. A 2006 review in Current Opinion in Investigational Drugs by Halford grouped AOD-9604 with other anti-obesity compounds "undergoing clinical development," which describes an active company trial program, but this describes only that trials were reportedly happening, not what they found. This review could not locate any peer-reviewed paper reporting a human weight, fat-mass, or safety outcome for AOD-9604, for obesity or any other purpose, despite nearly two decades having passed since the mid-2000s reviews. What does exist in the human literature is a 2014 anti-doping laboratory paper that developed methods to detect AOD-9604 in blood and urine and documented real seizures of AOD-9604 products in the US and Europe, evidence of human use, but not of any benefit. No human dose-finding or efficacy study has ever been published for AOD-9604, at any dose, for any use.

Animal and preclinical research

In a 2001 Endocrinology study, AOD-9604 and full-length human growth hormone both reduced body weight and body fat in obese mice after 14 days of injections, and increased levels of a specific fat-cell receptor (the beta-3 adrenergic receptor); when that receptor was genetically knocked out in mice, the chronic weight-loss effect disappeared, though AOD-9604 still briefly increased energy expenditure and fat oxidation in an acute test. In an unrelated line of research, a 2015 study injected AOD-9604 directly into the knee joint of rabbits with induced osteoarthritis and found it reduced cartilage damage and shortened lameness, especially when combined with hyaluronic acid, a completely different application from weight loss, and again not tested in humans.

Major findings

In a 2001 mouse study, AOD-9604 reduced body weight and body fat after 14 days of treatment, similarly to full-length human growth hormone, an effect tied to the beta-3 adrenergic receptor in fat cells.
When that receptor was genetically knocked out in mice, AOD-9604's chronic weight-loss effect disappeared, though it still produced a short-term increase in energy expenditure and fat burning.
A 2015 rabbit study found that injecting AOD-9604 directly into an osteoarthritic knee joint reduced cartilage damage and shortened lameness, an effect strengthened when combined with hyaluronic acid.
Reviews from the mid-2000s describe AOD-9604 as a human growth hormone fragment "undergoing clinical development" for obesity, implying real Phase II human trials were conducted.
No peer-reviewed paper reporting a human result for AOD-9604, for weight, fat mass, or any other outcome, has ever been located, and no AOD-9604 trial is registered on ClinicalTrials.gov.
A 2014 anti-doping laboratory paper built detection methods for AOD-9604 and documented its presence in confiscated black-market products in the US and Europe.
A 2026 Sports Medicine review classifies AOD-9604 among unapproved, direct-to-patient peptides marketed for musculoskeletal and performance uses without human trial support.

What has not been established

Whether the human obesity trials reportedly run in the 2000s ever produced a result, and why, if they did, it was never published.
Whether AOD-9604's fat-loss effect in mice occurs in people at all.
What the GRAS food-safety determination was based on, and whether it has any bearing on effectiveness for weight loss.
Whether the joint-protective effect seen in rabbit knees has any relevance to humans.
What long-term use does, since no human study of any duration could be located.
What an unregulated vial sold online as AOD-9604 actually contains.

Important limitations

The only completed human-relevant literature is a laboratory detection method paper, not a therapeutic trial; it shows AOD-9604 can be found in blood and urine, not that it does anything beneficial.
Reviews describing human obesity trials in the 2000s do not cite a primary data source, so the description of "trials underway" cannot itself be independently verified beyond the review's own text.
No dose has ever been validated in a human study; figures circulating online come from mouse-to-human weight conversions, not human data.
The mouse and rabbit findings come from a small number of published studies, not a replicated research program.
No registry entry exists to track whether any AOD-9604 human trial is ongoing, completed, or abandoned.

Regulatory status

AOD-9604 is not approved as a medicine for obesity or any other condition in the United States, the EU, the UK, or Australia. It has a GRAS (Generally Recognized As Safe) food-ingredient determination in the US, which is a food-safety classification, not a drug approval, and does not require proof that it does anything for weight loss. It is prohibited at all times in competitive sport by the World Anti-Doping Agency, as a human growth hormone fragment.

Primary research sources

Halford JCG, "Obesity drugs in clinical development": Current Opinion in Investigational Drugs 2006;7(4):312-8; PMID 16625817
Heffernan M, Summers RJ, Thorburn A, et al., "The effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism following chronic treatment in obese mice and beta(3)-AR knock-out mice": Endocrinology 2001;142(12):5182-9; PMID 11713213, DOI 10.1210/endo.142.12.8522
"Detection and in vitro metabolism of AOD9604": Drug Testing and Analysis 2014; PMID 25208511, DOI 10.1002/dta.1715
Kwon DR, Park GY, "Effect of Intra-articular Injection of AOD9604 with or without Hyaluronic Acid in Rabbit Osteoarthritis Model": Annals of Clinical and Laboratory Science 2015;45(4):426-32; PMID 26275694
"Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance": Sports Medicine 2026; PMID 41966639, DOI 10.1007/s40279-026-02437-0

Full evidence entry (complete data, registry records, dosing evidence)

Mixed human evidence

Controlled human trials exist and disagree

At a glance

Also known as: hGH Fragment 176-191, hGH Fragment 177-191, AOD9604, Anti-Obesity Drug 9604
Class: Synthetic 16-amino-acid peptide, a modified fragment of human growth hormone
Derived from: The C-terminal fragment of human growth hormone (amino acids 176/177-191), with an added tyrosine residue, isolated by an Australian biotech in the 1990s for its fat-breakdown (lipolytic) activity — without, its developers argued, the growth-promoting or blood-sugar-raising effects of full-length growth hormone
Registered human trials: 0
…with published results: 0
Largest human trial: None with peer-reviewed published results. Trade and industry accounts describe Phase II human obesity trials conducted in the 2000s, but no efficacy data for AOD-9604 appears in the indexed peer-reviewed literature, and no AOD-9604 trial is registered on ClinicalTrials.gov.
Studied for: obesity / fat loss (reported human trials, results not published), adipose tissue breakdown (animal), intra-articular joint/cartilage injection (animal)
Dosing evidence: No human dose establishedNo peer-reviewed human dose-finding data could be located. Reviews from the mid-2000s describe AOD-9604 as being in human clinical development for obesity, but this review found no published trial results and no registered trial specifying what dose was tested or what it did.
Regulatory status: Not approved as a medicine for obesity or any other condition in the United States, the EU, the UK, or Australia (its country of origin). Separately, AOD-9604 has been given a GRAS (Generally Recognized As Safe) determination for use as a food ingredient in the United States. GRAS is a food-safety classification — it means a substance is considered safe to consume at its intended level in food. It is not a drug approval, does not require any proof the substance does anything for weight loss, and does not put AOD-9604 through the efficacy review that FDA drug approval requires. The two are frequently confused; they are not the same thing.
Anti-doping status: Prohibited at all times by the World Anti-Doping Agency, as a human growth hormone fragment (S2); anti-doping laboratories have built detection methods specifically for it and identified it in confiscated products

What it is

AOD-9604 is a synthetic 16-amino-acid piece of human growth hormone — specifically, the tail end of the molecule, with one extra amino acid attached. Researchers in Australia isolated this fragment in the 1990s because, in animal studies, it seemed to trigger fat breakdown without the growth-promoting or blood-sugar effects of full-length growth hormone.

It is not approved as a medicine anywhere, and it is prohibited in competitive sport at all times.

What the studies actually found

In animals — mice, specifically — AOD-9604 and full-length growth hormone both reduced body weight and body fat after two weeks of treatment, an effect linked to changes in a specific fat-cell receptor (the beta-3 adrenergic receptor). That is real, published animal pharmacology, and it's the scientific basis for everything AOD-9604 has been developed and marketed for since.

What happened when this moved into humans is much less clear. Reviews from the mid-2000s describe AOD-9604 as a human growth hormone fragment "undergoing clinical development" for obesity, grouped alongside other anti-obesity drugs of that era. That describes a company actively running trials — but this review could not locate a single peer-reviewed paper reporting what those human trials found, for weight, fat mass, or any other outcome. Nearly two decades later, that gap has not been filled: no efficacy result for AOD-9604 in humans has ever appeared in the indexed medical literature.

Separately, in an unrelated line of animal research, injecting AOD-9604 directly into the joint reduced cartilage damage in a rabbit model of knee osteoarthritis — a completely different application from weight loss, and, again, not tested in humans.

What exists in humans

No AOD-9604 trial is registered on ClinicalTrials.gov, under searches for the compound itself or for the companies historically associated with its development. That is a real gap: if human obesity trials were conducted, as trade literature from the 2000s describes, their results were never made public through a peer-reviewed journal or a clinical trial registry that this review could locate.

What does exist in the human literature is almost entirely about detecting AOD-9604 as a doping agent — anti-doping laboratories have built assays to find it in blood and urine, and have documented seizures of AOD-9604 products in the US and Europe. That confirms real-world human use. It says nothing about whether it works.

No published human trial demonstrates that AOD-9604 causes weight loss, fat loss, or any other benefit.

What doses have been studied in humans

This review could not locate a published human dose-finding or efficacy study for AOD-9604 — for obesity or any other use. If Phase II human obesity trials were conducted, as industry reviews from the 2000s suggest, no dose, no result, and no outcome from those trials appears in the peer-reviewed literature or in any clinical trial registry.

That absence is itself the most important fact in this section. It means every dosing figure circulating online for AOD-9604 traces back not to a published human result, but to the mouse studies described above — scaled from a mouse's body weight to a person's using a standard conversion formula. That kind of conversion estimates a comparable exposure between species. It does not establish that the resulting amount does anything, or is safe, in a person.

What remains unknown

Whether the human obesity trials reportedly run in the 2000s ever produced a result, and if so, what it was and why it was never published
Whether AOD-9604's mouse-model fat-loss effect occurs in humans at all
What the GRAS food-safety determination was actually based on, and how it relates (or doesn't) to any claim of effectiveness
Whether the joint-injection effect seen in rabbits has any relevance to humans
What long-term use does — no human study of any duration could be located
What purity or content an unregulated vial sold online actually contains

Registry and study records

Obesity drugs in clinical development: PubMed · Curr Opin Investig Drugs, 2006 — review listing AOD-9604 as a human growth hormone fragment in obesity drug development; no DOI available
The effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism following chronic treatment in obese mice and beta(3)-AR knock-out mice: PubMed · DOI: 10.1210/endo.142.12.8522 — animal study (mice) only
Detection and in vitro metabolism of AOD9604: PubMed · DOI: 10.1002/dta.1715 — anti-doping laboratory paper; states AOD-9604 is banned by WADA and was identified in confiscated vials in the US
Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance: PubMed · DOI: 10.1007/s40279-026-02437-0 — Sports Medicine, 2026; classifies AOD-9604 among unapproved, direct-to-patient peptides

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Evidence last reviewed: September 2026. Peptide Proof reports what studies found. We do not give medical advice, dosing guidance, or treatment recommendations.