Is AOD-9604 the same as human growth hormone?

No. AOD-9604 is a 16 amino acid fragment corresponding to positions 176-191 of the 191 amino acid HGH sequence. It is structurally much smaller than full HGH and lacks the N-terminal domains that bind the classical growth hormone receptor. As a result it does not drive IGF-1 production the way full HGH does, and it does not promote skeletal or organ growth. The two compounds are related only in that one is derived from a short stretch of the other.

Did the clinical trials show AOD-9604 works for fat loss?

The evidence is mixed. A Phase 2 injectable trial showed statistically significant fat mass reduction at 250 micrograms per day compared to placebo over 12 weeks. The larger oral Phase 2b/3 trial (METAOD006) did not meet its primary weight loss endpoint at 24 weeks. The injectable result is encouraging at small scale, but the oral trial failure is a significant setback and the compound has not been advanced for regulatory approval.

What does the GRAS notice mean for AOD-9604?

In 2014 a Generally Recognized as Safe (GRAS) notification was submitted to the FDA for AOD-9604 as a food ingredient. The FDA issued a no-objection letter for that specific use. This does not mean AOD-9604 is approved as a drug for obesity or any other condition. GRAS status applies narrowly to use as a food ingredient at defined levels and is a separate regulatory track from pharmaceutical drug approval. Marketing materials that cite GRAS status as evidence of drug safety or efficacy are misrepresenting the regulatory record.

Does AOD-9604 raise IGF-1?

Available trial data suggests it does not. Serum IGF-1 levels were measured in the injectable Phase 2 trial across multiple dose groups and remained within normal ranges throughout the study. This is consistent with the hypothesis that the fragment does not fully activate the classical GH receptor. The absence of IGF-1 elevation in a 12-week trial does not, however, constitute a comprehensive long-term safety assessment.

Is AOD-9604 approved anywhere?

No. AOD-9604 has no approved drug indication in the United States, European Union, Australia, or any other major jurisdiction. It was studied through Phase 2b/3 clinical trials but did not advance to regulatory submission. It is classified as a prescription-only substance in Australia and has no approved prescribing information elsewhere.

AOD-9604: The HGH Fragment 176-191 Research Overview

Published: May 2, 2026•Updated: May 2, 2026

Research use only. This article discusses compounds that include approved medications, investigational drugs, and research peptides. Material sold for research is not cleared for human administration and is not a substitute for medical advice.

AOD-9604 is a synthetic peptide corresponding to a short stretch of amino acids near the end of the human growth hormone sequence. Researchers developed it on the hypothesis that this fragment retained the fat-burning properties of full growth hormone while avoiding the hormone's growth-promoting and glucose-disrupting effects. This article covers what the peer-reviewed literature shows about that hypothesis, what the clinical trials found, and where the compound stands today.

What AOD-9604 is

AOD-9604 stands for Anti-Obesity Drug 9604. It is a 16 amino acid synthetic peptide that corresponds to positions 176 through 191 of the 191 amino acid human growth hormone (HGH) sequence. Because it maps to the C-terminal end of the molecule, it is also referred to in research literature as HGH fragment 176-191.

The compound was developed by researchers associated with Monash University in Melbourne, Australia and was subsequently investigated through clinical trials by the Australian biotech company Metabolic Pharmaceuticals. The central hypothesis was that this terminal fragment contained the region of HGH responsible for lipolysis (the breakdown of stored fat) while being structurally separate from the domains that drive growth and raise insulin-like growth factor 1 (IGF-1).

Structurally, AOD-9604 is sometimes formulated with an added tyrosine residue at its N-terminus to facilitate radiolabeling in research settings. The version used in most human trials omitted that addition and consisted solely of the 176-191 fragment.

The rationale for isolating the fragment

To understand why researchers isolated this particular stretch of HGH, it helps to know what full recombinant growth hormone does and why that creates a problem for obesity research.

Full HGH at pharmacological doses produces lipolysis in adipose tissue, which is why it has been used off-label in body composition contexts. But full HGH also stimulates IGF-1 production, promotes tissue and bone growth, and can cause insulin resistance at higher doses. Those effects make it a poor candidate for a chronic obesity treatment: the metabolic risk profile would likely outweigh the fat loss benefit in most patients.

Preclinical work in rodent models suggested that the fat-mobilizing activity of HGH was concentrated in the C-terminal region of the molecule. If that was correct, a fragment peptide targeting only that region might produce lipolysis without triggering the growth or metabolic side effects associated with full HGH.

•AOD-9604 does not appear to bind the classical GH receptor in the same way as full HGH, which is thought to explain why it does not drive IGF-1 production in studies to date
•The proposed mechanism involves beta-3 adrenergic receptor signaling, which activates lipolysis in adipose tissue without the same downstream insulin resistance effects
•In vitro and animal studies published in the early 2000s showed that the fragment stimulated fat cell differentiation and lipid breakdown in a dose-dependent manner
•Obese ob/ob mice treated with AOD-9604 in preclinical studies lost significantly more weight than placebo-treated controls over similar timeframes

What the clinical trials found

AOD-9604 progressed through multiple phases of human clinical testing, which is relatively unusual for a compound that ultimately did not receive regulatory approval. The trial history covers both injectable and oral formulations.

Injectable Phase 2 (early 2000s)

A Phase 2 trial published in the International Journal of Obesity tested injectable AOD-9604 at multiple doses in obese adults over 12 weeks. The group receiving 250 micrograms per day showed statistically significant fat mass reduction compared to placebo. Higher doses did not produce proportionally greater effects, and the dose response was not linear. IGF-1 levels did not rise meaningfully in any dose group, and fasting glucose was not negatively affected.

Oral formulation Phase 2b/3 (mid to late 2000s)

Metabolic Pharmaceuticals subsequently developed an oral formulation of AOD-9604 and advanced it into a large Phase 2b/3 trial designated METAOD006. Enrolling several hundred obese adults across multiple centers, the trial tested the oral compound against placebo over 24 weeks using body weight as the primary endpoint. The trial did not meet its primary endpoint: the average weight loss in the AOD-9604 arm was not statistically distinguishable from placebo at 24 weeks. Metabolic Pharmaceuticals presented subgroup analyses suggesting effects in certain patient populations, but the overall result was negative and the drug did not advance to regulatory submission.

The gap between the injectable Phase 2 results and the oral Phase 2b/3 outcome likely reflects at least two factors: oral bioavailability of peptides is typically very low without specialized delivery systems, and the 24-week, large-enrollment design of the oral trial was a more demanding test than the earlier injectable work.

IGF-1 and metabolic safety data

One of the more consistent findings across AOD-9604 studies is that the compound does not appear to elevate IGF-1. In the injectable Phase 2 work, serum IGF-1 levels remained within normal ranges across all dose groups, which supported the preclinical prediction that the fragment would not activate the full GH receptor signaling cascade.

Blood glucose and insulin sensitivity measures were similarly unaffected in the available trial data. This contrasts with full recombinant HGH, which can cause meaningful insulin resistance at the doses typically used for body composition purposes.

•No evidence of elevated IGF-1 in published Phase 2 trial data
•No adverse glucose or insulin effects observed in placebo-controlled settings
•No cases of acromegaly-related symptoms (joint swelling, carpal tunnel, enlarged hands or feet) reported in trial populations
•The most commonly reported adverse events were mild injection site reactions in the injectable trial and gastrointestinal complaints in the oral trial, both comparable in frequency to placebo groups
•Long-term safety data beyond 24 weeks is limited because no trial advanced past that duration in published literature

It is worth noting that the absence of IGF-1 elevation and metabolic disruption in trials of this size and duration does not constitute a comprehensive long-term safety profile. The largest oral trial enrolled several hundred patients but observed them for only six months, which is not sufficient to evaluate effects on tissues that respond slowly to hormonal changes.

Regulatory status and the GRAS notice

AOD-9604 does not hold an approved drug indication in the United States, European Union, Australia, or any other major regulatory jurisdiction. It was studied through Phase 2b/3 but not submitted for marketing approval after the oral trial failed its primary endpoint.

A separate regulatory pathway opened in 2014 when a Generally Recognized as Safe (GRAS) notification for AOD-9604 as a food ingredient was submitted to the FDA. The FDA responded with a no-objection letter, meaning the agency did not find evidence to dispute the GRAS determination for that specific use. This status is sometimes mischaracterized in supplement and research chemical marketing materials as a form of drug approval. It is not. GRAS applies narrowly to use as a food ingredient at specified levels and says nothing about safety or efficacy as an injectable or oral pharmaceutical.

In Australia, the Therapeutic Goods Administration (TGA) has classified AOD-9604 as a schedule 4 (prescription-only) substance. Compounding pharmacies in some jurisdictions have offered it, though regulatory scrutiny of peptide compounding has increased in recent years in both the US and Australia.

AOD-9604 in the research chemical market

Outside regulated channels, AOD-9604 is sold by research chemical vendors as a lyophilized powder for reconstitution, typically in vials labeled for laboratory research use. Products sold through these channels are not subject to pharmaceutical manufacturing standards, are not independently verified for identity or purity, and carry no prescribing information.

The compound appears in men's health and body composition forums primarily because of its proposed specificity for fat tissue, the absence of IGF-1 elevation in trials, and the perception that it is lower risk than full HGH. Those properties are real in the trial data but were not sufficient to produce clinically significant weight loss in the largest oral trial conducted. Any use of research chemical AOD-9604 falls outside medical supervision and the protections that come with regulated drug supply chains.