HGH Fragment 176-191 and AOD9604: Research Overview

HGH fragment 176-191 is a short piece of the tail end of human growth hormone. Its best-studied relative, AOD9604, is the same stretch with a tyrosine added, and it is the only version that reached human trials. In those trials it did not produce a weight-loss result that its developer judged commercially viable, and the programme was stopped in 2007. No regulator has approved either substance.

Key points

• Both substances are fragments of growth hormone (hGH). The fat-metabolism findings come from mice, rats and isolated cells, mostly from one Monash University group, and the human results were negative or unpublished. [1][2][3][4][8]
• The company behind AOD9604 ended its obesity programme on 21 February 2007 after a 536-person phase 2b trial. [8]
• We found no human trial of the unmodified 176-191 fragment. [16][17]
• Neither is approved by the FDA. A December 2024 FDA advisory committee voted 12 to 0 against putting AOD-9604 on the compounding list. WADA prohibits both. [8][9][10][14]
• In a looksmaxxing tier list that puts “HGH Frag 176-191” in C, the evidence does not back the idea that it works as a body-fat tool. [15]

What the fragment is

Human growth hormone is a 191-amino-acid protein. The fragment sold as “176-191” (also written 177-191) is the last 15 or 16 amino acids of that chain. Work on this region began in Australia: papers from Frank Ng’s group at the Department of Biochemistry, Monash University, reported in 1993 that a synthetic hGH 177-191 peptide blocked fat synthesis in rat fat tissue like the whole hormone, without a measurable fat-breakdown effect in that assay. [1] A 1994 study in obese ob/ob mice reported lower cumulative weight gain and less fat tissue after chronic treatment. [2]

AOD9604 was the follow-up. FDA describes it as a 16-amino-acid peptide, the 177-191 sequence with an extra tyrosine, and notes that it is not a component of any FDA-approved drug and has no United States Pharmacopeia monograph. [8] The names are often used interchangeably, but almost everything known in humans concerns AOD9604.

What animal and cell studies found

All of the following is non-human.

• Rats, 2000. In obese Zucker rats, a daily oral dose of AOD9604 for 19 days cut body-weight gain from 35.6 g (control) to 15.8 g. Fat tissue showed more lipolytic activity, and unlike intact hGH the peptide did not worsen insulin sensitivity in clamp tests. [3]
• Mice, 2001. In ob/ob mice treated for 14 days, both hGH and AOD9604 reduced weight gain and raised fat oxidation. AOD9604 did not raise blood sugar, did not bind the growth hormone receptor and did not drive proliferation of receptor-bearing cells. [4]
• Mice, 2001 (second paper). Both compounds raised beta-3 adrenergic receptor expression, but the long-term effect vanished in knock-out mice. FDA’s 2024 review says the molecular target is unknown. [5][8]
• Human fat tissue, 2000. A paper on a related peptide, AOD9401 (a different compound), reported lipolytic and anti-lipogenic activity in isolated human and rodent fat tissue, and slower weight gain in 10 ob/ob mice over 30 days. [6]
• Rabbit joints, 2015. In 32 rabbits with collagenase-induced knee arthritis, weekly intra-articular AOD9604 injections lowered cartilage damage scores versus saline. [7]

Rodent results are a weak guide to human body fat, and most of these come from the group that developed the compound. [3][4]

The AOD9604 clinical programme

Metabolic Pharmaceuticals, an Australian company (later a subsidiary of Calzada Ltd), ran six placebo-controlled studies in obesity, which it said involved 925 people, at Medeval in Manchester and Australian centres between 2001 and 2007. [12] FDA’s review of the published summaries lists them as follows. [8]

Study (FDA’s summary)	Size	Route and length	Result
Dose escalation	23 men with obesity	Intravenous, weekly for 4 weeks	Fatty-acid marker rose; weight change not different from placebo
Dose escalation	16 to 17 men	Oral, weekly for 4 weeks	Fatty-acid marker rose; no significant weight loss versus placebo
Dose escalation	36 men	One week	About 1 kg at one dose versus 0.6 kg placebo; no further detail
Phase 2 (abstract by Herd and colleagues, 2005)	300 adults	Oral daily, 12 weeks, five dose levels	Authors reported small differences favouring AOD9604 (for example 0.22 versus 0.07 kg per week at the lowest dose); FDA called the effect of unclear meaning; no full paper found
Phase 2b “OPTIONS”	536 enrolled, 502 randomized	Oral daily (0.25, 0.5 or 1 mg), 24 weeks, with diet and exercise	No significant difference from placebo on the primary endpoint

On 21 February 2007 the company said the phase 2b results “do not support the commercial viability” of the drug for obesity and ended development for that use. [8] FDA notes that the OPTIONS trial does not appear in the medical literature. [8] The safety paper that summarises all six studies (Stier and colleagues, 2013) was written by employees or consultants of the company that funded the trials. [8]

Osteoarthritis. In 2013 the company said AOD9604 “may have potential” in cartilage repair but that work “has only been done in preclinical studies.” [12] The rabbit study above is the published example. [7] We found no registered or published human osteoarthritis trial. ClinicalTrials.gov returned no study for “AOD9604” or “AOD-9604” when we searched on 2026-11-09, and FDA’s own 2024 search found none either. [8][16]

Unmodified 176-191 in humans. A search of Europe PMC and ClinicalTrials.gov on 2026-11-09 found no human trial of the 176-191 fragment itself. [16][17] The human data belong to AOD9604.

The GRAS claim

In June 2012 Calzada announced that AOD9604 had received a “conditional GRAS status determination by an expert scientific panel” for use in foods. Its chief executive called this “self-affirmed” status, meaning a company-commissioned finding, not an FDA decision. [11]

We searched FDA’s GRAS Notice Inventory for “AOD9604”, “AOD”, “Calzada” and “growth hormone fragment” on 2026-11-09 and each search returned no record. [13] We therefore could not verify that a GRAS notice for AOD9604 was ever filed with FDA, and there is no FDA response letter we can quote. The “USA GRAS Status” entry on a nomination form reviewed by FDA’s 2024 briefing points to the 2012 company announcement, not to an FDA letter. [8]

Regulatory status

• United States (FDA, checked 2026-11-09). Not approved; neither substance is part of any approved drug. [8] FDA’s page on bulk drug substances, current as of 22 April 2026, lists AOD-9604 among nominations that were withdrawn. It says compounded AOD-9604 may carry a significant immunogenicity risk and that FDA “identified serious adverse events that may be associated with AOD-9604, though causality is not clear.” [10] On 4 December 2024 the Pharmacy Compounding Advisory Committee voted 12 to 0 that AOD-9604 should not go on the 503A bulks list. [9]- WADA (2026 list, in force 1 January 2026). Section S2.2.3 names “growth hormone fragments, e.g. AOD-9604 and hGH 176-191.” [14] In 2013 WADA had placed AOD9604 under S0 (non-approved substances). [12]
• Australia. The company stated in April 2013 that no health authority had approved AOD9604 as a medicine. [12] FDA’s 2024 briefing reports that the Advisory Committee on Medicines Scheduling recommended adding it to the Poisons Standard among performance and image enhancing drugs, with possession without authority illegal. [8] We could not open the TGA scheduling documents, so we cannot give the schedule or decision date.
• EU, UK, Germany. Not checked in the national registers. FDA’s 2024 search of the EMA website and the European, Chinese, Indian and Japanese pharmacopoeias found no listing. [8]
• “Research use only” is a seller’s label. It is not a regulatory approval, and it does not mean a regulator reviewed purity or safety.

Risks and unknowns

• Human exposure is narrow. FDA found human data only for oral and intravenous AOD-9604. It found no data for the subcutaneous or transdermal products that sellers market, and no pharmacokinetic data. [8]
• Adverse events in the trials. Per the company’s summary, adverse events were similar to placebo and no antibodies were found in the tested subset. [8] In the 300-person 12-week study, five participants had serious events: basal cell carcinoma, squamous cell carcinoma, a lipoma, breast cancer and malignant melanoma. The investigator judged none related; FDA said there was too little detail to assess relatedness. [8] Intravenous dosing produced severe chest tightness and euphoria that were judged possibly related. [8]
• Immunogenicity and quality. FDA considers a peptide of this length able to provoke an immune response, and that impurities and aggregates in compounded or grey-market material could worsen that. [8] AOD-9604 has also turned up in seized vials and in sport. [8]
• Not studied. Long-term safety, people without obesity, pregnancy, interactions, and the unmodified 176-191 fragment in any human.

What the source post claims

@Hoostethics posted “ranking looksmaxxing techniques” on 22 October 2026. Per our transcription of the image, it places “HGH (HGH Frag 176-191)” in tier C, below the S and A tiers and above D. [15] The post gives no reasoning or evidence.

Verdict: not supported, as a body-fat tool. C reads as “modest but real.” The evidence does not show that. AOD9604 failed its main obesity trial, and the unmodified 176-191 has no human trial. If C means “minor, not worth it,” the placement is fair, but for lack of evidence rather than a measured small effect. The “HGH” label also misleads: AOD9604 does not bind the growth hormone receptor in cell tests. [4] For the full list see our tier-list evidence check.

Frequently asked questions

Is HGH fragment 176-191 the same as AOD9604? No. AOD9604 is the 177-191 stretch of growth hormone with an added tyrosine. Retail and research labels often treat them as interchangeable, but the human trials were done only with AOD9604. Our compound pages cover both: HGH fragment 176-191 and AOD-9604.

Did AOD9604 work for weight loss in humans? In the largest trial, 536 people enrolled over 24 weeks, it did not beat placebo on the primary endpoint, and the company ended the obesity programme in February 2007. Smaller earlier studies gave inconsistent or tiny differences. [8]

Is AOD9604 safe? Company-funded trials of up to 24 weeks reported few drug-related events, but the summaries are thin and FDA cites serious events of unclear cause. Long-term use and injected products are unstudied. [8][10]

Is AOD9604 banned in sport? Yes. The 2026 WADA Prohibited List names AOD-9604 and hGH 176-191 as prohibited growth hormone fragments. [14]

Sources

1. Wu Z, Ng FM, Biochem Mol Biol Int, “Antilipogenic action of synthetic C-terminal sequence 177-191 of human growth hormone” (1993). https://pubmed.ncbi.nlm.nih.gov/8358331/ (abstract read through the Europe PMC API; PubMed page blocked by a cookie notice)
2. Natera SH, Jiang WJ, Ng FM, Biochem Mol Biol Int, “Reduction of cumulative body weight gain and adipose tissue mass in obese mice: response to chronic treatment with synthetic hGH 177-191 peptide” (1994). https://pubmed.ncbi.nlm.nih.gov/7987248/ (same access)
3. Ng FM et al., Horm Res, “Metabolic studies of a synthetic lipolytic domain (AOD9604) of human growth hormone” (2000). https://pubmed.ncbi.nlm.nih.gov/11146367/ (same access)
4. Heffernan MA et al., Int J Obes Relat Metab Disord, “Increase of fat oxidation and weight loss in obese mice caused by chronic treatment with human growth hormone or a modified C-terminal fragment” (2001). https://pubmed.ncbi.nlm.nih.gov/11673763/ (same access)
5. Heffernan M et al., Endocrinology, “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” (2001). https://pubmed.ncbi.nlm.nih.gov/11713213/ (same access)
6. Heffernan MA et al., Am J Physiol Endocrinol Metab, “Effects of oral administration of a synthetic fragment of human growth hormone on lipid metabolism” (2000). https://pubmed.ncbi.nlm.nih.gov/10950816/ (same access)
7. Kwon DR, Park GY, Ann Clin Lab Sci, “Effect of Intra-articular Injection of AOD9604 with or without Hyaluronic Acid in Rabbit Osteoarthritis Model” (2015). https://pubmed.ncbi.nlm.nih.gov/26275694/ (same access)
8. FDA, Pharmacy Compounding Advisory Committee briefing document, “FDA Evaluation of AOD-9604-Related Bulk Drug Substances” (meeting 4 December 2024; memo dated 5 November 2024). https://www.fda.gov/media/183584/download
9. FDA, “Final Summary Minutes of the Pharmacy Compounding Advisory Committee Meeting” (4 December 2024). https://www.fda.gov/media/185642/download
10. FDA, “Certain bulk drug substances for use in compounding that may present significant safety risks” (current as of 22 April 2026). https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
11. Calzada Limited, ASX release “AOD9604 Receives GRAS Status” (25 June 2012). https://announcements.asx.com.au/asxpdf/20120625/pdf/4270mj9x71tv3k.pdf
12. Calzada Limited, ASX release “AOD9604 - Important Clarifications” (26 April 2013). https://announcements.asx.com.au/asxpdf/20130426/pdf/42fh15rvm7p65t.pdf
13. FDA, GRAS Notice Inventory, searches for “AOD9604”, “AOD”, “Calzada” and “growth hormone fragment” (run 2026-11-09, each 0 records). https://www.hfpappexternal.fda.gov/scripts/fdcc/index.cfm?set=GRASNotices
14. World Anti-Doping Agency, “Prohibited List 2026” (in force 1 January 2026), S2.2.3. Read from a copy hosted by the Hellenic federation: https://www.segas.gr/wp-content/uploads/2025/11/2026list_en_final_clean_september_2025.pdf
15. @Hoostethics, “ranking looksmaxxing techniques” (22 October 2026). https://x.com/Hoostethics/status/2113302148750758106 (tweet text read through the fxtwitter mirror; the tier image could not be viewed, so the tier placement comes from the project’s transcription of the image)
16. ClinicalTrials.gov API v2, searches for “AOD9604”, “AOD-9604”, “hGH 176-191”, “growth hormone fragment 176-191” (run 2026-11-09). https://clinicaltrials.gov/
17. Europe PMC REST search for 176-191 / 177-191 growth hormone fragment and AOD9604 publications (run 2026-11-09). https://europepmc.org/

This article is information, not medical advice.