HGH Fragment 176-191 vs AOD-9604: Same Peptide, Different Names?

HGH Fragment 176-191 and AOD-9604 are closely related, and in practice often the same molecule. AOD-9604 was developed as the C-terminal 177-191 sequence of human growth hormone with an added N-terminal tyrosine, which extends it to a 16-residue peptide commonly labeled "176-191." The meaningful differences are in naming, documentation, and evidence: AOD-9604 is the name used in nearly all published research and in an obesity drug-development program, while "HGH Fragment 176-191" is mostly a research-market label. Neither is an FDA-approved drug.

Educational content for licensed healthcare professionals. Not medical advice; dosing and treatment decisions belong to the prescribing clinician.

Side-by-Side Comparison

Where the Two Names Come From

Human growth hormone is a 191-amino-acid protein. In the early 1990s, researchers at Monash University showed that a synthetic peptide matching residues 177 to 191 of hGH reproduced the hormone's antilipogenic effect in rat fat tissue [7]. Chronic treatment with that 177-191 peptide later reduced weight gain and adipose mass in obese mice [8].

The same group then built an analog of the 177-191 peptide with a tyrosine added at its N-terminus. That compound was given the development code AOD9604 ("anti-obesity drug"). Its authors refer to it as a "modified C-terminal fragment" of hGH [1], and later reviews have labeled AOD9604 itself as hGH 176-191 [9].

That labeling is the source of the overlap. When a product is sold as "HGH Fragment 176-191," it is usually describing a 16-residue tyrosine-initiated peptide equivalent to AOD-9604. Some suppliers sell both names as separate products. Whether two products labeled differently contain identical molecules can only be confirmed by the certificate of analysis and the stated amino-acid sequence, not by the name.

Is There Any Real Difference?

There are three kinds of difference worth separating.

Chemical. If both products carry the same sequence, there is no chemical difference. If a product labeled "176-191" carries a different structure (for example, a different terminal modification or salt form), it is a different substance, and the AOD-9604 literature may not apply to it. Ask the pharmacy for the sequence and analytical data.

Evidentiary. The published studies, the drug-development history, and the anti-doping literature all use the AOD9604 name [1-6]. "HGH Fragment 176-191" has essentially no PubMed-indexed research under its own name. In practice, when people cite evidence for the fragment, they are citing AOD-9604 studies.

Regulatory and commercial. Two names for one molecule can mean two nomination records, two listings, or different treatment by suppliers and pharmacies. Prescribers should check the exact substance name on our FDA peptide status tracker and confirm with the compounding pharmacy which named substance it can lawfully compound.

What the Shared Evidence Shows

Because the evidence is shared, the evidence summary is the same for both names:

• Animal efficacy. In obese mice, 14 days of AOD-9604 reduced body-weight gain, increased fat oxidation, and raised plasma glycerol, comparable to intact hGH [1]. In obese Zucker rats, chronic oral administration reduced weight gain and increased lipolytic activity in fat tissue without impairing insulin sensitivity [3].
• Mechanism. AOD-9604 did not compete for the hGH receptor and did not stimulate proliferation in receptor-expressing cells [1]. It increased beta-3 adrenergic receptor expression in obese mice, and its long-term effects were lost in beta-3 receptor knockout mice [2].
• Human data. The obesity program reached phase IIa by 2002 [4], but full peer-reviewed efficacy results are not available in PubMed. There is no published randomized human efficacy trial under the "176-191" name.
• Independent assessment. A 2026 sports-medicine review groups AOD-9604 with unapproved peptides that look favorable in animal models but lack rigorous human safety data [10].

Safety Considerations for Either Name

Without adequate human trials, neither name has a well-characterized human side-effect profile. Three practical issues apply to both:

1. Product identity. Seized preparations later identified as AOD-9604 show that unlabeled or mislabeled products circulate [11]. The name on the vial is not proof of contents.
2. Animal-to-human gap. The "no effect on glucose or IGF-1" claims come from rodent and cell studies [1, 3]. They have not been demonstrated in controlled human studies.
3. Anti-doping. Detection methods exist for AOD-9604 [6]; tested athletes should check current anti-doping rules.

Regulatory Status in 2026

Neither HGH Fragment 176-191 nor AOD-9604 is FDA-approved. Neither appears as its own row on our FDA peptide status tracker, and we have not confirmed a current 503A interim category for either name, so check the tracker and the partner pharmacy before prescribing. Neither was on the July 2026 PCAC agenda or the announced agenda for the second PCAC meeting before the end of February 2027.

For the broader fat-loss landscape, including agents with randomized human data, see growth hormone peptides for fat loss, and the HGH Fragment 176-191 library page.

Frequently Asked Questions

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

Often, yes. AOD-9604 is hGH 177-191 with an added N-terminal tyrosine, which is why it is commonly called 176-191. Confirm the actual sequence on the pharmacy's certificate of analysis, because product labels are not standardized.

Which is better, AOD-9604 or Fragment 176-191?

If the sequences are identical, neither is better; they are the same molecule. AOD-9604 has the published research record and drug-development history, so evidence cited for either name is almost always AOD-9604 evidence.

Does AOD-9604 work for weight loss in humans?

It reduced weight gain in obese rodents, and it entered human obesity trials in the early 2000s, but it was not approved and full efficacy results are not available in PubMed. Effectiveness in humans has not been established in published randomized trials.

Do these fragments affect blood sugar or IGF-1?

In obese mice, AOD-9604 did not cause hyperglycemia and did not bind the growth hormone receptor, and in obese rats it did not impair insulin sensitivity. These are animal findings and have not been confirmed in controlled human studies.

Are AOD-9604 and HGH Fragment 176-191 FDA approved?

No. Neither is FDA-approved, and their 503A compounding status should be checked on our FDA peptide status tracker.

References

1. Heffernan MA, et al. Increase of fat oxidation and weight loss in obese mice caused by chronic treatment with human growth hormone or a modified C-terminal fragment. Int J Obes Relat Metab Disord. 2001;25(10):1442-9. PubMed
2. Heffernan M, 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. PubMed
3. Ng FM, et al. Metabolic studies of a synthetic lipolytic domain (AOD9604) of human growth hormone. Horm Res. 2000;53(6):274-8. PubMed
4. Wilding J. AOD-9604 Metabolic. Curr Opin Investig Drugs. 2004;5(4):436-40. PubMed
5. Kwon DR, Park GY. Effect of intra-articular injection of AOD9604 with or without hyaluronic acid in rabbit osteoarthritis model. Ann Clin Lab Sci. 2015;45(4):426-32. PubMed
6. Cox HD, et al. Detection and in vitro metabolism of AOD9604. Drug Test Anal. 2015;7(1):31-8. PubMed
7. Wu Z, Ng FM. Antilipogenic action of synthetic C-terminal sequence 177-191 of human growth hormone. Biochem Mol Biol Int. 1993;30(1):187-96. PubMed
8. Natera SH, et al. Reduction of cumulative body weight gain and adipose tissue mass in obese mice: response to chronic treatment with synthetic hGH 177-191 peptide. Biochem Mol Biol Int. 1994;33(5):1011-21. PubMed
9. Dominikowski A, et al. The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration. Front Endocrinol (Lausanne). 2026;17:1822475. PubMed
10. Mendias CL, Awan TM. Safety and efficacy of approved and unapproved peptide therapies for musculoskeletal injuries and athletic performance. Sports Med. 2026;56(8):1921-1935. PubMed
11. Vanhee C, et al. Identification and characterization of peptide drugs in unknown pharmaceutical preparations seized by the Belgian authorities: case report on AOD9604. Drug Test Anal. 2014;6(9):964-8. PubMed

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