Synthetic fragment of human growth hormone (amino acids 176-191), researched specifically for lipolysis and fat metabolism without GH's proliferative effects.
Last Updated: June 2026
HGH Fragment 176–191 is a synthetic 16-amino-acid C-terminal fragment of human growth hormone (residues 176 through 191), researched for lipolysis and fat metabolism without the proliferative or insulin-resistance effects associated with full-length GH. It is not approved for any medical indication and is sold as a research-use-only compound. Despite the name, it is pharmacologically distinct from intact human growth hormone — and it is also distinct from AOD-9604, a separate, catalogued analog of this fragment. Most human data attributed to "HGH Fragment 176–191" in circulation actually derives from AOD-9604, the analog that was carried into clinical trials, not from this unmodified peptide.
HGH Fragment 176–191 is a synthetic peptide corresponding to the C-terminal lipolytic domain of human growth hormone, isolated to retain GH's fat-metabolism-stimulating effect while removing the IGF-1-mediated proliferative effects and insulin antagonism. In preclinical models the fragment stimulates lipolysis in fat cells without engaging the growth hormone receptor. The catalogued analog AOD-9604 is the version that was advanced into human studies; direct human data on the unmodified fragment itself is essentially absent. Evidence level: Preclinical (rodent lipolysis); human data pertains to the AOD-9604 analog, not this compound.
Preclinical rodent studies have reported lipolytic effects — free fatty acid mobilization and fat-mass reduction — at researched doses. Human clinical evidence for the unmodified fragment is lacking: the human trial record belongs to the distinct analog AOD-9604, which reached Phase 2b for obesity in the 2000s and did not produce sufficient efficacy to continue development. Claims that present those AOD-9604 results as evidence for HGH Fragment 176–191 are extrapolations across two different molecules. Evidence level: Preclinical for this compound; human data exists only for the AOD-9604 analog.
HGH Fragment 176–191 works through direct fat-cell lipolysis rather than appetite suppression, and the available evidence points to much smaller effects than GLP-1-class compounds, whose multi-agonists produce 15%–28% weight loss in Phase 3 trials. The closest human benchmark for this fragment's mechanism — the AOD-9604 analog — fell below the efficacy threshold for development.
| Compound | Mechanism | Weight-loss effect | Clinical development |
|---|---|---|---|
| Retatrutide | GLP-1 + GIP + glucagon | 28.7% — Phase 3 | Active |
| Tirzepatide | GLP-1 + GIP (dual) | 22.5% — Phase 3 | FDA-approved |
| HGH Fragment 176–191 | Direct adipocyte lipolysis (preclinical) | No direct human data; AOD-9604 analog below threshold | Research-use only |
Direct human safety data on the unmodified fragment is limited. In trials of the related analog AOD-9604, side effects were generally mild, including injection-site reactions and occasional gastrointestinal effects. Because the fragment does not engage the GH receptor, the insulin resistance and proliferative effects of full-length GH are not expected. Long-term human safety at research-use doses is unestablished. Evidence level: Human safety data pertains to AOD-9604; long-term safety for this compound unestablished.
HGH Fragment 176–191 is not approved for any medical indication anywhere in the world as of 2026, and is sold as a research-use-only material. Its catalogued analog AOD-9604 has appeared in supplement and cosmetic contexts in some jurisdictions but likewise holds no approved therapeutic indication. Context in are peptides legal — regulatory status by country.
Because the compound is widely sold, low-cost, and straightforward to synthesize, many laboratories produce it — and quality and identity vary substantially across vendors. A specific risk for this compound: it is closely related to AOD-9604, and the two are not reliably distinguished by standard HPLC purity testing alone. Some vendors label one as the other, or mislabel other GH-derived fragments as HGH Fragment 176–191. Independent HPLC purity testing plus mass spectrometry identity confirmation are the only meaningful signals. Guidance in how to test peptides. Evidence level: Analytical (method limitation).
Peptigrity purchases HGH Fragment 176–191 vials anonymously at standard customer pricing, sends them to third-party labs for HPLC and (where available) mass spectrometry analysis, and publishes the unedited certificate of analysis. The lab test table above shows the cross-shop dataset. Methodology in how we calculate trust scores.
No. HGH Fragment 176–191 is a synthetic 16-amino-acid peptide corresponding to a small C-terminal portion of human growth hormone, not intact GH. It does not activate the GH receptor and does not produce GH-mediated effects on IGF-1, insulin sensitivity, or tissue proliferation.
Direct human efficacy data for the unmodified fragment is lacking. Its catalogued analog AOD-9604 reached Phase 2b human trials for obesity and did not show sufficient weight-loss efficacy to support development. Preclinical rodent data shows lipolytic effects, but human translation (via AOD-9604) was weak. GLP-1-class compounds produce substantially larger effects.
HGH Fragment 176–191 is legal to purchase as a research chemical for laboratory use in most jurisdictions, but it is not approved for human consumption in therapeutic contexts. Full country breakdown in the peptide legal status guide.
Look for an independent third-party HPLC certificate of analysis from a lab the vendor does not own — and for this compound, mass spectrometry identity confirmation, because it cannot be distinguished from the closely related AOD-9604 (or other GH fragments) by HPLC purity testing alone. COA interpretation in red flags in peptide certificates of analysis.
No. HGH Fragment 176–191 is not approved for human consumption, and Peptigrity is an independent review platform, not a medical authority. Anyone considering use should consult a licensed physician.
AOD-9604 is a catalogued analog of HGH Fragment 176–191 — commonly described as the tyrosine-modified ("Tyr-hGH") form — listed under a separate CAS number and PubChem record, with a molecular mass of ~1815 Da versus the fragment's ~1799 Da. Pharmacologically the two are closely related; AOD-9604 is the analog that reached Phase 2b human trials. See the dedicated AOD-9604 profile. Some vendors use the names interchangeably; the distinction matters for buyers expecting one specific molecule.
This section is for educational and informational purposes only and does not constitute medical advice. HGH Fragment 176–191 is not approved by the FDA or any other regulator for human therapeutic use. Always consult a qualified healthcare provider before using any peptide or research compound. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.
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