HGH Fragment 176–191

Last Updated: August 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.

What is HGH Fragment 176–191 and how does the lipolytic mechanism work?

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.

What does the research show for HGH Fragment 176–191?

Preclinical rodent studies have reported lipolytic effects — free fatty acid mobilization and fat-mass reduction — at researched doses. The human evidence, though, does not belong to the native fragment: no human clinical trial of unmodified HGH Fragment 176–191 has been published. The clinical record that communities attach to "fragment 176–191" is actually the record of its modified analog, AOD-9604 — a separately catalogued molecule — which ran six placebo-controlled trials (~893 participants), was well tolerated, but was discontinued in 2007 after its 24-week Phase 2b obesity trial missed its primary weight-loss endpoint.1 source 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.

How does HGH Fragment 176–191 compare to GLP-1-class weight-loss peptides?

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 roughly 15–24% weight loss in published trials. The closest human benchmark for this fragment's mechanism — the AOD-9604 analog — fell below the efficacy threshold for development.

What are the documented side effects of HGH Fragment 176–191?

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.

What is the regulatory status of HGH Fragment 176–191?

HGH Fragment 176–191 is not approved for any medical indication anywhere in the world as of August 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 — a commercial/safety-status matter, not FDA drug approval or evidence of efficacy for either compound. In sport, growth-hormone fragments — including HGH Fragment 176–191 and AOD-9604 — are prohibited at all times by the World Anti-Doping Agency under Section S2.2.3 of the Prohibited List.1 source Neither the native fragment nor AOD-9604 is on the FDA's 503A list of bulk drug substances eligible for compounding, and the FDA's Pharmacy Compounding Advisory Committee voted against including AOD-9604 at its December 4, 2024 meeting.1 source Context in are peptides legal — regulatory status by country.

Why does HGH Fragment 176–191 vendor verification matter?

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).

How does Peptigrity verify HGH Fragment 176–191 vendors?

Peptigrity collects independent third-party Certificates of Analysis for HGH Fragment 176–191 from shops' official channels and verifies each for authenticity before publishing. Because shops choose which COAs to publish, results reflect the batches shops have made public rather than every production batch — a selection bias we state openly. A community-funded Testing Grant to purchase and test vials anonymously is in development. Tests in the database come from independent labs such as Janoshik Analytical, Freedom Diagnostics, and Chromate.

Frequently Asked Questions

Is HGH Fragment 176–191 actual growth hormone?

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.

Is HGH Fragment 176–191 effective for weight loss?

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.

Is HGH Fragment 176–191 legal to purchase?

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.

How can I verify an HGH Fragment 176–191 vendor is selling real product?

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.

Does Peptigrity recommend an HGH Fragment 176–191 dose?

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.

What's the difference between HGH Fragment 176–191 and AOD-9604?

They are two different, separately catalogued compounds. HGH Fragment 176–191 (CAS 66004-57-7) is the native, unmodified C-terminal fragment of growth hormone. AOD-9604 (CAS 221231-10-3) is its synthetic analog — Tyr-hGH(177–191), carrying an added N-terminal tyrosine — and it is the version that actually reached human trials, including a 24-week Phase 2b obesity study. The native fragment has no human trial program of its own, so the data and citations for the two are not interchangeable. Molecular-weight figures for the pair are reported inconsistently across sources, so sequence and CAS number — not a quoted mass — are the reliable way to tell them apart. 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.