HGH Fragment 176-191

Imagine ripping the "fat-burning" final paragraph out of a long instruction manual and selling it as a standalone product. It might do something on paper, but when someone actually built and tested a tidied-up version of just that paragraph (AOD-9604), the machine didn't lose any more weight than one running on a blank sheet.

Proposed to reproduce the lipolytic (fat-mobilising) action that resides in growth hormone's C-terminal tail while omitting the regions responsible for raising IGF-1 and impairing insulin sensitivity. Animal studies link its effects to the breakdown of stored triglycerides into free fatty acids and glycerol via hormone-sensitive lipase, alongside inhibition of new fat formation (lipogenesis). In beta3-adrenoceptor knockout mice the chronic fat-loss effect largely disappears and the compound restores suppressed beta3-AR expression; but acute energy-expenditure effects persist in those knockouts, so the original researchers concluded the lipolysis is not directly mediated by the beta3-adrenoceptor and the full mechanism remains unsettled. Typically administered by subcutaneous injection.

Research contexts. Not proven uses, and not recommendations.

The bare 176-191 fragment has no meaningful completed human efficacy trials - its reputation is built on rodent and in-vitro work. The nearest human evidence is for its modified analogue AOD-9604: roughly six trials and around 900 participants in the early 2000s established a clean safety profile, and an earlier study suggested a small weight-loss signal (about 2.6 kg vs 0.8 kg on placebo). But the pivotal 24-week Phase IIb trial (over 500 subjects) failed to show statistically significant weight loss over placebo, and clinical development was abandoned in 2007. So even the best-studied form of this idea did not work in a proper trial, and the marketed fragment is one step removed from that.

• !Sold as a "research chemical" with no UK marketing authorisation; purity, dose accuracy and sterility of grey-market vials are unverified.
• !Human efficacy is essentially unproven for the fragment itself, and the closely related analogue AOD-9604 failed its pivotal weight-loss trial.
• !The raw 176-191 peptide is chemically unstable, so what's in a vial may not match the label.
• !Marketing claims (e.g. "more potent than HGH for fat burning", large fat-loss figures) trace back to animal data and are not supported by human outcomes.
• !Long-term human safety data are absent; the FDA placed the related analogue AOD-9604 in Category 2 of its interim compounding bulks list, citing limited safety data, peptide impurities and immunogenicity concerns.
• !Injectable use carries the usual infection, contamination and unverified-product risks of self-injecting an unregulated substance.

Not a licensed medicine in the UK - the MHRA has not authorised HGH Fragment 176-191 (or AOD-9604) for any indication. It has no marketing authorisation, so it cannot legally be sold or supplied for human consumption; vials are typically traded online labelled "for research use only / not for human use" to sidestep the Human Medicines Regulations 2012. Buying it does not make it tested, safe or legal to inject. There is no NHS or NICE route to it.

• · Phase IIb· Completed - failed primary endpoint

  AOD-9604 Phase IIb obesity trial (24 weeks)

  ~500+ subjects; no statistically significant weight loss vs placebo. Development of the analogue terminated in 2007. The bare 176-191 fragment itself has no comparable trial.

1. 01
   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 — Heffernan M, Summers RJ, Thorburn A, Ogru E, Gianello R, Jiang WJ, Ng FM, Endocrinology 142(12):5182-5189 (2001)

   Key mechanistic animal study. Chronic hGH/AOD9604 fat-loss effect was absent in beta3-adrenoceptor knockout mice, but acute energy-expenditure effects persisted, so the authors concluded the lipolytic action is NOT directly beta3-AR-mediated; the compounds restore suppressed beta3-AR expression. Animal data, not human.

2. 02
   AOD9604 in obese humans - clinical (Phase II) literature on the GH fragment analogue (search) — Metabolic Pharmaceuticals / various, PubMed search (2007)

   Use this search to review the human AOD-9604 literature; the pivotal 24-week Phase IIb trial failed its weight-loss endpoint and development stopped in 2007.

3. 03
   WADA Prohibited List - S2 Peptide Hormones, Growth Factors, Related Substances and Mimetics (growth hormone fragments incl. AOD-9604 and hGH 176-191), World Anti-Doping Agency (2024)

   Confirms growth hormone fragments are banned in sport at all times.

4. 04
   FDA Pharmacy Compounding Advisory Committee briefing - AOD-9604 placed in Category 2 of the interim 503A bulks list, U.S. Food and Drug Administration (PCAC) (2024)

   Regulator cited limited safety data, peptide impurities and immunogenicity concerns for the related analogue AOD-9604.