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Metabolic & Weight Management

HGH Fragment 176-191

Also known as Frag 176-191 · HGH Frag · lipolytic fragment

PreliminarySubcutaneous injection (reported in research contexts)Oral and intravenous administration also reported for the related AOD9604 analog in studiesNot approved by the FDA as a drug for any indication. HGH Fragment 176-191 is not lawfully marketed as a dietary supplement or medicine, and the unmodified fragment has not undergone human clinical study; material sold under this name is generally offered only as a research chemical. Its modified analog, AOD9604, was the subject of a manufacturer-submitted GRAS (Generally Recognized As Safe) notification for use as a food ingredient that the FDA accepted without questions in 2014; this GRAS food-ingredient status is distinct from drug approval, and AOD9604 is not an approved drug. Regarding pharmacy compounding, growth-hormone fragment peptides have generally fallen outside the substances FDA permits compounders to use, and the regulatory status of this class is currently in flux: in April 2026 the FDA announced the removal of 12 peptides from Category 2 of the interim Section 503A bulk drug substances list (the category for substances raising significant safety concerns that compounders may not use) and scheduled Pharmacy Compounding Advisory Committee (PCAC) review meetings beginning July 23-24, 2026. Removal from Category 2 does not by itself approve a substance, place it on the 503A bulks list, or authorize compounding; public reporting on the specific 12 peptides does not clearly establish whether AOD9604 or the unmodified fragment is among them, so the compounding status of these fragments remains unsettled. For athletes, HGH Fragment 176-191 (and AOD9604) falls under WADA Prohibited List category S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics) and is prohibited at all times, both in and out of competition.

HGH Fragment 176-191 is a synthetic peptide corresponding to the last 16 amino acids (residues 176-191) at the C-terminus of the human growth hormone molecule, the region associated in research with growth hormone's effect on fat metabolism. In preclinical models it is described as acting on adipocytes to promote lipolysis (breakdown of stored triglycerides) and to influence fatty acid oxidation, reportedly without raising IGF-1 levels or affecting insulin sensitivity the way full-length growth hormone can. Most of the human data frequently cited for this compound actually pertains to AOD9604, a structurally modified analog (a stabilized derivative with an added N-terminal tyrosine), rather than to the unmodified fragment itself; the unmodified HGH Fragment 176-191 has not been studied in humans. AOD9604 progressed through Phase I/II obesity trials that reported a favorable safety and tolerability profile but modest, ultimately unconvincing weight-loss efficacy, and development was discontinued; it was not advanced as an approved obesity drug. The overall evidence base for the fragment rests largely on animal and cell studies, with human-relevant inferences drawn indirectly from its analog.

Studied / used for

  • Studied in animal and cell models for lipolysis (breakdown of stored body fat)
  • Investigated for effects on fat metabolism and fatty acid oxidation without raising IGF-1
  • Explored (via its AOD9604 analog) as a potential obesity/weight-management candidate in early human trials
  • Examined for metabolic effects distinct from those of full-length growth hormone

Commonly reported side effects

  • Injection-site reactions commonly reported (redness, itching, or tenderness)
  • Generally reported as well tolerated in the AOD9604 analog trials, with no notable changes in IGF-1, glucose, or insulin sensitivity reported in those studies
  • Long-term safety of the unmodified fragment is unknown due to the absence of human studies
  • Unverified purity, contamination, or mislabeling risks commonly reported with unregulated research-only sourcing
Preliminary. Mostly early or animal studies. This reflects the strength of the research base, not effectiveness or a recommendation.

Not medical advice.

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