What Is HGH Fragment 176-191?
HGH Fragment 176-191 is a laboratory-produced peptide that corresponds to residues 176 through 191 of the 191-amino-acid human growth hormone molecule. The sequence is commonly represented as Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe. It was identified during research into the possibility that some of growth hormone's effects on fat metabolism reside in a region of the hormone that is separable from the structural regions responsible for growth-promoting activity. Researchers therefore investigated short growth-hormone-derived peptides as experimental tools for studying lipolysis, adipocyte biology, and energy metabolism without administering full-length growth hormone.
The principal distinction from intact human growth hormone is conceptual rather than clinically guaranteed. Full-length growth hormone binds the growth hormone receptor and can increase hepatic IGF-1 production, alter glucose tolerance, reduce insulin sensitivity, and promote sodium and water retention. Fragment 176-191 lacks the complete three-dimensional structure required for the normal endocrine actions of the intact hormone and has not been shown to reproduce the full growth-hormone/IGF-1 axis. Some preclinical studies report little or no increase in circulating IGF-1 or blood glucose after administration of related fragments; however, this should not be interpreted as proof that every preparation is metabolically neutral in humans. The often-repeated statement that Fragment 176-191 has twelve times the fat-burning potency of growth hormone comes from limited experimental comparisons and is not a validated clinical estimate.
AOD-9604 is a related, modified growth-hormone-derived peptide developed from the 176-191 region. It is frequently described in commercial material as an acetylated or otherwise chemically modified analogue, but the exact composition and manufacturing specification should be confirmed from a primary source or certificate of analysis. AOD-9604 and unmodified Fragment 176-191 are not automatically interchangeable: changes in sequence, terminal chemistry, formulation, purity, and pharmacokinetics can materially affect biological activity. Neither product is approved by major medicines regulators as a general-purpose treatment for obesity or body-composition improvement.
Quick Reference
Member reference tables summarize the compound's research parameters.
Research Indications
Research Protocols
As reported in cited literature and research-community logs (see Research Citations below), not a personal dosing recommendation.
This member section describes parameters reported in the research literature.
Peptide Interactions
This member section summarizes reported compound interactions and evidence limitations.
Reported Research Time Points
This member section summarizes reported research time points.
Safety Notes
Included for harm-reduction awareness only, in the event this compound is encountered outside its labeled research use. Inclusion here does not imply RUO Codes endorses, recommends, or instructs human use.
This member section discusses research safety considerations and uncertainties.
Quality Indicators
Research Citations
- Effects of growth hormone on glucose, lipid, and protein metabolism in human subjects.
Møller, N., Jørgensen, J. O. L., et al., 2009, Endocrine Reviews - Effects of growth hormone on lipolysis, lipid oxidation, and VLDL-triglyceride production in humans.
Djurhuus, C. B., Gravholt, C. H., et al., 2004, American Journal of Physiology-Endocrinology and Metabolism - Dose dependency of the pharmacokinetics and acute lipolytic actions of growth hormone.
Hansen, T. K., Gravholt, C. H., et al., 2002, Journal of Clinical Endocrinology & Metabolism - Growth hormone increases regional lipolysis in the fasting state.
Gravholt, C. H., Schmitz, O., et al., 2000, Journal of Clinical Endocrinology & Metabolism