What is hGH Fragment 176-191?
hGH 176–191 is the native 16-amino-acid sequence FLRIVQCRSVEGSCGF at the C-terminal end of human growth hormone. It represents a short segment of the hormone, rather than the complete growth-hormone protein.[3][1]
Short fragments let researchers investigate whether different parts of growth hormone have separate metabolic actions. Early experiments examined blood glucose and insulin responses; later laboratory work explored the fragment in a drug-delivery formulation.[3][1]
AOD-9604 is Tyr-hGH 177–191, with the sequence YLRIVQCRSVEGSCGF. Both sequences have 16 amino acids, but AOD-9604 starts with tyrosine where native 176–191 starts with phenylalanine. The shorter hGH 177–191 fragment is a third, distinct sequence.[9][5] For more context, read the HGH fragment and AOD-9604 comparison.
What hGH Fragment 176-191 is investigated for
hGH Fragment 176-191 evidence is grouped by practical use case and route context. Each use case separates confidence, human evidence, animal or mechanistic support, and the practical takeaway.
Glucose and insulin responses
Mixed research context
Glucose and insulin responses
Mixed research context
Metabolic effects remain preclinical; human fat-loss benefits and neutral blood-sugar effects remain unestablished.[3]
Evidence snapshot
Overall confidence
Preclinical metabolic findings provide a limited rationale. Human fat-loss benefits for native 176–191 remain unestablished.[3][1][9]
Overall confidence is a page-level composite, not an average; it weighs evidence quality, route/molecule match, and practical limitations.
Human evidence
A standalone human treatment effect remains unestablished.[3][1]
Animal / preclinical
Preclinical work concerns metabolic responses and experimental delivery systems.[1][2][3]
Mechanism support
Native hGH 176–191 can affect glucose and insulin responses in experimental models, including reduced insulin sensitivity.[3]
Forms & administration
Native hGH Fragment 176–191 has experimental peptide and nanoparticle formulations. Preparation and delivery requirements depend on the specific product.[3][1][9]
Dosing & protocols
These ranges are general reference points, not personal dosing instructions.
Typical Range
A human dose range for native 176–191 has not been established; AOD-9604 amounts describe a different molecule.[3][9]
Frequency
A repeat-dosing frequency for a standalone native-fragment product has not been established.[3][1]
Timing Considerations
Human evidence does not establish meal, exercise or bedtime anchors for native 176–191.[3][1]
Cycle Length
A human course length has not been established for the native fragment.[3][1]
Safety profile
Early native-fragment experiments raised blood glucose and reduced insulin sensitivity in rats. The size or frequency of any corresponding human risk has not been established.[3]
Regulatory status
United States
hGH Fragment 176-191 is not an FDA-approved drug name. Availability of a supplement or research preparation does not establish approval for a medical use.[8]
International
Medicinal-product authorization outside the United States remains unconfirmed for the named preparation; status depends on the exact product and country.[8]
Sports & competition
The 2026 WADA Prohibited List explicitly includes hGH 176-191 among prohibited growth-hormone fragments (S2.2.3).
How it works
Native hGH 176–191 can influence glucose and insulin responses in experimental models, including reduced insulin sensitivity. These metabolic actions differ from a demonstrated fat-loss effect.[3]
The fragment has also been explored as part of experimental drug-delivery systems. Its role within a carrier differs from the effects of the peptide taken alone.[1][3]
Research gaps & open questions
What the current literature has not yet settled about hGH Fragment 176-191:
A characterized human product and administration study are needed to establish how much native 176–191 reaches the bloodstream and how long it remains there.[1][6]
Controlled trials need to measure fat loss and glucose control together. Early rat findings raise a metabolic question; they do not establish either a human benefit or a human adverse-event rate.[3]
Head-to-head sequence comparisons would clarify which findings belong to native 176–191, shorter 177–191 or AOD-9604, preventing one molecule’s results from being assigned to another.[5][9]
Common questions
Is native hGH 176–191 the same as AOD-9604?
History & discovery
Growth-hormone fragment research sought to separate the metabolic actions of different parts of the hormone. Similar-looking tail sequences later became a recurring source of naming confusion.[3][9]
Synthetic 176–191 was among the fragments tested in normal rats. The reported findings concerned blood glucose, insulin and insulin sensitivity, rather than demonstrated human fat loss.[3]
A breast-cancer-cell study examined the fragment within a doxorubicin/chitosan system. This added formulation research, without establishing a standalone human product or administration course.[1]
10 citations
Native hGH 176–191 research focuses on glucose and insulin responses and laboratory delivery systems. Human fat-loss benefits remain unestablished, and findings for AOD-9604 concern a different sequence.[3][1][6][9][5][10]
