Metabolic & Incretin Research Guide

HGH Frag 176-191: Mechanism, Handling & Research Guide

Also known as: 176-191, HGH fragment, frag 176 191, HGH Frag 176-191, lipolytic fragment, GH fragment 176-191, growth hormone fragment

Key Facts

HGH Frag 176-191 is a metabolic & incretin research peptide (C78H125N23O23S2, MW 1817.1 g/mol). HGH Fragment 176-191 is a synthetic C-terminal fragment of human growth hormone studied for lipolytic activity without the growth-promoting effects of full-length hGH. For laboratory research use only. It is supplied as a lyophilized powder for laboratory and in-vitro research use only — not for human consumption.

Classification	C-terminal human growth hormone fragment (lipolytic fragment); the optimized Tyr-modified analog is AOD9604
Molecular Formula	C78H125N23O23S2
Molecular Weight	1817.1 g/mol
CAS Number	66004-57-7
Research Half-Life	Reported short circulating half-life on the order of minutes in pharmacokinetic work on the related AOD9604 analog; precise figures vary by route and study.
Form	Lyophilized powder
Research Category	Metabolic & Incretin

What is HGH Frag 176-191?

HGH Fragment 176-191 corresponds to the final 16 amino acids of the human growth hormone molecule, a region associated with the hormone's fat-metabolizing activity. In preclinical research it has been investigated for its ability to stimulate lipolysis and inhibit lipogenesis in adipose tissue while showing little effect on IGF-1 levels, insulin sensitivity, or skeletal growth pathways. This selectivity has made it a subject of interest in metabolic and body-composition research models. Supplied as a lyophilized powder for in-vitro and laboratory research use only; not for human consumption.

HGH Frag 176-191 Research Applications

In published and preclinical research, HGH Frag 176-191 has been studied across the following areas:

Lipolysis and fat metabolism research
Body composition studies
Growth hormone fragment signaling
Metabolic research models

HGH Frag 176-191 in Research: Study Context

The published literature characterizes the C-terminal hGH region (residues 176-191), and its optimized analog AOD9604, as retaining the lipolytic (fat-mobilizing) signaling of full-length growth hormone in rodent models while not raising IGF-1 or impairing glucose tolerance; Heffernan et al. (2001) showed the lipolytic/weight effect depended on an intact beta-3 adrenergic receptor pathway in obese and beta3-AR knockout mice. Human randomized trials of AOD9604 reported a favorable safety/tolerability profile but did not demonstrate clinically meaningful metabolic-pathway research versus placebo. This material is reconstituted with bacteriostatic water to a defined mg/mL for laboratory research use only; there is no established human concentration because it is not FDA-approved. Researchers should reference the primary literature and document each lot against its Certificate of Analysis (COA).

How HGH Frag 176-191 Compares

Researchers frequently evaluate HGH Frag 176-191 alongside related compounds:

HGH Frag 176-191 vs AOD-9604 — AOD9604 is the optimized Tyr-modified version of the same hGH 176-191 lipolytic region; most cited pharmacology and human safety data come from it.
HGH Frag 176-191 vs Tesamorelin — Tesamorelin is a GHRH analog that raises endogenous GH/IGF-1, whereas the 176-191 fragment is studied specifically because it does not raise IGF-1.

HGH Frag 176-191 — Frequently Asked Questions

How does the 176-191 fragment differ mechanistically from full-length growth hormone?

Preclinical work localizes the lipolytic signaling of growth hormone to its C-terminal region (residues 176-191), which is reported not to engage the classical GH receptor growth/IGF-1 axis. In rodent studies this region affected lipid metabolism without raising IGF-1 levels, which is why it is studied as a way to separate lipolytic signaling from the growth-promoting effects of intact hGH.

What role does the beta-3 adrenergic receptor play in the published studies?

Heffernan et al. (2001) found that chronic treatment effects on body weight and lipolysis were lost in beta-3 adrenergic receptor knockout mice, indicating the chronic lipolytic response in that model required an intact beta3-AR pathway, though an acute increase in energy expenditure was still observed. This is a rodent-model mechanism, not a human clinical claim.

What is the difference between 'HGH Frag 176-191' and AOD9604?

AOD9604 is the most-studied optimized version of the 176-191 fragment, carrying an added N-terminal tyrosine on the hGH 177-191 sequence. Much of the cited pharmacology and human safety data in the literature was generated on AOD9604, so researchers comparing material should confirm the exact sequence and modification against the lot COA before treating findings as interchangeable.

What did human trials of this fragment show?

Randomized, double-blind, placebo-controlled trials of AOD9604 reported it was well tolerated without raising IGF-1 or causing insulin resistance, but the larger efficacy trials did not show statistically significant, clinically meaningful metabolic-pathway research versus placebo. It is not FDA-approved; this is research and safety literature only, not evidence of a benefit to any user.

Is HGH Frag 176-191 legal to buy for research?

HGH Frag 176-191 is sold in the United States as a research chemical for laboratory and in-vitro use only. It is not approved by the FDA for human use and is not sold for human consumption. Researchers are responsible for compliance with all applicable federal, state, and institutional regulations.

Does HGH Frag 176-191 come with a Certificate of Analysis?

Yes. Every batch of HGH Frag 176-191 from Elyte Peptides ships with a third-party Certificate of Analysis (COA) documenting identity and HPLC purity (≥98%), so research results can be traced to a verified lot.

What is HGH Frag 176-191?

HGH Fragment 176-191 is a synthetic C-terminal fragment of human growth hormone studied for lipolytic activity without the growth-promoting effects of full-length hGH. For laboratory research use only. It is supplied in 5mg vials and intended strictly for in-vitro and laboratory research use only.

How should HGH Frag 176-191 be stored?

HGH Frag 176-191 should be stored at -20°C for long-term storage or 2-8°C for short-term use. Keep the vial sealed and protected from light, moisture, and repeated freeze-thaw cycles. Once reconstituted, store at 2-8°C and use within 30 days.

What purity is HGH Frag 176-191?

HGH Frag 176-191 is manufactured to a minimum purity of ≥98% as verified by HPLC analysis, with identity confirmed by mass spectrometry. Each batch ships with a Certificate of Analysis (COA).

Research References

Heffernan M et al. 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. Endocrinology 2001;142(12):5182-9.

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