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Fragment 176-191

HGH fragment specifically designed for fat loss

Fragment 176-191 molecular structure

Overview

HGH Fragment 176-191 is a synthetic peptide derived from the C-terminal region of human growth hormone, specifically amino acids 176-191. This fragment was developed to isolate the fat-metabolizing properties of growth hormone while eliminating effects on blood glucose, IGF-1 elevation, and cellular proliferation associated with full-length HGH. Research demonstrates the fragment stimulates lipolysis (fat breakdown) and inhibits lipogenesis (new fat formation) through mechanisms distinct from GH receptor activation. Studies show it promotes fat loss without the hyperglycemic effects of growth hormone therapy. The peptide does not compete with endogenous growth hormone for receptor binding and does not induce antibody formation. Fragment 176-191 is related to AOD9604, which adds a tyrosine residue for improved stability. Research indicates potential applications for obesity treatment with a more favorable safety profile than growth hormone therapy. The fragment requires subcutaneous injection and is typically administered in divided doses to optimize fat-burning effects.

Last reviewed: 2026-08-18

Identity & Aliases

Also known as

HGH Fragment 176-191AOD-9604 (related hGH 177-191 fragment)AOD9604hGH C-terminal lipolytic fragment
CAS221231-10-3
PubChem71300630

Full composition (formula, molecular weight, sequence) in Quick Facts →

Research Areas

Fat loss and lipolysisObesityLipid metabolism

Available Evidence

Human

The closely related compound AOD-9604 (hGH C-terminal fragment) was tested in Phase 2 obesity trials: a 12-week analysis reported greater weight loss at all doses versus placebo, with a non-linear dose response and the largest effect at 1 mg (about 0.22 kg/week vs 0.07 kg/week placebo). However, the larger Phase 2B 'OPTIONS' trial (536 enrolled, 502 randomized; oral AOD-9604 0.25/0.5/1 mg daily plus diet and exercise for 24 weeks) failed to show a significant difference in weight loss at 12 weeks, and the developer terminated the obesity program in 2007.

Animal

In-vivo studies in obese mice showed AOD-9604 suppressed weight gain without affecting lean body mass (as summarized in the FDA evaluation of the compound).

In Vitro

In-vitro studies indicate the hGH C-terminal fragment retains lipolytic activity while not binding the growth hormone receptor or stimulating growth (per literature compiled in the FDA evaluation).

Uncertain

The '176-191' fragment marketed for research is routinely conflated with AOD-9604, which itself failed its pivotal Phase 2B trial; neither has an approved indication, and fat-loss claims in humans are not supported by successful clinical programs.

Key Studies & Findings

1 studies

Benefits & Effects

4 documented

Targeted fat mobilization

anecdotalWeight Loss
View Source

No glucose/IGF-1 effects

anecdotalMetabolic
View Source

Body composition improvement

anecdotalWeight Loss
View Source

Lipolytic activity

anecdotalWeight Loss
View Source

Side Effects & Safety

2 reported

Limited human data

Unknown
View Source

Injection site reactions

mildUncommon Reversible

Onset: immediate

View Source

Limitations & Open Questions

The pivotal Phase 2B trial failed its primary endpoint and development for obesity was discontinued; human data are largely summarized in regulatory documents; the peptide is unapproved and available only as a research compound, with no established dosing or safety profile.

Pharmacology

AOD-9604 corresponds to amino acids 177-191 of human growth hormone, a C-terminal region outside the GH receptor-binding domain, designed to retain lipolytic activity without growth-promoting effects; the marketed '176-191' fragment is the 16-amino-acid C-terminal sequence. No approved dosing exists.

Reported Research Dosing

Reported values from research literature and community protocols. Educational reference only — not a dosing recommendation or medical advice.

1-2mg per day, 2-4 weeks

Half-life: 15-20 minutes

Frequently Asked Questions

Is Fragment 176-191 / AOD-9604 approved for fat loss?

No. The related AOD-9604 failed its Phase 2B obesity trial and was never approved; the fragment is sold only as an unregulated research product.

Does the fragment stimulate growth hormone?

No. It is a C-terminal hGH fragment that does not bind the growth hormone receptor and is not a GH secretagogue; its proposed effect is direct lipolysis.

Research Citations

1
Human Growth Hormone Fragment 176-191 Peptide Enhances the Toxicity of Doxorubicin-Loaded Chitosan Nanoparticles Against MCF-7 Breast Cancer Cells.

Habibullah MM, Mohan S, Syed NK, Makeen HA, Jamal QMS, Alothaid H, Bantun F, Alhazmi A, Hakamy A, Kaabi YA, Samlan G, Lohani M, Thangavel N, Al-Kasim MA (2022)

2
Hyperglycemic action of synthetic C-terminal fragments of human growth hormone.

Ng FM, Bornstein J (1978)

3
Identification of the RNA binding regions of SRP68/72 and SRP72 by systematic mutagenesis of human SRP RNA.

Yin J, Iakhiaeva E, Menichelli E, Zwieb C (2007)

4
Testicular organoids: a new model to study the testicular microenvironment in vitro?

Alves-Lopes JP, Stukenborg JB (2018)

5
The mechanism of the hyperglycaemic action of synthetic peptides related to the C-terminal sequence of human growth hormone.

Ma GY, Macaulay SL, Maggs JA, Armstrong JM, Bornstein J (1982)

Related Resources

Compare Fragment 176-191Side-by-side vs another peptidePeptide Tier ListRanked by research depthBrowse PeptidesBrowse the full peptide database

Quick Facts

Formula

C78H125N23O23S2

Molecular Weight

1.7

Sequence

YLRIVQCRSVEGSCGF

Mechanism

Modified HGH fragment specifically targeting fat metabolism without affecting blood sugar

Safety Information

Research compound only. Not approved for human use. Limited safety data available.

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