Metabolic · GH C-terminal fragment · Compounded 503A
HGH Fragment 176-191: the fat-loss tail of growth hormone.
HGH Fragment 176-191 is the last 16 amino acids of human growth hormone — the region responsible for GH's lipolytic effect. Isolated, it stimulates fat metabolism without raising IGF-1, affecting blood sugar, or producing the growth effects of intact GH. Often used alongside metabolic peptides for body-recomposition protocols.
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What HGH Fragment 176-191 is
HGH Fragment 176-191 (also written 'AOD' in some contexts — though AOD-9604 is a closely related modified fragment) is the C-terminal sequence of human growth hormone, amino acids 176 through 191.
It was developed by Australian researchers who showed that GH's lipolytic effect could be separated from its growth-promoting effects by isolating the C-terminal fragment — preserving fat metabolism while removing IGF-1 elevation and blood-sugar effects.
It is investigational in the U.S. and dispensed through compounded 503A pharmacies for off-label metabolic indications. Most commonly used for body-recomposition support rather than weight loss as a primary outcome.
How it works
The fragment binds and activates lipolytic pathways in adipose tissue — primarily through beta-3 adrenergic receptor signaling — without activating the GH receptor.
By not activating the GH receptor, the fragment avoids IGF-1 elevation, water retention, blood-sugar effects, and the contraindication profile of intact GH or sermorelin/tesamorelin protocols.
Net result: fat oxidation in adipose tissue rises while the metabolic and endocrine consequences of GH receptor activation are avoided. The trade-off is no lean-mass-building effect.
What patients use it for
Targeted fat metabolism
Lipolytic activity in adipose tissue without the systemic GH receptor activation that drives IGF-1, water retention, and blood-sugar effects.
No IGF-1 elevation
Suitable for patients who need fat-metabolism support but should not be on intact GH or strong GHRH protocols — including patients with relative IGF-1 concerns.
Blood-sugar neutral
Does not impair insulin sensitivity the way intact GH can — a meaningful advantage for patients with prediabetes or metabolic syndrome.
Stackable with metabolic peptides
Often used alongside semaglutide, tirzepatide, or 5-amino-1MQ in body-recomposition protocols where lean-mass support is handled separately.
Evidence summary
Heffernan M et al. (Endocrinology, 2001) demonstrated that HGH fragment 177-191 stimulates lipolysis in vivo without affecting IGF-1 or insulin sensitivity in rodent models — the foundational mechanism paper.
Ng FM et al. (Hormone & Metabolic Research, 2000) confirmed the lipolytic activity of the C-terminal fragment in adipocyte models.
Direct human RCT data is limited. The closely related modified analog AOD-9604 was studied in Phase 2 obesity trials and was generally well-tolerated, though efficacy as a standalone weight-loss drug was modest.
Honest framing: clean preclinical mechanism, real but modest human signal, useful as part of a stack rather than a standalone fat-loss drug.
Dosing and clinical context
General clinical context only. Kindr Health physicians determine the appropriate dose and protocol for each patient based on history and labs. This is not a prescription or dosing recommendation.
Most commonly subcutaneous injection. Typical regimens are once or twice daily, often timed near fasted or pre-cardio windows.
Course-based use (8–12 weeks) is more common than indefinite daily use.
Compounded HGH Fragment 176-191 from licensed 503A pharmacies is the typical U.S. dispensing pathway. Not FDA-approved.
Safety and contraindications
Generally well-tolerated in clinical experience. The main reported issues are local injection-site reactions.
Because the fragment does not activate the GH receptor, the typical GH-related concerns (water retention, joint discomfort, insulin resistance) are largely absent.
Contraindications: pregnancy, lactation, active malignancy, known hypersensitivity. Use under physician supervision.
Who it's typically considered for
- Adults wanting targeted fat-metabolism support without GH/IGF-1 elevation
- Patients on GLP-1 therapy stacking for body-recomposition rather than additional weight loss
- Patients with insulin sensitivity concerns who should not be on intact GH
- Adults using AOD-9604 looking for the closely related natural fragment
Frequently asked questions
HGH Frag 176-191 vs AOD-9604?
AOD-9604 is a modified version of the same fragment with an added tyrosine residue that extends stability. Both target the same lipolytic mechanism. AOD-9604 has more direct human clinical data.
Will HGH Frag 176-191 raise my IGF-1?
No. The defining feature is fat-metabolism activity without GH receptor activation or IGF-1 elevation.
Is it FDA-approved?
No. HGH Fragment 176-191 is investigational; compounded preparations are dispensed by licensed 503A pharmacies for off-label use.
Will it cause muscle growth?
No. The fragment has no anabolic activity at skeletal muscle — it acts only on the lipolytic mechanism of intact GH.
Can I take it with semaglutide?
Combination is common in body-recomposition protocols. The mechanisms are non-overlapping. Discuss with your physician.
How long until results?
Body-composition changes typically appear over 8–12 weeks. As a standalone fat-loss drug, the effect is modest — it works best as part of a stack with lifestyle change.
Does it affect blood sugar?
No meaningful effect on insulin sensitivity — a key contrast with intact GH or strong GHRH protocols.
Sources
- Heffernan M et al. The effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism in mice. Endocrinology (2001). — pubmed.ncbi.nlm.nih.gov/11606445
- Ng FM et al. Metabolic studies of a synthetic lipolytic domain (AOD9604) of human growth hormone. Hormone & Metabolic Research (2000). — pubmed.ncbi.nlm.nih.gov/10654535
- Stier H et al. Safety and tolerability of the hexadecapeptide AOD9604 in humans. Journal of Endocrinology and Metabolism (2013). — pubmed.ncbi.nlm.nih.gov/24379891
Considering HGH Fragment 176-191?
A Kindr Health physician reviews every longevity intake — peptides are prescribed only when medically indicated based on your history and labs. There is no charge for the initial review.
Related peptides
Medically reviewed by Kindr Health Clinical Team
Kindr Health Inc. — Editorial & Clinical Team (physician-supervised)
NPI 1609792902 · Last reviewed: July 3, 2026
Last reviewed July 3, 2026. Compounded medications are prepared by FDA-registered 503A pharmacies and are not FDA-approved drug products. Prescriptions require a clinical evaluation; a Kindr Health physician determines eligibility. Not for use in pregnancy. This page provides educational information and is not medical advice.