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.
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?
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Medically reviewed by Dr. Ana Lisa Carr, MD, MBA
Board-Certified Family Medicine Physician · Lead Provider / Medical Reviewer
NPI 1689841744 · Last reviewed: May 10, 2026
Last reviewed May 10, 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.