HGH Fragment 176-191
Also known as: HGH Frag, AOD-9604 precursor, Fragment 176-191, GH Frag, tyr-hGH177-191
HGH Fragment 176-191 is a modified segment of the growth hormone molecule (amino acids 176-191) that retains the fat-burning properties of GH without its growth-promoting or diabetogenic effects. It stimulates lipolysis and inhibits lipogenesis selectively.
HGH Fragment 176-191 is a 1,817.12 Da research peptide. HGH Fragment 176-191 is a modified segment of the growth hormone molecule (amino acids 176-191) that retains the fat-burning properties of GH without its growth-promoting or diabetogenic effects. It stimulates lipolysis and inhibits lipogenesis selectively.
Also called: HGH Frag, AOD-9604 precursor, Fragment 176-191
1,817.12
Molecular Weight
Daltons
2
Strong Evidence
benefits
5
Studies Cited
peer-reviewed
250-500
Typical Dose
mcg
Overview
HGH Fragment 176-191 is a synthetic peptide representing the C-terminal fragment of human growth hormone, specifically amino acids 176 through 191. Research by Ng and colleagues at Monash University identified this region of the GH molecule as the domain responsible for GH's fat-mobilizing activity. When isolated as a standalone peptide, Fragment 176-191 retains the lipolytic (fat-burning) properties of full-length GH while lacking the growth-promoting effects mediated by the GH receptor/IGF-1 axis. Crucially, this fragment does not cause hyperglycemia or insulin resistance; problems associated with full-length GH administration. The peptide stimulates lipolysis (fat breakdown) and inhibits lipogenesis (fat storage) in adipose tissue through a mechanism that is distinct from GH receptor signaling and does not involve IGF-1 elevation. HGH Fragment 176-191 was the precursor to AOD-9604, a modified version with enhanced stability that underwent extensive clinical trials. The fragment has been studied primarily for fat loss applications and represents a targeted approach to applying GH's metabolic benefits without its broader hormonal effects.
Key Takeaways: HGH Fragment 176-191
- Strongest evidence supports HGH Fragment 176-191 for no hyperglycemia and no igf-1 elevation
- Research doses typically range from 250 to 500 mcg via subcutaneous injection
- 2 benefits with strong evidence, 2 moderate, 1 preliminary
- Half-life: Approximately 30 minutes
- 5 cited research studies in this guide
Mechanism of Action
HGH Fragment 176-191 stimulates lipolysis through a mechanism that is distinct from classical GH receptor (GHR) signaling. Unlike full-length GH, which binds to GHR and activates the JAK2/STAT5 pathway leading to IGF-1 production, the fragment does not activate this pathway and does not increase IGF-1 levels. Instead, Fragment 176-191 appears to interact with a specific region on adipocyte membranes to activate hormone-sensitive lipase (HSL), the rate-limiting enzyme in triglyceride hydrolysis. This activation promotes the breakdown of stored triglycerides into free fatty acids and glycerol. Simultaneously, the fragment inhibits lipogenesis by reducing the activity of acetyl-CoA carboxylase and fatty acid synthase in adipose tissue, preventing new fat storage. The selectivity of this mechanism means Fragment 176-191 promotes fat oxidation without affecting blood glucose levels, without causing insulin resistance, and without stimulating growth of other tissues (muscle, bone, organs). Research suggests the C-terminal region of GH acts as an independent functional domain for metabolic regulation, separate from the N-terminal domain responsible for growth promotion and IGF-1 stimulation.
Research Benefits
HGH Fragment 176-191 at a Glance
HGH Fragment 176-191 stimulates lipolysis through a mechanism that is distinct from classical GH receptor (GHR) signaling.
No Hyperglycemia
Strong EvidenceUnlike full-length GH, Fragment 176-191 does not cause hyperglycemia or insulin resistance. This is a major advantage over exogenous GH for metabolic applications.
No IGF-1 Elevation
Strong EvidenceDoes not stimulate IGF-1 production, meaning it lacks the growth-promoting effects (and potential risks) of full GH while retaining fat-specific metabolic activity.
Selective Fat Loss
Moderate EvidenceStimulates lipolysis (fat breakdown) while inhibiting lipogenesis (fat formation) in adipose tissue. Preclinical studies show significant fat mass reduction without affecting lean tissue.
Anti-Lipogenic Effect
Moderate EvidenceResearch demonstrates Fragment 176-191 inhibits new fat storage by reducing key lipogenic enzyme activity, providing a dual mechanism of fat loss (increased breakdown + reduced formation).
Cartilage Regeneration
PreliminaryStudies (primarily through the AOD-9604 derivative) suggest potential for stimulating cartilage repair and proteoglycan synthesis, which could benefit joint health.
Research Dosing Protocols
Research Purposes Only: All content is for informational and research purposes only. This site does not provide medical advice, diagnosis, or treatment. Consult a qualified healthcare professional before using any peptide or supplement.
| Research Protocol | Dose Range | Route |
|---|---|---|
| Standard fat loss protocol | 250–500 mcg | Subcutaneous injection |
| Aggressive protocol | 500–1000 mcg | Subcutaneous injection |
| Weight-based research dosing | 5–8 mcg/kg | Subcutaneous injection |
Frequency
1-2 times daily
Timing
Fasted state is essential, inject 30-60 minutes before eating. Morning and/or pre-exercise are common timings.
Cycle Length
8-12 weeks typical; can be used longer given favorable safety profile
Research Notes
- 1Fasting is critical for efficacy — the fragment promotes fat oxidation, which is inhibited by insulin from food intake.
- 2Inject into subcutaneous fat in the abdomen for local and systemic lipolytic effects.
- 3Many protocols dose first thing in the morning fasted, and again before exercise.
- 4Does not affect GH levels, IGF-1, or other pituitary hormones.
- 5Fragment 176-191 does NOT build muscle or promote tissue growth, it is fat-loss-specific.
- 6AOD-9604 is a stabilized version of this fragment with more extensive clinical data.
Reconstitution Guide
Standard Reconstitution
Vial Size
5 mg
Bacteriostatic Water
2 mL
Concentration
25 mcg
per 0.1 mL (10 units)
Step-by-Step Guide
Gather Materials
HGH Fragment 176-191 vial, bacteriostatic water, alcohol swabs, insulin syringes.
Equilibrate Temperature
Remove the vial from storage and allow it to reach room temperature (5-10 minutes).
Sanitize
Swab the rubber stopper of both the peptide vial and bacteriostatic water vial with alcohol.
Draw Water
Draw 2 mL of bacteriostatic water into a syringe.
Add Water to Vial
Insert the needle into the peptide vial and direct the water stream against the glass wall — not directly onto the powder.
Mix Gently
Swirl the vial gently until the powder is fully dissolved. Never shake. The solution should be clear and colorless.
Store Properly
Refrigerate at Refrigerated (2-8°C / 36-46°F) after reconstitution. Up to 30 days refrigerated after reconstitution.
Storage Temperature
Refrigerated (2-8°C / 36-46°F) after reconstitution
Shelf Life
Up to 30 days refrigerated after reconstitution
Important Notes
- •Use bacteriostatic water for reconstitution.
- •Swirl gently; do not shake.
- •Solution should be clear and colorless.
- •Store lyophilized powder frozen (-20°C) for long-term storage.
- •Fragment peptides can be more sensitive to degradation than larger proteins.
HGH Fragment 176-191 Dosing Calculator
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HGH Fragment 176-191 Reconstitution Calculator
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Safety & Side Effects
Reported Side Effects
- !Injection site irritation (redness, minor pain; most common)
- !Mild headache (infrequent)
- !Drowsiness or fatigue (rare)
- !No hyperglycemia (confirmed in multiple studies)
- !No insulin resistance effects
- !No GH-related side effects (no water retention, no carpal tunnel, no acromegaly risk)
- !Generally well tolerated with a favorable safety profile
Potential Interactions
- ⚡Should not be combined with insulin or timed near meals — insulin inhibits lipolysis and negates the fragment's mechanism.
- ⚡Compatible with GHRPs and GHRH analogs (different mechanisms; fragment does not affect GH axis).
- ⚡No known interactions with thyroid medications.
- ⚡May be combined with other fat-loss agents, but interactions are not well characterized.
- ⚡Does not interact with the GH receptor, no competition with exogenous GH.
Important: Side effects and interactions listed here are compiled from published research and community reports. This is not a complete list. No formal drug interaction studies have been conducted for most research peptides. Always consult a qualified healthcare provider.
Research Studies
The following studies are referenced in this profile. PubMed IDs are provided where available for independent verification.
The C-terminal fragment of human growth hormone (hGH177-191) stimulates lipolysis
Key study demonstrating that the C-terminal fragment (177-191) of GH retains full lipolytic activity while lacking growth-promoting effects, establishing the concept of domain-specific GH activity.
Anti-obesity effects of hGH fragment (176-191) in obese mice
Showed Fragment 176-191 reduced body fat in obese mice by 50% over 3 weeks without affecting food intake, lean mass, or blood glucose — confirming selective fat-specific activity.
Fragment 176-191 inhibits lipogenesis and stimulates lipolysis in human adipose tissue
Demonstrated the dual mechanism of Fragment 176-191 in human adipose tissue: stimulating hormone-sensitive lipase activity (lipolysis) while reducing acetyl-CoA carboxylase activity (lipogenesis).
Metabolic effects of GH fragment without diabetogenic properties
Confirmed that Fragment 176-191 does not cause hyperglycemia or insulin resistance in animal models, distinguishing it from the metabolic complications of full-length GH administration.
The GH C-terminal fragment and cartilage regeneration
Emerging research showing the GH C-terminal fragment (and its derivative AOD-9604) may stimulate cartilage repair through proteoglycan synthesis, independent of GH/IGF-1 signaling.
Note: This is not an exhaustive list of all published research. Studies are selected for relevance and quality. Click PubMed IDs to verify sources independently. Inclusion does not imply endorsement of the peptide for any clinical use.
Frequently Asked Questions
It is a synthetic peptide consisting of amino acids 176-191 from the C-terminal end of human growth hormone. This fragment retains GH's fat-burning properties without its growth-promoting or blood sugar-raising effects.
No. Fragment 176-191 is fat-loss-specific. It does not activate the GH receptor, does not increase IGF-1, and does not promote muscle, bone, or organ growth. For muscle-building effects, full GH or GH secretagogues that raise systemic GH/IGF-1 are needed.
No. This is a key advantage. Unlike full-length GH which can cause hyperglycemia and insulin resistance, Fragment 176-191 does not affect blood glucose or insulin sensitivity. Multiple studies have confirmed this.
AOD-9604 is a modified version of Fragment 176-191 with a tyrosine residue added at the C-terminus for enhanced stability. Both share the same core mechanism, but AOD-9604 has more extensive clinical trial data and has been granted FDA GRAS (Generally Recognized as Safe) status.
Fragment 176-191 works by activating hormone-sensitive lipase to break down fat. Insulin (which rises after eating) directly inhibits this enzyme. Taking the fragment with food or near meals negates its fat-burning mechanism. Dosing fasted 30-60 minutes before meals is essential.
Yes. Since it does not affect the GH axis, it can be used alongside GH secretagogues (CJC-1295, Ipamorelin, etc.) without interference. The secretagogues provide GH-mediated benefits (muscle, recovery, sleep) while the fragment provides targeted fat loss.
Research & Educational Use Only
All content is for informational and research purposes only. This site does not provide medical advice, diagnosis, or treatment. Consult a qualified healthcare professional before using any peptide or supplement.
The information presented here is compiled from published research studies and is intended for informational purposes only. Individual results may vary. Always consult with a licensed healthcare provider.