> Research Use Only (RUO) Disclaimer: This article discusses research peptides that have not been approved by the FDA or any regulatory authority for human use, diagnosis, treatment, or prevention of any medical condition. All information is provided strictly for educational and scientific research purposes. These compounds are available for laboratory research only. Not for human use, not for sale to individuals, and not intended as medical advice. Always consult a licensed healthcare provider.
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# AOD-9604 vs HGH Fragment 176-191: Which Fat-Burning Peptide Fragment for Research? 2026
If you've been researching peptides for lipolysis or fat metabolism, you've almost certainly encountered both "AOD-9604" and "HGH Fragment 176-191" as separate entries on supplier sites, forum discussions, and comparison charts. The question of which to use — or which is better — is one of the most common in research communities. The answer is surprisingly simple: they are the same peptide.
This article explains the naming confusion, the actual science of the compound, what the research shows, and what researchers should know when sourcing and working with it.
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The Short Answer: AOD-9604 = HGH Fragment 176-191
AOD-9604 and HGH Fragment 176-191 are two names for a single peptide sequence:
Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe (amino acids 177–191 of human growth hormone, with a tyrosine added at the N-terminus)
The "176-191" refers to the amino acid positions in the full-length human growth hormone (hGH) sequence. "AOD" stands for Anti-Obesity Drug, a designation coined by researchers at Monash University in Australia who developed the compound as a specific lipolytic fragment of hGH. "9604" is the development compound number from that program.
When you see both names on a supplier site or compare their molecular characteristics in any database, you will find:
- •Identical amino acid sequence
- •Identical molecular weight (~1,815 Da)
- •Identical mechanism of action
- •Identical pre-clinical research base
There is no meaningful scientific distinction between them.
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Why Do Two Names Exist?
The naming divergence has two separate origins:
1. Scientific vs. Commercial Naming
In the academic literature, the peptide is almost universally referred to as hGH fragment 176-191 or [Tyr176]hGH(176-191), reflecting its structural derivation from hGH. The scientific naming convention describes what the peptide is and where it comes from.
The name AOD-9604 emerged from the drug development program at Monash University/Metabolic Pharmaceuticals, which ran clinical trials for the compound as an obesity therapeutic between approximately 2000 and 2010. This is the regulatory and commercial name.
2. The Off-Label Research Naming Drift
After the Metabolic Pharmaceuticals program failed to secure FDA approval (see below), the compound continued to be discussed in bodybuilding and research communities. Different suppliers and forum communities adopted different names based on which literature they encountered first. Over time, both names became independently embedded in community vocabulary as though they referred to separate compounds.
They do not. The peptide is one compound with two names.
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Origin: The hGH Lipolysis Story
Human growth hormone has two distinct functional regions:
1. The anabolic domain (N-terminal) — promotes IGF-1 production, muscle protein synthesis, linear growth
2. The lipolytic domain (C-terminal, ~aa 176-191) — stimulates fat breakdown independently of IGF-1 pathways
Researchers at Monash University in the 1990s sought to isolate the fat-burning effect of hGH without its anabolic effects (which carry significant side effect profiles including fluid retention, insulin resistance, and potential tumor promotion). They identified the C-terminal fragment spanning positions 176-191 as the responsible lipolytic sequence.
The isolated fragment was shown in pre-clinical studies to:
- •Stimulate lipolysis in adipocytes
- •Not elevate IGF-1 (no anabolic effect)
- •Not cause insulin resistance
- •Retain the fat-specific effect of full-length GH
This was the scientific rationale for AOD-9604 as a weight loss drug candidate.
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Mechanism: β3-Adrenergic Receptor and Lipolysis
The mechanism of hGH Fragment 176-191 / AOD-9604 is distinct from full-length hGH. Rather than acting through the GH receptor → JAK2 → IGF-1 pathway, the fragment appears to act through:
β3-adrenergic receptor (β3-AR) activation — The β3-AR is expressed primarily in adipose tissue (brown and white fat). Its activation stimulates lipolysis (triglyceride breakdown to free fatty acids and glycerol) and, in brown adipose tissue, thermogenesis via uncoupling protein-1 (UCP-1).
Key mechanistic findings from pre-clinical studies:
- •AOD-9604 stimulates lipolysis in 3T3-L1 adipocytes at nanomolar concentrations
- •Effect is blocked by β3-AR antagonists but not by GHR antagonists — confirming independence from GH receptor signaling
- •No stimulation of IGF-1 secretion observed in rodent or cell models
- •Fat-specific lipolysis without muscle protein synthesis stimulation confirmed in rat models
Important limitation: The β3-adrenergic receptor is highly expressed in rodent adipose tissue but is expressed at much lower levels and with different pharmacology in human fat tissue. This species difference may explain why AOD-9604's impressive pre-clinical lipolysis data did not translate to meaningful weight loss in human clinical trials.
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Human Clinical Trial History
AOD-9604 entered formal clinical trials through Metabolic Pharmaceuticals:
Phase 2a trial (24 weeks, 300 µg daily subcutaneous):
- •Statistically significant weight loss vs placebo in obese subjects
- •Effect size modest (~2–3 kg excess weight loss over placebo at highest dose)
- •No adverse effects on IGF-1, glucose, or insulin
- •Published in the International Journal of Obesity (encompasses Phase 1 data; Phase 2 data references
Phase 2b trial:
- •Failed to replicate the weight loss signal at the doses and duration studied
- •The compound did not meet the pre-specified efficacy endpoints
FDA outcome: Metabolic Pharmaceuticals ultimately did not pursue NDA filing for AOD-9604 as an obesity therapeutic. The program was discontinued after Phase 2b results.
The compound has since been listed on the WADA prohibited substances list for sport, classifying it as a peptide hormone/growth factor, which paradoxically increased its community profile in bodybuilding forums despite the clinical trial failures.
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Comparison: What's the Same and What's Different?
Since AOD-9604 and HGH Fragment 176-191 are the same compound, the "comparison" is really a clarification table:
| Feature | AOD-9604 | HGH Fragment 176-191 |
|---|---|---|
| Amino acid sequence | Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe | Identical |
| Molecular weight | ~1,815 Da | Identical |
| Source | C-terminal fragment of hGH (aa 176-191) + N-terminal Tyr | Identical |
| Mechanism | β3-AR agonism → adipocyte lipolysis | Identical |
| IGF-1 stimulation | None | None |
| Anabolic effects | None documented | None documented |
| Clinical trial data | Phase 2 — modest weight loss, Phase 2b failure | Identical (same compound) |
| WADA status | Prohibited | Identical |
| Research availability | Widely available | Widely available (same compound, same suppliers) |
| Name origin | Australian drug development program (AOD = Anti-Obesity Drug) | Academic/structural naming |
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What the Research Actually Shows
For researchers approaching this compound with rigor:
What is supported by evidence:
- •Lipolysis stimulation in adipocyte cell culture (in vitro, pre-clinical)
- •β3-adrenergic receptor-mediated mechanism (pre-clinical)
- •No IGF-1 elevation in pre-clinical and clinical studies
- •No insulin resistance effects
- •Modest Phase 2a weight loss signal (human, but not replicated in Phase 2b)
What is not supported by evidence:
- •Significant, clinically meaningful fat loss in humans
- •Superior fat loss compared to other lipolytic research peptides in head-to-head studies
- •Any mechanism distinct from β3-AR agonism
The species translation problem is the central scientific limitation. Rodent adipose β3-AR pharmacology does not predict human adipose β3-AR responses well — a general limitation that has caused multiple β3-AR agonist drug programs to fail in translation.
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Sourcing and COA Considerations
When sourcing this peptide from research suppliers, both names appear. The key verification points are:
1. Sequence: Confirm amino acid sequence matches hGH(176-191) with Tyr N-terminal extension
2. Purity: HPLC ≥98%
3. Molecular weight: Mass spectrometry confirmation at ~1,815 Da
4. Disulfide bonds: The Cys residues at positions 182 and 189 (fragment numbering) can form intramolecular disulfide bonds; confirm disulfide state in COA
Use peptides.so/compare to compare AOD-9604/Fragment 176-191 prices across suppliers. Note that the same compound may be listed under either name by different suppliers — they are equivalent products assuming COA verification passes.
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Frequently Asked Questions
Q: Is AOD-9604 better than HGH Fragment 176-191?
They are the same compound. There is no "better" or "worse" — purchase based on supplier COA quality, price, and purity verification.
Q: Does this peptide build muscle?
No. The fragment lacks the N-terminal anabolic domains of full-length hGH. No IGF-1 stimulation, no anabolic signaling. It is specifically the isolated lipolytic fragment.
Q: What does the research show for human fat loss?
Clinical trials showed modest and inconsistent results. Phase 2a showed a small signal; Phase 2b did not replicate it. The compound is not approved for any therapeutic use.
Q: How does this compare to other fat-loss peptides like CJC-1295 or Tesamorelin?
CJC-1295 and Tesamorelin act as GHRH analogs, stimulating endogenous GH release which then stimulates IGF-1. They are mechanistically distinct from Fragment 176-191/AOD-9604, which bypasses GH receptor signaling entirely. Different targets, different pre-clinical profiles, different research applications.
Q: Why is it on the WADA banned list if clinical trials failed?
WADA uses a precautionary approach for peptides with growth-axis relationships. The classification reflects the compound's association with the growth hormone axis, not demonstrated human performance enhancement.
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Conclusion
AOD-9604 and HGH Fragment 176-191 are the same research peptide — the C-terminal lipolytic fragment of human growth hormone, named differently based on academic versus drug development conventions. For researchers, the key facts are: this compound stimulates lipolysis via β3-adrenergic receptor signaling in pre-clinical models; it does not elevate IGF-1 or produce anabolic effects; and its human clinical trial data showed modest, inconsistent weight loss that did not support FDA approval. Understanding the naming history prevents the common community confusion that treats them as alternatives to compare or stack.
When sourcing, verify COA with HPLC purity and mass spec identity under either name — they should resolve to the same molecular fingerprint.
> Research Use Only: This peptide is not approved for human use. All information is for educational and scientific research purposes only.
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Related resources: AOD-9604 research profile · Peptide price comparison · Fat loss peptides overview