reviewed april 2026|next review october 2026|88 physicians psi has verified|20 published studies
AOD-9604
AOD-9604 is a modified fragment of human growth hormone (amino acids 177-191 with an added N-terminal tyrosine) that reached Phase IIb clinical trials for obesity, showed statistically significant but modest fat loss (approximately 2.6 kg over 12 weeks), and was discontinued because the effect could not compete with GLP-1 agonists.
Evidence landscape: 20 published studies
20 published items. 2 human studies and 11 animal studies. One of the few research peptides with published Phase IIb clinical trial data.
- 2 Human
- 11 Animal
- 7 Reviews
Not FDA-approved. Clinical development program discontinued. Has GRAS status, meaning it is Generally Recognized as Safe for food ingredient use only. Placed on the FDA's Category 2 list (a designation that temporarily prevented licensed pharmacies from preparing this compound). It is expected to return to Category 1 (legal for pharmacy preparation) following the February 2026 HHS announcement.
Phase IIb data confirms statistically significant fat loss without affecting IGF-1, insulin, or blood glucose. The effect size (approximately 2.6 kg over 12 weeks) was not competitive with GLP-1 agonists.
One of the few research peptides with published Phase IIb clinical trial data. The fragment design successfully isolates GH lipolytic activity from growth-promoting and diabetogenic effects.
PSI Assessment
A growth hormone fragment designed to retain fat-burning properties without metabolic side effects reached Phase IIb clinical trials for obesity, showed statistically significant but modest fat loss, and was discontinued because the effect could not compete with GLP-1 agonists. AOD-9604 is one of the few research peptides with actual published human clinical trial data. That data showed a real but modest effect: approximately 2.6 kg of fat loss over 12 weeks versus placebo, without affecting IGF-1, insulin, or blood glucose.
Phase IIb data showed real but modest fat loss (2.6 kg over 12 weeks). Discontinued because the effect could not compete with GLP-1 agonists.
The mechanism is selective lipolysis through the beta-3 adrenergic pathway. AOD-9604 corresponds to amino acids 177-191 of human growth hormone with an added N-terminal tyrosine for stability. It stimulates fat breakdown and inhibits new fat formation without activating the GH receptor's growth-promoting or diabetogenic pathways. This selective fragment design is the core scientific achievement.
What the evidence supports
AOD-9604 stimulates lipolysis without raising IGF-1, insulin, or blood glucose in human studies. Phase IIb data confirms a statistically significant fat loss effect (approximately 2.6 kg over 12 weeks). The fragment design successfully retains the lipolytic activity of GH while avoiding the growth-promoting and diabetogenic properties. The safety profile from clinical trials was favorable.
What is not yet established
Whether the 2.6 kg fat loss in Phase IIb is clinically meaningful compared to current anti-obesity treatments (GLP-1 agonists produce 10-20% body weight loss). Whether AOD-9604 has meaningful cartilage repair properties in humans (animal studies only). Long-term safety beyond trial durations.
Research Evidence
The findings below cover the Phase IIb fat loss data, the program discontinuation, and the newer cartilage repair interest.
Evidence by condition
Evidence dimensions across AOD-9604 indications. Fat loss has Phase IIb confirmation with modest effect size. Cartilage repair is supported only by animal studies.
| Condition | Mechanism | Animal evidence | Human evidence | Replication |
|---|---|---|---|---|
| Fat Loss | ||||
| Cartilage/Joint Repair | ||||
| Bone Metabolism |
Phase IIb clinical trials showed statistically significant fat loss (approximately 2.6 kg versus placebo over 12 weeks) without affecting IGF-1, insulin, or blood glucose. The safety profile was favorable.
This is published human clinical trial data, which is rare for research peptides. The effect was real but modest. GLP-1 agonists (semaglutide, tirzepatide) produce 10-20% body weight loss, making the commercial calculus unfavorable.
The clinical development program was discontinued not for safety concerns but because the effect size was not competitive with emerging obesity treatments.
This distinction matters. AOD-9604 was not pulled for toxicity. The commercial calculation changed as GLP-1 agonists emerged with vastly superior efficacy.
Animal studies (animal models) suggest AOD-9604 may promote cartilage regeneration and chondrocyte survival. No controlled human trials have been published for this indication.
The cartilage repair interest is newer and supported only by animal studies. The mechanism linking a GH fragment designed for lipolysis to cartilage regeneration is not well-characterized.
2 Human|11 Animal|7 Reviews
View all 20 indexed studiesHow AOD-9604 Works
AOD-9604 enhances beta-3 adrenergic receptor-mediated lipolysis and increases hormone-sensitive lipase activity in adipocytes. It does not bind to the GH receptor with sufficient affinity to trigger JAK2 (Janus kinase 2) / STAT5 (signal transducer and activator of transcription 5) signaling, meaning it does not elevate IGF-1 or affect glucose metabolism.
AOD-9604 is like taking just the fat-burning portion of growth hormone. Researchers isolated this specific fragment to see if it could reduce body fat without affecting blood sugar or causing other growth hormone side effects. It tells fat cells to break down stored fat while blocking new fat formation.
For a more detailed view of the biology, here is what researchers have observed at the molecular level.
AOD-9604 mimics the lipolytic domain of human growth hormone (amino acids 177-191) without activating the GH receptor's growth-promoting or diabetogenic pathways. It stimulates lipolysis (fat breakdown) and inhibits lipogenesis (fat formation) in adipose tissue. The addition of a tyrosine residue at the N-terminus distinguishes it from Fragment 176-191 and was designed to improve molecular stability.
What is AOD-9604 being studied for?
Researchers are studying AOD-9604 across several health conditions. Each condition below is labeled with the strength of evidence that exists for that specific use, not for AOD-9604 overall. This means a compound can have human studies for one condition but only animal data for another.
Fat Loss
·Human TrialsPhase IIb trials showed AOD-9604 produced statistically significant fat loss compared to placebo (approximately 2.6 kg over 12 weeks). The mechanism involves stimulating lipolysis without affecting IGF-1 or insulin.
Limitations: The effect size was modest compared to current anti-obesity treatments (GLP-1 agonists produce 10-20% body weight loss). The drug development program was discontinued because the effect was not commercially competitive.
Cartilage/Joint Repair
·PreclinicalAnimal studies (animal models) suggest AOD-9604 may promote cartilage regeneration. Some clinical practitioners use it for osteoarthritis, but no controlled human trials have been published for this indication.
Limitations: No controlled human trials for cartilage repair. The mechanism linking a GH fragment designed for lipolysis to cartilage regeneration is not well-characterized.
Bone Metabolism
·PreclinicalAnimal studies show AOD-9604 may influence bone turnover markers. The clinical significance is unknown.
Limitations: Published human trials focused on fat loss, not bone endpoints. The clinical significance of the observed bone marker changes is unknown.
Safety and Regulatory Status
FDA Status: Not FDA-approved for any therapeutic indication. Has GRAS status, meaning it is Generally Recognized as Safe for food ingredient use only. Clinical development for obesity was discontinued.
Availability: Placed on the FDA's Category 2 list, meaning licensed pharmacies could not prepare it. It is expected to return to Category 1 (legal for pharmacy preparation) following the February 2026 HHS announcement, restoring the pathway for physician-prescribed use where a licensed pharmacist prepares a medicine from ingredients for an individual patient.
Class context: Modified GH fragment. Fragment 176-191 is the unmodified version that lacks published human trials. Semaglutide and tirzepatide are the FDA-approved comparators with vastly superior efficacy.
Well tolerated in clinical trials lasting up to 12 weeks. No significant adverse effects reported. Does not affect IGF-1, insulin, or blood glucose levels, which is the primary safety advantage of the fragment design.
Peptide Structure
Technical molecular data for researchers and clinicians.
Questions and Comparisons
Questions the evidence raises for a AOD-9604 discussion.
Comparison and Related Research
AOD-9604 is most often compared with other fat loss compounds. The comparisons below outline how each differs in evidence depth, mechanism, and regulatory status.
Head-to-head comparisons
Full research comparisons covering AOD-9604 and another peptide side by side.
AOD-9604 vs Semaglutide
Semaglutide is FDA-approved with extensive trials. AOD-9604 is experimental with limited data. Evidence-graded comparison for weight management research.
View full comparisonAOD-9604 vs Fragment 176-191
Both are HGH fragments targeting fat metabolism. AOD-9604 is a modified version. What the difference means, and why neither proved effective in trials.
View full comparisonRelated compounds
Frequently Asked Questions
References
Each citation links to the original study on PubMed, the U.S. National Library of Medicine database.
- 1.Study testing AOD-9604 in genetically obese mice, demonstrating that this fragment of growth hormone reduced body fat without the diabetogenic effects of full-length GH. The results suggested AOD-9604 could promote fat loss through a mechanism independent of the beta-3 adrenergic receptor.Heffernan M et al., 2001 in Endocrinology. View on PubMed
- 2.Metabolic characterization of AOD-9604 showing this synthetic peptide fragment retained the fat-burning properties of growth hormone without stimulating IGF-1 or affecting glucose metabolism. The study helped establish the rationale for developing AOD-9604 as a weight management compound.Ng FM & Sun J, 2000 in Horm Res. View on PubMed
- 3.Chronic dosing study comparing full-length growth hormone to AOD-9604 in obese mice. Both treatments increased fat oxidation and reduced body weight, but AOD-9604 did not produce the insulin resistance or IGF-1 elevation seen with full GH - supporting its more targeted metabolic profile.Heffernan MA et al., 2001 in Int J Obes Relat Metab Disord. View on PubMed
- 4.Animal study testing AOD-9604 injected into osteoarthritic rabbit joints, both alone and combined with hyaluronic acid. The results suggested potential cartilage-protective effects, representing a different therapeutic direction from the compound's original development as a weight-loss agent.Kwon DR & Park GY, 2015 in Ann Clin Lab Sci. View on PubMed
Medical Disclaimer
This content is for educational and informational purposes only and does not constitute medical advice. The information presented reflects published research as indexed by PSI and should not be used to make treatment decisions. Always consult a qualified healthcare provider before starting, stopping, or modifying any treatment.