What is AOD-9604?
Human growth hormone is a protein of 191 amino acids. Researchers at Monash University in Australia studied fragments from its far end, the region around amino acids 176 to 191, which seemed linked to growth hormone's effects on fat. AOD-9604 is a version of that region with a tyrosine at its start. It was developed as a possible obesity treatment by an Australian company.
The goal was to keep growth hormone's effects on fat without its effects on growth, blood sugar or IGF-1. AOD-9604 is small, just 16 amino acids, and it is not growth hormone. Researchers reported that it does not act through the growth hormone receptor the way the full hormone does. Development as an obesity drug stopped after the human results.
How does AOD-9604 work?
In fat cells and in animal studies, AOD-9604 was reported to increase lipolysis, the breakdown of stored fat, and to reduce lipogenesis, the making of new fat. In obese mice, it reduced fat gain without the changes in blood sugar or tissue growth seen with full growth hormone. Some studies reported stronger effects in obese animals than in lean ones.
Mouse studies suggested these effects may involve beta-3 adrenergic receptors, which fat cells use to respond to noradrenaline. The exact mechanism was never fully mapped. Because the human trials did not show clear effects on weight, it is unclear how well the animal findings carry over to people.
What has research looked at?
- Fat metabolism in animals
- In obese mice and rats, researchers reported less body fat gain and more fat breakdown, without effects on blood sugar or growth.
- Human weight trials
- Several placebo-controlled trials were run in adults with obesity. Smaller early trials reported modest or inconsistent effects, and a larger trial did not find a meaningful difference in weight compared with placebo.
- Human safety
- A published review of the placebo-controlled trials reported side effects similar to placebo, and found that AOD-9604 did not change IGF-1 levels or blood sugar handling.
- Cartilage and joints
- A small rabbit study in a knee osteoarthritis model reported signs of cartilage repair. This has not been tested in controlled human trials.
Overall, AOD-9604 is a case where encouraging animal results did not turn into clear benefits in human weight trials. Its short-term human safety record looks reasonable, but evidence of benefit in people is weak, and claims about fat loss or joint repair in people go beyond what the published studies show.
AOD-9604 vs HGH Fragment 176-191
The two names are often used as if they meant the same thing. Both are based on the same end region of growth hormone, and they are closely related. AOD-9604 is the specific version, with a tyrosine at its start, that went through formal development, and the human trials used AOD-9604. Online claims that one is more stable or more effective than the other are not backed by head-to-head human studies.
Side effects and cautions
In the published human trials, AOD-9604 was generally well tolerated, and reported side effects were similar to placebo. Those trials lasted weeks to months, so long-term safety is not known. Effects people describe online, such as irritation where it was injected or headaches, are anecdotal. Anyone with health questions should talk to a qualified clinician.
- Cancer history
- Human trials reported no rise in IGF-1, but it has not been studied in people with current or past cancer.
- Pregnancy and breastfeeding
- There are no safety data, so this is an unknown.
- Long-term use
- No study has followed people using AOD-9604 for years.
- Product content
- Peptides sold outside medical settings can differ from their labels, and products sold as AOD-9604 or Fragment 176-191 may be mislabeled.
Further reading
This page summarizes the research in plain words. To read the studies yourself:
- Published studies on AOD-9604 PubMed, US National Library of Medicine
- Registered human trials of AOD-9604 ClinicalTrials.gov
