AOD9604: The Growth Hormone Fragment That Burned Fat in Rats Without Insulin Side Effects

Obese Zucker rats (a standard model for metabolic obesity) received daily oral doses of AOD9604 at 500 µg/kg body weight for 19 days. Researchers measured body weight gain, fat tissue lipolytic activity, blood glucose, and insulin levels. Insulin sensitivity was assessed using euglycemic clamp techniques, comparing AOD9604-treated animals to both untreated controls and animals treated with intact human growth hormone.

Growth hormone has powerful fat-burning effects, but chronic use causes insulin resistance and other serious side effects. AOD9604 represents an attempt to isolate just the fat-burning portion of growth hormone in a smaller, safer peptide. The fact that it worked orally (most peptides are destroyed by digestion) and didn't impair insulin sensitivity made it an attractive candidate for obesity treatment. This early study launched AOD9604 into clinical development and established the rationale behind the peptide's continued popularity in compounding pharmacies.

AOD9604 became one of the most talked-about peptides in the weight loss and anti-aging communities, largely based on promising early animal data like this study. However, the story serves as a cautionary tale: despite these strong rat results, subsequent human clinical trials (Phase IIb/III) failed to demonstrate significant weight loss over placebo. The peptide is still widely sold by compounding pharmacies, but its efficacy in humans remains unproven. This 2000 study represents the scientific high point of AOD9604 research.

This is a rat study from 2000 — the obese Zucker rat model, while useful, does not fully replicate human obesity. The study was short (19 days) and measured weight gain reduction rather than established fat loss. Sample sizes typical of early preclinical work. Subsequent human clinical trials of AOD9604 failed to show significant weight loss, despite these promising animal results.