September 23, 2026 · 2 min read

AOD-9604: the growth hormone fragment studied for lipolytic activity

A review of preclinical research on AOD-9604, a modified fragment of human growth hormone, including its effects in obese rodents and how it is detected.

AOD-9604 is a synthetic peptide built from the C-terminal end of human growth hormone (hGH), the stretch associated with fat metabolism. The goal was to keep growth hormone's fat-burning activity and leave behind its effects on growth and insulin. The early papers are mostly in rodents, so that is what we cover.

The AOD-9604 sequence

Sequence: Tyrosine, Leucine, Arginine, Isoleucine, Valine, Glutamine, Cysteine, Arginine, Serine, Valine, Glutamic acid, Glycine, Serine, Cysteine, Glycine, Phenylalanine.

  • Polar
  • Hydrophobic
  • Positively charged
  • Negatively charged
  • Glycine or proline
Length
16 amino acids
Average mass
1,815.1 Da
Formula
C78H123N23O23S2
Tyr plus residues 177 to 191 of human growth hormone, with a disulfide bond between the two cysteines (positions 7 and 14). The mass calculated from this structure matches PubChem (CID 71300630).

Rats

A 2000 study in Hormone Research gave AOD-9604 to obese Zucker rats. Daily oral treatment for 19 days cut weight gain by more than half compared with controls, and the animals' fat tissue showed more lipolytic activity. Chronic exposure to intact growth hormone is known to hurt insulin sensitivity. In this study, AOD-9604 did not, as measured by euglycemic clamp.

Weight gain over 19 days in obese Zucker rats

  • Control35.6 g
  • AOD-9604500 micrograms per kg daily15.8 g
Mean body-weight gain with daily oral AOD-9604 versus control (Ng et al., Horm Res 2000). Values are means; grams.

Mice and the beta-3 receptor

A 2001 paper in Endocrinology reported that hGH and AOD-9604 both reduced body weight and body fat in obese mice over 14 days of treatment, and both raised expression of the beta-3 adrenergic receptor, the main lipolytic receptor in fat cells. In mice lacking that receptor, the long-term effects disappeared, but a single acute dose still increased energy expenditure and fat oxidation. The authors concluded the lipolytic action isn't mediated directly through beta-3, even though the receptor's expression goes up.

What the 2001 mouse study found

  1. 1

    14 days of treatment

    hGH or AOD-9604 given to obese mice.

  2. 2

    Wild-type mice

    Lower body weight and body fat, higher beta-3 receptor expression.

  3. 3

    Knock-out mice

    No long-term change in weight or lipolysis.

  4. 4

    Single acute dose

    Still raised energy expenditure and fat oxidation in knock-out mice.

Summary of Heffernan et al., Endocrinology 2001. Described in obese mice and beta-3 receptor knock-out mice.

Detection

Growth hormone-related compounds matter to anti-doping labs, so analytical chemists have published methods for detecting AOD-9604 and mapping its metabolism in vitro. Those papers also show mass spectrometry confirming a peptide's identity, the same principle behind the mass spec result on a certificate of analysis.

Where that leaves us

The strongest findings are from animals and cell systems. They show an effect on lipid metabolism there. They don't establish efficacy or safety in people, and we wouldn't want anyone reading them that way.

References

  1. Ng FM et al. Metabolic studies of a synthetic lipolytic domain (AOD9604) of human growth hormone. Horm Res 2000.
  2. Heffernan M et al. The effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism following chronic treatment in obese mice and beta(3)-AR knock-out mice. Endocrinology 2001.
  3. Cox HD et al. Detection and in vitro metabolism of AOD9604. Drug Test Anal 2015.

Related research notes