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PeptidesEvidence: Early clinical

AOD-9604: The Fat-Loss Fragment That Failed Its Obesity Trials

Written by
Daniel Reyes, PhD
Medically reviewed by
Dr. Sarah Lindqvist, MD
Published
June 20, 2025
Updated
June 20, 2025
Last medical review
June 20, 2025
Reviewer scope
Metabolic health
Whole foods on a dark background — AOD-9604 was designed to stimulate fat metabolism but failed its human obesity trials on efficacy

AOD-9604 is a synthetic peptide corresponding to the C-terminal "fat-burning" region of human growth hormone (amino acids 177–191), designed to stimulate lipolysis without GH’s growth and glucose effects. It advanced through human obesity trials in the 2000s, where it appeared safe but failed to produce sufficient weight loss, ending development. It is not FDA-approved; marketing it as a proven fat-loss agent contradicts its own trial history.

The elegant idea

Growth hormone burns fat but also raises IGF-1 and disturbs glucose. Isolating the lipolytic fragment promised fat metabolism without the baggage — preclinical work showed increased fat oxidation in obese rodents without growth-axis activation.

Body measurement tape, the weight-loss endpoint AOD-9604’s human obesity program could not move convincingly versus placebo

What the human program found

Across trials involving hundreds of participants, AOD-9604 was well tolerated — the safety record is genuinely decent — but weight-loss efficacy versus placebo was not commercially or clinically compelling, and the sponsor discontinued the obesity program. "Safe but insufficiently effective" is the fairest one-line summary of the evidence.

The trial dosing details live in AOD-9604 dosage research. For the compound that actually moved the weight-loss endpoint, read semaglutide explained; for the field overview, the peptide cheat sheet. Energy math comes first either way: the TDEE calculator and macro calculator.

How it is sold today vs what that record supports

  • Sold as: a proven fat-burning peptide
  • Record shows: failed efficacy endpoints in its target indication
  • Sold as: FDA-friendly (citing a food-additive GRAS filing)
  • Record shows: GRAS-for-ingestion filings are not drug approval

Frequently asked questions

What is AOD-9604?
A synthetic peptide matching the C-terminal lipolytic region of human growth hormone (amino acids 177–191), designed to stimulate fat metabolism without GH’s growth and glucose effects. It advanced through human obesity trials in the 2000s before development ended.
Does AOD-9604 work for fat loss?
Its own trial record says no: across studies involving hundreds of participants, weight loss versus placebo was not clinically or commercially compelling, and the sponsor discontinued the obesity program. "Safe but insufficiently effective" is the fairest summary.
Is AOD-9604 FDA-approved?
No. A GRAS filing for ingestion as a food ingredient is sometimes cited as FDA-friendliness, but GRAS status is not drug approval — and injectable use has essentially no published human data at all.

Questions to ask a licensed clinician

  • Given GLP-1 agonists exist with strong evidence, what role could a failed lipolytic fragment rationally play?

References

  1. Heffernan M, Summers RJ, Thorburn A, et al. (2001). The effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism. Endocrinology / metabolic research program. SourcePreclinical
  2. US Food and Drug Administration (2023). Certain bulk drug substances for use in compounding that may present significant safety risks. FDA Human Drug Compounding. SourceAgency notice
  3. Wilding JPH, Batterham RL, Calanna S, et al. (2021). Once-weekly semaglutide in adults with overweight or obesity (STEP 1). New England Journal of Medicine. SourcePhase-III RCT

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