Peptides Studied for Weight Loss
Weight loss is the area where peptide research has produced the clearest clinical wins — and the starkest evidence gaps. Semaglutide and tirzepatide are FDA-approved, backed by tens of thousands of trial participants, and represent genuine breakthroughs in obesity medicine.
Retatrutide, Eli Lilly's investigational triple agonist (GIP/GLP-1/glucagon), is the most advanced next-generation candidate, with Phase 2 data showing up to 24.2% body weight loss and a large Phase 3 program (TRIUMPH) underway. It is not yet approved.
AOD-9604 tells a very different story. Designed as a fat-metabolism fragment of human growth hormone, it showed promise in early studies but failed its pivotal Phase IIb trial. It remains widely sold as a research compound despite that failure.
This page exists to make those differences visible. The evidence bars below each profile tell the story at a glance — but the full profiles are worth reading to understand the spectrum from FDA-approved drugs to investigational candidates to failed research compounds.
Semaglutide
GLP-1 Receptor Agonist (Ozempic, Wegovy, Rybelsus)
An FDA-approved GLP-1 receptor agonist for type 2 diabetes and weight management. One of the most extensively studied peptide drugs in history, with 25,000+ trial participants.
Tirzepatide
Dual GIP/GLP-1 Receptor Agonist (Mounjaro, Zepbound)
An FDA-approved dual GIP/GLP-1 agonist for type 2 diabetes, weight management, and sleep apnea. Head-to-head superiority over semaglutide for weight loss.
Retatrutide
Triple GIP/GLP-1/Glucagon Receptor Agonist (LY3437943)
Eli Lilly's next-generation triple agonist in Phase 3 trials. Up to 28.7% weight loss (TRIUMPH-4) and A1C reductions of up to 2.0% in T2D (TRANSCEND-T2D-1). ~1,780 participants across five trials.
AOD-9604
Advanced Obesity Drug 9604 (hGH Fragment 177-191)
A synthetic fragment of human growth hormone designed for fat metabolism. Excellent safety record across 900+ participants, but failed its pivotal Phase IIb weight loss trial.