Retatrutide (LY-3298176) is a triple GIP/GLP-1/glucagon receptor agonist being developed by Eli Lilly. Phase 2 trials showed average weight loss of 24% over 48 weeks at the highest dose — exceeding both semaglutide and tirzepatide. It is not yet FDA-approved and is only available through research/compounding channels. It targets three hormonal pathways simultaneously, which appears to amplify weight loss beyond dual-agonist drugs.
How does retatrutide compare to tirzepatide?
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Retatrutide adds glucagon receptor agonism to the GIP/GLP-1 dual action of tirzepatide. Glucagon increases energy expenditure and fat oxidation, which may explain retatrutide's superior weight loss data (24% vs 22% for tirzepatide in head-to-head-comparable trials). Both cause similar GI side effects. Retatrutide is still in clinical trials; compounded versions carry higher risk than tirzepatide's established compounding market.
