The Definitive Peptide Research Reference Guide — Compound Review

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Retatrutide vs Mounjaro

Retatrutide vs Mounjaro (tirzepatide): triple agonist vs dual agonist. Retatrutide adds glucagon receptor agonism to the GLP-1/GIP mechanism of tirzepatide, producing greater weight loss in Phase 3 trials.

Weight Loss Comparison

Mounjaro/tirzepatide (SURMOUNT-1): 20.9% at 72 weeks. Retatrutide (TRIUMPH-1): 24.2% at 48 weeks. The additional ~3 percentage points with retatrutide is attributed to glucagon receptor agonism increasing energy expenditure.

Mechanism Difference

Mounjaro (tirzepatide): GLP-1 + GIP dual agonism. Retatrutide: GLP-1 + GIP + glucagon triple agonism. The glucagon component is the key differentiator — it increases hepatic glucose production and energy expenditure beyond what dual agonism achieves.

Regulatory Status

Mounjaro/Zepbound (tirzepatide): FDA-approved. Retatrutide: Phase 3 trials ongoing. Tirzepatide is the appropriate choice for any protocol requiring an approved compound.