Bottom line
Retatrutide is Eli Lilly's next-generation weight-loss drug — a triple agonist targeting GLP-1, GIP, and glucagon. Phase 2 showed ~24% average weight loss at 48 weeks. Filing expected 2026-2027.
What triple agonist means
- Wegovy: GLP-1 only
- Zepbound: GLP-1 + GIP
- Retatrutide: GLP-1 + GIP + glucagon
The glucagon piece adds fat oxidation and increased energy expenditure — where Zepbound turns down calorie intake, retatrutide also turns up calorie burn.
The numbers
Phase 2 TRIUMPH-1 at 48 weeks: 8.7% at 2mg, 17.1% at 4mg, 21.1% at 8mg, 24.2% at 12mg. Zepbound at 48 weeks was ~18%.
What we don't know
Long-term tolerability, maintenance dosing, launch price, cardiovascular outcomes data.
If you're on a GLP-1 today
Don't wait. Start with what's available. Retatrutide won't be broadly available until late 2026+. The weight-loss debt you accumulate waiting usually costs more than the switch difficulty later.