Eli Lilly's triple-agonist retatrutide produced an average 30.3% body-weight reduction at the 12 mg dose in the 2,339-participant TRIUMPH-1 obesity trial, setting a new benchmark for incretin therapy.
Eli Lilly's TRIUMPH-1 Phase 3 obesity trial, with results reported in May 2026, randomized 2,339 adults with obesity to retatrutide at 4, 9, or 12 milligrams or placebo for 104 weeks. The highest dose arm achieved an average total weight loss of about 85 pounds, representing a 30.3 percent reduction from baseline body weight. All active doses produced clinically meaningful reductions compared with placebo.
Retatrutide is a once-weekly injectable that simultaneously activates GLP-1, GIP, and glucagon receptors. The triple-receptor approach is designed to combine the appetite-suppressing effect of GLP-1 agonism, the insulin-sensitizing effect of GIP, and the energy-expenditure effect of glucagon receptor activation. If the complete TRIUMPH program sustains these results, retatrutide would overtake tirzepatide as the most effective pharmacologic weight-loss agent evaluated in Phase 3.
Follow-on trials TRIUMPH-2, TRIUMPH-3, and TRIUMPH-4 reported through mid-2026 continued to confirm substantial weight loss and improvements in A1c, triglycerides, blood pressure, and inflammatory markers in both diabetic and cardiovascular-disease populations. A regulatory filing by Eli Lilly is anticipated as the program concludes.
Source: AJMC
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