Eli Lilly's retatrutide, a triple-receptor weight loss drug targeting GLP-1, GIP, and glucagon, showed significant effectiveness in Phase 3 trials, with patients on the lowest 4-mg dose losing an average of 12.7% of body weight over 80 weeks. The drug also substantially reduced blood sugar levels and improved heart health markers, though gastrointestinal side effects and rare neurological symptoms were observed.