Eli Lilly (LLY) : retatrutide

Eli Lilly's next-generation obesity drug, retatrutide (a triple agonist targeting GIP, GLP-1, and glucagon receptors), has shown record-breaking weight loss results in Phase 3 trials.

Key Results from Recent Trials

• TRIUMPH-4 (obesity + knee osteoarthritis, Dec 2025): In a 68-week study, the highest dose (12 mg) led to an average 28.7% body weight loss (about 71.2 lbs / 32 kg from a baseline of ~248 lbs) among those who stayed on treatment. Including dropouts, it was around 23.7%. It also significantly reduced knee pain (up to 75.8% improvement on WOMAC scores).
• TRIUMPH-1 (general obesity/overweight with comorbidities, May 2026): Highest dose achieved ~28.3% weight loss over 80 weeks. Over 45% of participants lost 30%+ of body weight, and many reached a BMI under 30. This puts it in bariatric surgery territory for many patients.
• Diabetes trial (TRANSCEND-T2D-1, Mar 2026): Strong A1C reductions (1.7–2.0%) plus up to ~16.8% weight loss (36.6 lbs) at 40 weeks, with weight loss still ongoing.

These results outperform current blockbusters like Zepbound (tirzepatide, dual GIP/GLP-1, typically ~15–22% weight loss) and Wegovy (semaglutide, ~15–20%). Retatrutide's addition of glucagon receptor agonism appears to boost fat burning and energy expenditure.Side Effects and TolerabilityGastrointestinal issues (nausea, etc.) are common, similar to other incretins, with rates up to ~42%. Discontinuation rates were notably higher than in earlier trials—some participants stopped due to perceived excessive weight loss or skin-related side effects. This is a key watchpoint for real-world use.Context and OutlookRetatrutide is part of Lilly's deep obesity pipeline (alongside the oral GLP-1 orforglipron and others like eloralintide). Regulatory filings are expected later in 2026, with potential approval/launch in 2027.These "eye-popping" results highlight rapid progress in multi-agonist drugs, but questions remain around long-term safety, muscle preservation, maintenance after stopping, and broad accessibility/cost. 

Company profile: Eli Lilly & Co. (NYSE:LLY)

Eli Lilly & Co. engages in the discovery, development, manufacture, and sale of pharmaceutical products. The firm's products consist of diabetes, oncology, immunology, neuroscience, and other products and therapies. 

• Sector: Healthcare
• Industry: Drug Manufacturers - General
• Full Time Employees: 47,000
• Founded in 1876 by Civil War veteran Col. Eli Lilly
• Headquartered in Indianapolis, Indiana
• https://www.lilly.com

Eli Lilly & Co., now the biggest US drugmaker by market cap thanks to the success of its weight-loss drugs Mounjaro and Zepbound. 

Early Eli Lilly and Company advertisement, n.d. Credit: Encyclopedia of Indianapolis Collection, Eli Lilly & Co. Archives

Lilly quickly became one of the nation’s leading pharmaceutical manufacturers, hitting $1 million in sales by 1905. The company’s success came by making fundamental transformations in production and scientific research during the 1910s and 1920s, much of which was spurred by the two grandsons of Colonel Lilly, Eli Lilly and Josiah K. Lilly Jr. The company began an aggressive plant expansion in 1909 and later pioneered the introduction of modern, systematic management methods that increased output and lowered unit costs.