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Retatrutide Results: Timeline, Before & After & What to Expect (2026)

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Results Timelines

Week 24 (6 months):

  • 12 mg dose: -17.5% body weight
  • 8 mg dose: -17.3% body weight
  • 4 mg dose: -12.9% body weight

Week 48 (12 months):

  • 12 mg dose: -24.2% body weight
  • 8 mg dose: -22.8% body weight
  • 4 mg dose: -17.1% body weight

Notably, weight loss curves had not plateaued at 48 weeks, suggesting continued benefits with longer treatment duration. Preliminary topline Phase 3 data from TRIUMPH-4 at 68 weeks reported up to 28.7% weight loss with the 12 mg dose in patients with obesity and knee osteoarthritis (not a general obesity population); these results are pending full peer-reviewed publication.

Achievement thresholds at 48 weeks (12 mg dose):

  • ≥5% weight loss: 100% of participants
  • ≥10% weight loss: 93% of participants
  • ≥15% weight loss: 83% of participants
  • ≥20% weight loss: 63% of participants
  • ≥25% weight loss: 48% of participants
  • ≥30% weight loss: 26% of participants

Frequently Asked Questions

The confirmed peer-reviewed Phase 2 result is 24.2% weight loss at 48 weeks with the 12 mg dose (Jastreboff et al., NEJM 2023). Preliminary topline Phase 3 data from TRIUMPH-4 (specifically in patients with obesity and knee osteoarthritis, not a general obesity population) reported 28.7% at 68 weeks, but these results are pending full peer-reviewed publication. Individual results vary based on dose, duration, and adherence to lifestyle modifications.

Meaningful weight loss typically becomes apparent within 12 to 24 weeks. At 24 weeks, participants on the 12 mg dose had lost an average of 17.5% body weight, with continued improvements through 48 weeks and beyond.

No. Retatrutide remains investigational and is not approved by the FDA or any regulatory agency. There are 19 clinical trials underway across the TRIUMPH, TRANSCEND, and SYNERGY programs. Key Phase 3 trials (TRIUMPH-1, -2, -3) are expected to read out by Q4 2026, with NDA submission projected for Q4 2026 to Q1 2027 and a PDUFA target action date of September to October 2027. The most likely approval window is late 2027 or early 2028.

Retatrutide is administered as a once-weekly subcutaneous injection. Clinical trials used dose escalation starting at 2 to 4 mg weekly, increasing every 4 weeks to maintenance doses of 4 to 12 mg.

In cross-trial comparisons (not head-to-head studies), retatrutide has demonstrated greater weight loss than both: semaglutide 2.4 mg (Wegovy) produced approximately 15% weight loss in STEP 1, tirzepatide 15 mg (Zepbound) produced approximately 22.5% in SURMOUNT-1, and retatrutide 12 mg produced 24.2% in Phase 2 (48 weeks) and up to 28.7% in preliminary Phase 3 data (68 weeks). The key difference is retatrutide's additional glucagon receptor agonism, which increases energy expenditure and fat oxidation.

As of March 2026, two Phase 3 trials have reported topline results. TRIUMPH-4 (December 2025) showed 28.7% weight loss at 68 weeks in patients with obesity and knee osteoarthritis. TRANSCEND-T2D-1 (March 2026) showed HbA1c reductions of -1.7% to -2.0% and weight loss of 11.5% to 16.8% in 537 patients with type 2 diabetes over 40 weeks. Additional Phase 3 readouts from TRIUMPH-1, -2, and -3 are expected through Q4 2026.

This content is for educational and informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making any health-related decisions.

References

  1. Jastreboff AM, et al. Triple–Hormone-Receptor Agonist Retatrutide for Obesity, A Phase 2 Trial. N Engl J Med. 2023;389:514-526.
  2. Rosenstock J, et al. Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial. Lancet. 2023;402(10401):529-544.
  3. Eli Lilly. What to know about retatrutide.
  4. Lilly's triple G agonist boasts 28.7% weight loss in Phase III trial. Clinical Trials Arena. 2025.
  5. Lilly's obesity triple pulls off 29% weight loss in trial. Pharmaphorum. 2025.
  6. Effects of retatrutide on body composition in people with type 2 diabetes. Lancet Diabetes Endocrinol. 2025.
  7. Efficacy and safety of retatrutide, a novel GLP-1, GIP, and glucagon receptor agonist. PMC. 2024.
  8. Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatohepatitis. Nature Medicine. 2024.
  9. The power of three: Retatrutide's role in modern obesity management. European Journal of Pharmacology. 2024.
  10. Retatrutide for Weight Loss: Availability, Dosage, and More. GoodRx. 2025.
  11. Eli Lilly. Lilly's retatrutide demonstrates significant improvements in blood sugar control and weight loss in adults with type 2 diabetes (TRANSCEND-T2D-1). Press release, March 2026.
  12. Marathe CS, et al. Retatrutide suppresses tumor growth in preclinical models of pancreatic and lung cancer. npj Metabolic Health and Disease. 2025.
  13. Retatrutide — A Game Changer in Obesity Pharmacotherapy: A Comprehensive Review. Biomolecules. 2025.
  14. Eli Lilly. Lilly's triple agonist retatrutide delivered weight loss averaging 28.7% in Phase 3 TRIUMPH-4 trial. Press release, December 2025.
  15. WADA Prohibited List 2026. World Anti-Doping Agency.
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