Retatrutide

What is Retatrutide?

Retatrutide (LY3437943) is a once-weekly injectable peptide developed by Eli Lilly and Company. It is a first-in-class triple agonist — simultaneously activating GLP-1, GIP and glucagon receptors. No other compound in pharmaceutical history has targeted all three simultaneously.

Phase 3 results are in and they've rewritten the record books. TRIUMPH-1 (May 2026, the pivotal obesity trial): 28.3% mean body weight reduction at 80 weeks at the 12mg dose — the largest weight loss ever published in a Phase 3 obesity trial, beating Tirzepatide by 5.8 percentage points and Semaglutide by 13.4. At 104 weeks in the extension cohort, up to 30.3% body weight loss was recorded. TRIUMPH-4 (December 2025): 28.7% weight loss at 68 weeks in participants with obesity and knee osteoarthritis, plus a 75.8% reduction in osteoarthritis pain.

Unlike Semaglutide (Ozempic/Wegovy) which targets only GLP-1, or Tirzepatide (Mounjaro) which adds GIP, Retatrutide's glucagon receptor activation drives energy expenditure and fat oxidation through an entirely different mechanism — which is precisely why the results are in a different category entirely.

How Retatrutide works

Retatrutide's triple receptor agonism creates a synergistic effect that goes beyond appetite suppression — it fundamentally changes how the body uses and stores energy.

Why we don't sell Ozempic

We made a deliberate choice not to stock Semaglutide or Tirzepatide. Not because we can't source them — because when you look at the data, the case for Retatrutide is clear. We only sell compounds we believe in.

Sources: Jastreboff et al. NEJM 2023 (Retatrutide Phase 2); Wilding et al. NEJM 2021 (Semaglutide STEP 1). For research purposes only.

Trial data and research summary

TRIUMPH-1 — Pivotal Phase 3 Obesity Trial (May 21, 2026): 2,339 adults with obesity or overweight with at least one weight-related comorbidity (hypertension, dyslipidemia, sleep apnea, or osteoarthritis), no diabetes. Randomised 1:1:1:1 to 4mg, 9mg, 12mg or placebo weekly for 80 weeks. Average baseline weight 248.5 lbs, BMI 40.0.

• 28.3% mean body weight reduction at 80 weeks on 12mg — the largest Phase 3 obesity result ever published
• 30.3% at 104 weeks in the extension cohort — exceeds bariatric surgery comparisons
• 45.3% of participants achieved ≥30% body weight loss at 80 weeks
• 65.3% reached BMI below 30 kg/m²
• 24.1cm mean waist circumference reduction
• Beats Tirzepatide (SURMOUNT-1) by 5.8 percentage points; Semaglutide (STEP-1) by 13.4 points

TRIUMPH-4 — Phase 3 Obesity + Knee Osteoarthritis (December 11, 2025): First Phase 3 readout of the program. 28.7% mean weight loss at 68 weeks on 12mg. Secondary findings: 75.8% reduction in osteoarthritis pain, ~20% drop in LDL cholesterol, 72% reversal rate of prediabetes to normoglycemia.

TRIUMPH program status: Two successful Phase 3 readouts. Seven additional readouts expected 2026 — TRIUMPH-2 (obesity + T2D), TRIUMPH-3 (obesity + cardiovascular disease), TRIUMPH-5 (T2D active comparator), TRIUMPH-6 (sleep apnea). FDA NDA submission estimated Q4 2026–Q1 2027. Potential approval late 2027.

Suggested research protocol

The following is based on Phase 2 trial dosing parameters. For research purposes only. Not for human consumption. Always consult a qualified healthcare professional.

Frequently asked questions

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