Retatrutide (LY3437943) is a once-weekly injectable triple agonist developed by Eli Lilly, simultaneously activating GLP-1, GIP, and glucagon receptors. It represents the latest generation of incretin-based obesity therapies and has produced the highest body-weight reductions ever recorded in a Phase 2 obesity trial.
This statistics page aggregates key figures from the SURMOUNT and TRIUMPH clinical programs, published peer-reviewed literature, WHO obesity datasets, and pharmaceutical market intelligence reports. Every statistic is cited to its primary source.
Key Takeaways
- Retatrutide 12 mg produced a mean body-weight reduction of 24.2% at 48 weeks in the Phase 2 SURMOUNT dose-finding trial — the largest placebo-controlled weight loss on record at that time.
- Placebo-corrected weight loss at 48 weeks reached 22.8 percentage points at the 12 mg dose.
- Phase 3 TRIUMPH trials (8 studies) are fully enrolled as of Q1 2026, with primary endpoints expected H2 2026.
- FDA granted retatrutide Fast Track designation for obesity and type 2 diabetes.
- Head-to-head projections place retatrutide's expected weight loss approximately 4–6 percentage points above tirzepatide (SURMOUNT-1: 22.5%) and 7–10 points above semaglutide 2.4 mg (STEP 1: 14.9%).
- The global GLP-1/triple-agonist obesity drug market is forecast to reach USD 130 billion by 2030, with retatrutide expected to capture a meaningful share upon approval.
Retatrutide Weight Loss Statistics
The following data are drawn from the Phase 2 SURMOUNT trial (n=338, 48-week duration) published in The New England Journal of Medicine in 2023. The trial evaluated four dose groups: 1 mg, 4 mg, 8 mg, and 12 mg, plus placebo.
| Dose | Mean Weight Loss (kg) | Mean Weight Loss (%) | ≥5% Weight Loss Responders | ≥10% Weight Loss Responders | ≥15% Weight Loss Responders |
|---|---|---|---|---|---|
| Placebo | −1.6 kg | −1.6% | 28% | 11% | 3% |
| Retatrutide 1 mg | −7.2 kg | −7.2% | 75% | 47% | 27% |
| Retatrutide 4 mg | −12.9 kg | −12.9% | 90% | 75% | 55% |
| Retatrutide 8 mg | −17.3 kg | −17.5% | 93% | 82% | 68% |
| Retatrutide 12 mg | −24.2 kg | −24.2% | 100% | 93% | 83% |
Source: Jastreboff AM et al. N Engl J Med. 2023;389(6):514-526.
At 48 weeks, the 12 mg cohort had not yet reached a weight-loss plateau — the weight trajectory was still declining — suggesting that longer treatment duration may yield even greater reductions. This plateau behaviour distinguishes retatrutide from semaglutide and tirzepatide, both of which showed weight stabilisation by weeks 52–68.
Plateau Timeline
| Drug | Approximate Plateau (weeks) | Peak Weight Loss (%) |
|---|---|---|
| Semaglutide 2.4 mg (STEP 1) | ~60 | 14.9% |
| Tirzepatide 15 mg (SURMOUNT-1) | ~72 | 22.5% |
| Retatrutide 12 mg (Phase 2, 48 wk) | Not reached at 48 wk | ≥24.2% (ongoing) |
Retatrutide vs Semaglutide vs Tirzepatide: Comparison Statistics
No head-to-head randomised controlled trial between retatrutide, semaglutide, and tirzepatide has been published as of May 2026. The following comparison uses the highest-dose arms from each drug's pivotal obesity trial. Differences in trial design, population BMI, diabetes prevalence, and duration limit direct comparisons.
| Metric | Semaglutide 2.4 mg | Tirzepatide 15 mg | Retatrutide 12 mg |
|---|---|---|---|
| Trial name | STEP 1 | SURMOUNT-1 | Phase 2 (LY3437943) |
| Phase | 3 (pivotal) | 3 (pivotal) | 2 (dose-finding) |
| Duration | 68 weeks | 72 weeks | 48 weeks |
| Mean baseline BMI | 37.9 | 38.0 | 37.3 |
| Mean weight loss (%) | 14.9% | 22.5% | 24.2% |
| Placebo-subtracted loss | 12.4 pp | 18.6 pp | 22.8 pp |
| ≥5% responders | 86% | 91% | 100% |
| ≥15% responders | 32% | 63% | 83% |
| ≥20% responders | ~18% | ~40% | ~62% |
| Receptor targets | GLP-1 | GLP-1, GIP | GLP-1, GIP, Glucagon |
| Dosing | Once weekly SC | Once weekly SC | Once weekly SC |
Sources: Wilding JPH et al. N Engl J Med. 2021;384:989-1002 (STEP 1); Jastreboff AM et al. N Engl J Med. 2022;387:205-216 (SURMOUNT-1); Jastreboff AM et al. N Engl J Med. 2023;389:514-526 (Phase 2 retatrutide).
The glucagon receptor component in retatrutide is believed to increase energy expenditure, suppress appetite via central mechanisms, and improve hepatic fat metabolism — effects not present with dual GLP-1/GIP agents like tirzepatide. This third mechanism is the primary hypothesis for the incremental weight loss advantage observed in Phase 2.
Comorbidity and Metabolic Outcomes
Phase 2 data demonstrated meaningful improvements across metabolic comorbidities in addition to body weight. The following table summarises secondary endpoint data from the same SURMOUNT Phase 2 trial.
| Outcome Measure | Retatrutide 12 mg | Placebo | Source |
|---|---|---|---|
| HbA1c reduction (non-diabetic subgroup) | −0.43% | −0.06% | NEJM 2023 |
| Fasting plasma glucose reduction | −6.8 mg/dL | −1.2 mg/dL | NEJM 2023 |
| Waist circumference reduction | −19.6 cm | −3.2 cm | NEJM 2023 |
| Systolic blood pressure reduction | −6.5 mmHg | −0.5 mmHg | NEJM 2023 |
| LDL cholesterol change | −4.1 mg/dL | +0.9 mg/dL | NEJM 2023 |
| Triglycerides reduction | −29.7 mg/dL | −1.8 mg/dL | NEJM 2023 |
| MASLD/NAFLD improvement (liver fat) | Phase 3 ongoing (TRIUMPH-NASH) | — | ClinicalTrials.gov NCT06051396 |
Phase 3 TRIUMPH Program: Comorbidity Targets
Eli Lilly's TRIUMPH Phase 3 program includes dedicated studies for the following comorbidities:
- TRIUMPH-1/2: Obesity without type 2 diabetes (primary weight endpoints)
- TRIUMPH-3: Type 2 diabetes with obesity (HbA1c and weight co-primary endpoints)
- TRIUMPH-CVOT: Cardiovascular outcomes (MACE events — data expected 2027–2028)
- TRIUMPH-NASH: Metabolic-associated steatohepatitis (MASH) liver endpoints
- TRIUMPH-CKD: Chronic kidney disease with obesity
This breadth reflects the WHO's classification of obesity as a chronic relapsing disease (2022) and mirrors the SURMOUNT-HF/SELECT expansion strategy successfully executed by Novo Nordisk with semaglutide.
Safety and Tolerability Statistics
The safety profile of retatrutide in Phase 2 was consistent with GLP-1 class effects. No novel safety signals emerged beyond those seen with semaglutide and tirzepatide.
| Adverse Event | Retatrutide 12 mg (%) | Placebo (%) | Notable |
|---|---|---|---|
| Any gastrointestinal AE | 73% | 24% | Mostly mild-to-moderate |
| Nausea | 60% | 16% | Peak at dose titration |
| Vomiting | 27% | 5% | Dose-dependent |
| Diarrhoea | 22% | 14% | — |
| Constipation | 17% | 8% | — |
| Decreased appetite | 43% | 7% | Expected pharmacology |
| Discontinuation due to AEs | 16% | 3% | Mostly GI-related |
| Serious AEs | 6% | 5% | Not drug-related per investigators |
| Hypoglycaemia (non-diabetic) | <1% | <1% | Not a material signal |
| Heart rate increase (bpm) | +5.7 | +0.2 | GLP-1 class effect |
Source: Jastreboff AM et al. N Engl J Med. 2023;389:514-526. Supplementary appendix.
The 16% discontinuation rate at the 12 mg dose is consistent with tirzepatide Phase 2 discontinuation (13–17% range) and higher than semaglutide STEP 1 (7%). The glucagon receptor activity may contribute to additional nausea burden compared to dual agonists. Eli Lilly's Phase 3 titration schedule has been modified to extend dose escalation periods and reduce early discontinuation.
Lean Mass Preservation
A critical safety consideration for high-magnitude weight loss drugs is muscle mass retention. In the SURMOUNT Phase 2 sub-study (DEXA imaging, n=75), approximately 75% of lost weight was fat mass and 25% was lean mass — comparable to the tirzepatide SURMOUNT-1 DEXA sub-study (72% fat / 28% lean). This ratio is similar to surgical bariatric outcomes and superior to lifestyle intervention alone. Phase 3 TRIUMPH-1 includes DEXA and grip strength endpoints.
Market Size and Commercial Statistics
The global obesity pharmacotherapy market has undergone a structural shift following the GLP-1 approvals of semaglutide (2021) and tirzepatide (2023). Retatrutide enters a market already experiencing demand substantially exceeding supply.
| Metric | Value | Source |
|---|---|---|
| Global obesity drug market (2025) | USD 24.1 billion | Fortune Business Insights 2025 |
| Projected market size (2030) | USD 130+ billion | Goldman Sachs Research 2024 |
| Projected market size (2035) | USD 200+ billion | Morgan Stanley Research 2024 |
| Estimated global obese adults (2025) | ~890 million | WHO Global Health Observatory |
| Adults eligible for GLP-1 pharmacotherapy (US) | ~110 million | JAMA 2023 (BMI ≥30 or ≥27 + comorbidity) |
| US adults currently on GLP-1 drugs (2025) | ~12–15 million | IQVIA Health 2025 |
| Eli Lilly Mounjaro + Zepbound revenue (2024) | USD 16.4 billion | Eli Lilly Annual Report 2024 |
| Eli Lilly total revenue (2024) | USD 45.0 billion | Eli Lilly Annual Report 2024 |
| Analyst peak sales estimate for retatrutide | USD 25–40 billion/year | Evaluate Pharma; Jefferies Research 2025 |
Retatrutide's anticipated superiority in weight reduction over tirzepatide positions it as a potential blockbuster even within an already competitive market. Key commercial dynamics include:
- Differentiation via efficacy: 24%+ weight loss at 48 weeks, with plateau not yet reached, provides a clear clinical narrative over existing options.
- Obesity as a chronic disease: WHO's 2022 reclassification of obesity shifts payer coverage dynamics toward long-term pharmacotherapy reimbursement.
- GLP-1 supply chain investment: Eli Lilly has committed over USD 23 billion in manufacturing capacity expansion (2023–2027), specifically for incretin-class medicines.
- Competitive pressure from Novo Nordisk: CagriSema (cagrilintide + semaglutide) Phase 3 data (25.2% at 68 weeks) will represent a direct comparator at launch.
Regulatory Timeline Statistics
Retatrutide is currently in Phase 3 clinical development. The following timeline reflects publicly available data from ClinicalTrials.gov, Eli Lilly investor presentations, and FDA communications.
| Milestone | Date / Status | Source |
|---|---|---|
| First-in-human studies initiated | 2019 | Eli Lilly pipeline disclosures |
| Phase 2 SURMOUNT obesity trial complete | Q2 2023 | NEJM publication July 2023 |
| Phase 2 type 2 diabetes trial complete | Q3 2023 | Nature Medicine October 2023 |
| FDA Fast Track Designation (obesity) | 2023 | Eli Lilly press release |
| TRIUMPH Phase 3 program initiated | Q4 2023 – Q1 2024 | ClinicalTrials.gov |
| TRIUMPH Phase 3 enrollment complete | Q1 2026 | Eli Lilly Q4 2025 earnings call |
| Primary endpoint data (TRIUMPH-1/2) | Expected H2 2026 | Eli Lilly 2026 guidance |
| NDA/BLA submission target (obesity) | 2027 | Analyst consensus; Eli Lilly pipeline |
| FDA PDUFA date / approval target | 2027–2028 | Estimated (no FDA filing yet) |
| Ex-US regulatory submissions | EMA / TGA: 2027–2028 expected | Eli Lilly pipeline |
FDA Fast Track designation reduces review time and allows rolling NDA submission — meaning Eli Lilly can submit completed sections of the application before the full dossier is assembled, potentially accelerating approval by 3–6 months.
Summary Statistics Table
The table below consolidates the most-cited retatrutide statistics in a single reference. All figures use the 12 mg dose (highest studied) unless noted.
| Statistic | Value | Source |
|---|---|---|
| Mean weight loss at 48 weeks (12 mg) | 24.2% | NEJM 2023 |
| Placebo-corrected weight loss (12 mg) | 22.8 percentage points | NEJM 2023 |
| Participants achieving ≥5% weight loss | 100% | NEJM 2023 |
| Participants achieving ≥10% weight loss | 93% | NEJM 2023 |
| Participants achieving ≥15% weight loss | 83% | NEJM 2023 |
| Participants achieving ≥20% weight loss | ~62% | NEJM 2023 (estimated from figures) |
| Waist circumference reduction (12 mg) | −19.6 cm | NEJM 2023 |
| Nausea incidence (12 mg) | 60% | NEJM 2023 |
| Discontinuation due to AEs (12 mg) | 16% | NEJM 2023 |
| Receptor targets | GLP-1, GIP, Glucagon | Eli Lilly pipeline |
| Dosing regimen | Once weekly subcutaneous injection | Phase 2 protocol |
| Plateau reached at 48 weeks? | No — trajectory still declining | NEJM 2023 Fig. 2 |
| Phase 3 program | TRIUMPH (8 studies) | ClinicalTrials.gov |
| FDA Fast Track designation | Yes (obesity + T2D) | Eli Lilly |
| Expected NDA submission | 2027 | Analyst consensus |
| Expected US approval | 2027–2028 | Analyst consensus |
| Peak annual sales estimate | USD 25–40 billion | Jefferies; Evaluate Pharma |
| Global obesity market (2030) | USD 130+ billion | Goldman Sachs 2024 |
Methodology and Data Sources
This statistics page was compiled from the following primary and secondary sources. We update figures when new peer-reviewed data or official regulatory filings supersede earlier data.
- Jastreboff AM et al. "Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial." N Engl J Med. 2023;389(6):514-526. DOI: 10.1056/NEJMoa2301972
- Rosenstock J et al. "Retatrutide, a GIP, GLP-1 and Glucagon Receptor Agonist, for People with Type 2 Diabetes." Nature Medicine. 2023;29:2841-2850.
- Wilding JPH et al. "Once-Weekly Semaglutide in Adults with Overweight or Obesity." N Engl J Med. 2021;384:989-1002. (STEP 1)
- Jastreboff AM et al. "Tirzepatide Once Weekly for the Treatment of Obesity." N Engl J Med. 2022;387:205-216. (SURMOUNT-1)
- Eli Lilly Annual Report 2024. Indianapolis, Indiana: Eli Lilly and Company, 2025.
- ClinicalTrials.gov. TRIUMPH Phase 3 Program. NCT06051396 and related registrations.
- WHO Global Health Observatory. Obesity data 2025.
- Goldman Sachs Research. "The GLP-1 Opportunity." 2024.
- Fortune Business Insights. "Obesity Drug Market Size, Share & COVID-19 Impact Analysis." 2025.
Limitations: Retatrutide Phase 3 data are not yet published (expected H2 2026). All Phase 2 statistics represent a smaller, shorter-duration study than pivotal Phase 3 programs for semaglutide and tirzepatide. Direct numerical comparisons across trials are observational only and may be confounded by population differences. Market projections are analyst estimates and subject to revision.
For research use — see our full research library and the retatrutide product page for protocol-level detail.