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Retatrutide Results: Weight Loss Data and What to Expect

Retatrutide Results: Weight Loss Data and What to Expect

Last updated: August 2026

Overview

Retatrutide has produced the largest weight loss results of any obesity drug tested in clinical trials to date. In TRIUMPH-1 — the pivotal Phase 3 obesity trial, which reported topline results on May 21, 2026 — participants on the highest dose lost an average of 28.3% of their body weight (70.3 lbs) at 80 weeks Evidence: Phase 3 RCT, against 2.2% on placebo.
TRIUMPH-4, a smaller Phase 3 trial in adults with obesity and knee osteoarthritis, was the first Phase 3 readout and reported 28.7% among completers at 68 weeks. Both numbers are below.

This page consolidates all published weight loss data from retatrutide clinical trials, explains how results varied by dose and population, and provides realistic context for what individual results might look like.

Evidence strength — how solid the data behind each labelled claim is, strongest to weakest: Evidence: Phase 3 RCTEvidence: Phase 2Evidence: Phase 1 PKEvidence: PreclinicalEvidence: Community-reportedEvidence: Estimate

Phase 3 Results: TRIUMPH-1 (May 2026)

TRIUMPH-1 is the pivotal Phase 3 obesity trial — the largest retatrutide trial reported to date and the one the obesity filing rests on. It randomized 2,339 participants over 80 weeks, with a 104-week extension in 532 participants with a BMI of 35 or higher.
DoseMean weight loss at 80 weeksAbsolute weight loss
Placebo-2.2%-5.5 lbs
4 mg-19.0%-47.2 lbs
9 mg-25.9%-64.4 lbs
12 mg-28.3%-70.3 lbs

Two further results from the same readout:

  • 45.3% of participants on the 12 mg dose achieved 30% or more weight loss — a threshold approaching what bariatric surgery delivers.
  • In the 104-week extension (participants with BMI 35 or higher), the 12 mg group lost 30.3% (85.0 lbs). This is a different subgroup from the 80-week population, not a continuation of the same average — but it is the longest retatrutide exposure reported so far.
ClinicalTrials.gov lists TRIUMPH-1 (NCT05929066) as completed, with primary completion on April 6, 2026. Additional results were presented at the 86th annual American Diabetes Association Scientific Sessions.
Source: Eli Lilly press release, May 21, 2026

Phase 3 Results: TRIUMPH-4 (December 2025)

TRIUMPH-4 was the first Phase 3 trial to report results. It enrolled 445 adults with obesity (or overweight with complications) and knee osteoarthritis.

Measure9 mg12 mgPlacebo
Mean weight loss (completers)-26.4%-28.7%-2.1%
Mean weight loss (all randomized)-21.7%-23.7%-1.6%
Absolute weight loss-29.1 kg (64.2 lbs)-32.3 kg (71.2 lbs)—
Treatment duration68 weeks68 weeks68 weeks
Participants148148149

The "completers" number (28.7%) reflects participants who stayed on treatment for the full 68 weeks. The "all randomized" number (23.7%) includes everyone, even those who stopped treatment early. Both numbers are clinically meaningful.

Source: Eli Lilly press release, December 2025

Phase 3 Results: TRIUMPH-2 and TRIUMPH-3 (July 2026)

Lilly reported topline results from two additional Phase 3 trials on July 23, 2026. TRIUMPH-2 studied adults with obesity or overweight and type 2 diabetes; TRIUMPH-3 studied adults with severe obesity and established cardiovascular disease. Both trials met their primary weight-loss endpoint, but Lilly said detailed results would be presented at future medical meetings and published in peer-reviewed journals.

TRIUMPH-2: Obesity with type 2 diabetes

TRIUMPH-2 randomized 1,152 participants for 80 weeks. The trial studied 4 mg, 9 mg, and 12 mg retatrutide against placebo.
DoseMean weight loss at 80 weeksA1C change at 80 weeks
Placebo-4.0%-0.2%
4 mg-12.7%-1.4%
9 mg-19.1%-1.6%
12 mg-20.8%-1.5%
The 12 mg group lost an average of 49.6 pounds. The 9 mg arm had the largest A1C reduction in the release's table, so the glycemic and weight-loss results did not follow exactly the same dose pattern.

TRIUMPH-3: Obesity with established cardiovascular disease

TRIUMPH-3 randomized 1,949 participants for 80 weeks. It studied 9 mg and 12 mg retatrutide against placebo in adults with severe obesity and established cardiovascular disease.
DoseMean weight loss at 80 weeksAbsolute weight loss
Placebo-3.2%-7.7 lbs
9 mg-21.6%-52.7 lbs
12 mg-22.6%-55.8 lbs
At the highest dose, Lilly reported average reductions of 37.0% in triglycerides, 16.5% in non-HDL cholesterol, 9.3 mmHg in systolic blood pressure, 7.5 inches in waist circumference, and 51.2% in hsCRP. These are cardiometabolic risk-factor results from a population that already had cardiovascular disease, not evidence that retatrutide prevents cardiovascular events.
ClinicalTrials.gov now lists both studies as Completed, with actual enrollment of 1,152 for TRIUMPH-2 and 1,946 for TRIUMPH-3; the registry records do not yet contain posted results. The topline release reported hazard ratios for cardiovascular event composites, but the separate event-driven TRIUMPH-Outcomes trial is the program's cardiovascular and kidney outcomes study.
Sources: Eli Lilly, July 23, 2026; ClinicalTrials.gov v2 — NCT05929079; ClinicalTrials.gov v2 — NCT05882045; ClinicalTrials.gov v2 — NCT06383390

Phase 2 Results: Obesity Trial (NEJM 2023)

The Phase 2 obesity trial enrolled 338 adults without diabetes and tested multiple dose levels over 48 weeks. This trial provided the first detailed dose-response data for retatrutide.

DoseMean Weight Loss at 24 WeeksMean Weight Loss at 48 Weeks
Placebo-2.1%-2.1%
1 mg-6.0%-8.7%
4 mg (from 2 mg start)-9.4%-17.1%
4 mg (from 4 mg start)-9.0%-17.5%
8 mg (from 2 mg start)-16.3%-22.8%
8 mg (from 4 mg start)-14.2%-22.1%
12 mg (from 2 mg start)-16.7%-24.2%
12 mg (from 4 mg start)-15.0%-22.8%
A critical observation: weight loss had not plateaued at 48 weeks. Participants were still losing weight when the trial ended. The Phase 3 TRIUMPH-4 trial, which ran for 68 weeks, confirmed this — the 12mg group reached 28.7% weight loss at 68 weeks versus 24.2% at 48 weeks in Phase 2.
Source: Jastreboff et al., NEJM 2023

Phase 2 Results: Type 2 Diabetes Trial (Lancet 2023)

The Phase 2 type 2 diabetes trial enrolled 281 adults with T2D and tested retatrutide over 36 weeks.

Measure12 mg DosePlacebo
Weight loss-16.94%—
HbA1c reduction-2.02 percentage points-0.01%
Participants reaching HbA1c under 5.7%67%—

Weight loss was lower in the diabetes population than in the obesity trial — a consistent pattern across all GLP-1 drugs. Patients with type 2 diabetes typically lose less weight on anti-obesity medications, likely because insulin resistance and metabolic dysfunction make fat loss more difficult.

Source: Rosenstock et al., The Lancet 2023

Weight Loss Timeline: When Results Appear

Based on the Phase 2 trial data, here is approximately when weight loss milestones were reached at the 12mg dose:

TimepointApproximate Weight Loss (12 mg)What's Happening
Weeks 1-4~1-2%Starting dose (1 mg), appetite reduction begins
Weeks 5-12~4-8%Dose escalation (2 mg then 4 mg), noticeable weight change
Weeks 13-20~10-16%Dose escalation to 8 mg then 12 mg, rapid weight loss phase
Weeks 21-36~16-22%Maintenance dose, steady weight loss continues
Weeks 37-48~22-24%Weight loss continues but pace begins to slow
Weeks 49-68~24-29%Continued loss (Phase 3 data), approaching plateau

The timeline shows that retatrutide's weight loss is gradual and cumulative. Most participants did not see dramatic changes in the first month — the major weight loss occurred after reaching the target dose and continuing on it for months.

TRIUMPH-1 extends this curve past the Phase 2 window: 28.3% at 80 weeks on the 12 mg dose, and 30.3% at 104 weeks in the BMI-35-and-above extension group.

How Retatrutide Results Compare

DrugTrialDurationMax Weight Loss
Retatrutide 12 mgTRIUMPH-1 (Phase 3, pivotal obesity)80 weeks-28.3%
Retatrutide 12 mgTRIUMPH-4 (Phase 3)68 weeks-28.7%
Retatrutide 12 mgPhase 2 (NEJM)48 weeks-24.2%
Tirzepatide 15 mg (Zepbound)SURMOUNT-1 (Phase 3)72 weeks-22.5%
Semaglutide 2.4 mg (Wegovy)STEP 1 (Phase 3)68 weeks-14.9%
CagriSemaPhase 368 weeks-22.7%
Oral Wegovy 25 mgOASIS 468 weeks~17%

Retatrutide's results exceed all currently approved and most investigational obesity drugs. The gap between retatrutide and Wegovy (~14 percentage points) is substantial — roughly the difference between losing 70 pounds versus 37 pounds for a 250-pound starting weight.

Important caveat: these are cross-trial comparisons, not head-to-head data. The patient populations, trial designs, and baseline characteristics differ across studies. No published trial has directly compared retatrutide to tirzepatide or semaglutide.

What Individual Results Look Like

Clinical trial averages are useful but do not tell the full story. Individual results vary significantly.

The range of outcomes

In the Phase 2 trial at the 12mg dose:

  • Some participants lost more than 30% of their body weight
  • The average was 24.2% at 48 weeks
  • A small number of participants lost less than 10%
  • Placebo group averaged 2.1% weight loss

Factors that influence individual results

Based on GLP-1 drug class data and the retatrutide trials specifically:

  • Dose: Higher doses produce greater average weight loss. The difference between 4mg (-17%) and 12mg (-24%) in Phase 2 was significant.
  • Treatment duration: Weight loss was still increasing at 48 weeks in Phase 2 and at 68 weeks in Phase 3. Longer treatment produces more weight loss.
  • Starting weight and metabolic health: Participants with type 2 diabetes lost less weight (-16.9% at 12mg) than those without diabetes (-24.2%).
  • Adherence and tolerability: Participants who discontinue treatment due to side effects obviously achieve less weight loss. In TRIUMPH-4, 18.2% of the 12mg group discontinued due to adverse events.
  • Lifestyle factors: All clinical trials included lifestyle counseling (reduced calorie diet and increased physical activity). The extent to which individual participants followed this guidance varied.

Trial participant reports

While not systematic data, reports from TRIUMPH trial participants provide additional context: Evidence: Community-reported
  • One TRIUMPH-1 participant reported losing 30.6% of body weight (approximately 75 pounds) after one year on the trial, going from XL/2XL shirts to medium and fitting into size 32 pants for the first time in 20 years
  • The same participant reported cholesterol down 30-33%, triglycerides down 70%, blood pressure normalized, fatty liver disease resolved (confirmed by CT scan), and asthma symptoms eliminated
  • These individual results are consistent with the upper range of clinical trial outcomes and should not be taken as typical

Beyond Weight Loss: Other Results

TRIUMPH-4 measured outcomes beyond the scale:

Cardiovascular markers

MarkerChange at 12 mg
Systolic blood pressure-14.0 mmHg
Non-HDL cholesterolSignificant reduction (exact % pending full publication)
TriglyceridesSignificant reduction
High-sensitivity CRP (inflammation)Significant reduction

Knee osteoarthritis outcomes (TRIUMPH-4 specific)

Measure9 mg12 mgPlacebo
WOMAC pain score reduction4.5 points (75.8%)4.4 points (73.8%)2.4 points
Completely pain-free14.1%12.0%4.0%

Liver fat (Phase 2 sub-study)

A sub-study of the Phase 2 trial measured liver fat by MRI and found reductions of up to 82.4% at the highest dose — among the strongest liver fat reduction results for any drug in development. For details, see Retatrutide and Fatty Liver Disease.

Blood sugar control (Phase 2 T2D trial)

In patients with type 2 diabetes, retatrutide reduced HbA1c by 2.02 percentage points, with 67% of participants reaching normoglycemic levels (HbA1c below 5.7%). For details, see Retatrutide for Type 2 Diabetes.

Setting Realistic Expectations

What the averages mean

An average weight loss of 28.7% means that roughly half of participants lost more than this amount and half lost less. The distribution is not symmetrical — a few participants may have lost very little (possibly due to early discontinuation), while many achieved results in the 20-35% range.

The completers vs intention-to-treat gap

TRIUMPH-4 reported two sets of numbers:

  • Completers (28.7%): Participants who stayed on treatment for the full 68 weeks
  • All randomized (23.7%): Everyone, including those who dropped out

The 5-percentage-point gap reflects the real-world challenge of adherence. Not everyone tolerates the drug well enough to complete the full course. If you stay on treatment, results are significantly better.

Weight loss does not happen overnight

The Phase 2 weight loss curve shows a gradual trajectory. At 24 weeks (6 months), participants on 12mg had lost approximately 16.7% — substantial but less than half the eventual 48-week result. The first 4-8 weeks produce relatively modest changes as the dose titrates up.

No trial has tested maintenance yet

TRIUMPH-6 is studying weight maintenance after initial treatment, but results are not yet available. For all existing GLP-1 drugs, discontinuing treatment leads to significant weight regain. There is no reason to expect retatrutide would be different. Long-term treatment is likely required to maintain results.

Upcoming Results to Watch

Already reported: TRIUMPH-4 (December 2025), TRIUMPH-1 (May 21, 2026) — the pivotal obesity trial, covered above — and TRIUMPH-2 and TRIUMPH-3 (both July 23, 2026):
  • TRIUMPH-2 (obesity in type 2 diabetes, nested sleep-apnea protocol): -20.8% at 12 mg, -19.1% at 9 mg and -12.7% at 4 mg over 80 weeks, versus -4.0% on placebo, with A1C down up to 1.6%. Weight loss runs lower here than in TRIUMPH-1 — expected in a type 2 diabetes population.
  • TRIUMPH-3 (obesity in cardiovascular disease): -22.6% at 12 mg and -21.6% at 9 mg over 80 weeks, versus -3.2% on placebo, in adults with severe obesity and established cardiovascular disease. Full results.

Still to read out:

  • TRIUMPH-5 (head-to-head vs tirzepatide, NCT06662383): Body-weight efficacy comparison in obesity (~800 participants)
  • TRIUMPH-6 (weight maintenance): The trial that will answer what happens after treatment
  • TRIUMPH-Outcomes (CV/renal outcomes, NCT06383390): Long-term CV composite (CV death, non-fatal MI, non-fatal stroke, and heart-failure events) plus kidney endpoints (~10,000 participants; primary completion ~2029)
  • Phase 3 MASLD master protocol (NCT07165028): Multi-agent MASLD program that includes retatrutide (not a dedicated retatrutide-only liver trial)
  • Additional TRIUMPH trials: Chronic low back pain, and the TRANSCEND-T2D type 2 diabetes program
Note: the type 2 diabetes data comes from the separate TRANSCEND-T2D program, not TRIUMPH-3 — TRIUMPH-3 is the cardiovascular-disease population.
For trial-by-trial tracking, see Clinical Trials & Results.

Frequently Asked Questions

How much weight can you lose on retatrutide?

In TRIUMPH-1 — the pivotal Phase 3 obesity trial, reported May 21, 2026 — participants on the 12 mg dose lost an average of 28.3% of their body weight (70.3 lbs) at 80 weeks, versus 2.2% on placebo. At 9 mg the average was 25.9%, and at 4 mg it was 19.0%. Individual results ranged widely: 45.3% of the 12 mg group lost 30% or more of their body weight.

The earlier Phase 3 TRIUMPH-4 trial, in adults with obesity and knee osteoarthritis, reported 28.7% at 12 mg among participants who completed 68 weeks.

What did the pivotal Phase 3 obesity trial show?

TRIUMPH-1 randomized 2,339 participants for 80 weeks and reported topline results on May 21, 2026. Mean weight loss was 28.3% at 12 mg (70.3 lbs), 25.9% at 9 mg, and 19.0% at 4 mg, against 2.2% on placebo. 45.3% of the 12 mg group achieved 30% or more weight loss. In a 104-week extension of participants with a BMI of 35 or higher, the 12 mg group lost 30.3% (85.0 lbs) — the longest retatrutide exposure reported so far. ClinicalTrials.gov lists the trial (NCT05929066) as completed.

How long does it take to see results on retatrutide?

Based on Phase 2 trial data, noticeable weight loss typically begins within the first 4-8 weeks as the dose is titrated up. By 24 weeks (6 months), participants on the 12mg dose had lost approximately 16.7% of body weight. Weight loss continued through week 48 and beyond, with Phase 3 data showing continued loss through 68 weeks.

Is retatrutide better than Ozempic or Mounjaro for weight loss?

Retatrutide has produced larger average weight loss in clinical trials than both semaglutide (Ozempic/Wegovy, ~15-17%) and tirzepatide (Mounjaro/Zepbound, ~21-23%). However, no head-to-head trial has directly compared these drugs. Retatrutide is also still investigational and not yet available by prescription. For a detailed comparison, see Retatrutide vs Mounjaro vs Ozempic.

What do retatrutide before and after results look like?

Clinical trials measure weight loss as a percentage of starting body weight. For a 250-pound starting weight, the average results at 12mg would be approximately: -22 pounds at 12 weeks, -42 pounds at 24 weeks, -60 pounds at 48 weeks, and -72 pounds at 68 weeks. Individual variation is significant — some participants lost more than 30% of their body weight. No published trial has released individual before-and-after photographs.

Does the weight loss plateau?

In the Phase 2 trial, weight loss had not fully plateaued at 48 weeks. The Phase 3 TRIUMPH-4 trial showed continued weight loss through 68 weeks, though the rate of loss was beginning to slow. TRIUMPH-1 extended the picture further: 28.3% at 80 weeks at the 12 mg dose, and 30.3% at 104 weeks in the extension group (participants with a BMI of 35 or higher — a different subgroup, so the two figures are not a single continuous curve). When or whether weight loss fully plateaus with continued treatment is not yet established.

What happens when you stop taking retatrutide?

No published data addresses weight regain after retatrutide discontinuation. However, all GLP-1 class drugs (semaglutide, tirzepatide) show significant weight regain after stopping treatment. The TRIUMPH-6 trial is studying weight maintenance, but results are not yet available.

Sources

  • Jastreboff, A.M., et al. (2023). Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. New England Journal of Medicine. DOI: 10.1056/NEJMoa2301972
  • Rosenstock, J., et al. (2023). Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-comparator-controlled, parallel-group, phase 2 trial conducted in the USA. The Lancet. DOI: 10.1016/S0140-6736(23)01053-X
  • Eli Lilly and Company. (2026). Lilly's triple agonist retatrutide delivered powerful weight loss in pivotal Phase 3 obesity trial (TRIUMPH-1). May 21, 2026. Press release.
  • Eli Lilly and Company. (2025). Lilly's retatrutide achieved significant weight loss and pain relief in adults with obesity and knee osteoarthritis. Press release.
  • Eli Lilly and Company. (2026). Lilly's triple agonist, retatrutide, successful in two additional Phase 3 obesity trials (TRIUMPH-2 and TRIUMPH-3). July 23, 2026. Press release.
  • ClinicalTrials.gov. NCT05929079, NCT05882045, and NCT06383390 — current Phase 3 records for TRIUMPH-2, TRIUMPH-3, and TRIUMPH-Outcomes.
  • Harris, E. (2023). Triple-Hormone Combination Retatrutide Induces 24% Body Weight Loss. JAMA. DOI: 10.1001/jama.2023.12055.
  • ClinicalTrials.gov: NCT05929066 (TRIUMPH-1, Phase 3, Obesity — completed), NCT04881760 (Phase 2, Obesity), NCT04867785 (Phase 2, T2D)
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What this is
Educational information, not medical advice. It reports published research — it doesn’t recommend that you use, obtain, or supply anything.
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Retatrutide and similar peptides are investigational — not approved by the FDA or any regulator. Semaglutide and tirzepatide are prescription-only medicines, available only through a licensed prescriber.
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Do not make decisions about your health without consulting a qualified healthcare provider. For trial enrolment, see ClinicalTrials.gov. More on how we review.

Sources

Grounded in primary sources
NEJMThe LancetJAMAFDAClinicalTrials.gov