Retatrutide before and after: weight loss by dose and week in the trials

The short answer: in trials, retatrutide produced some of the largest average weight losses reported in obesity drug trials. In the phase 2 trial, the 12 mg dose led to a mean weight change of minus 24.2% at 48 weeks versus minus 2.1% on placebo. [1] In the first phase 3 obesity trial, TRIUMPH-1, company toplines report minus 28.3% at 80 weeks on 12 mg versus minus 2.2% on placebo. [2]

These are trial averages, not individual results, and most phase 3 figures are press releases that have not been peer reviewed. Retatrutide is not approved and is lawfully available only through clinical trials and a narrow expanded access program. This breakdown covers what the studies measured. It does not give dosing advice.

Retatrutide results by week: the phase 2 trial

The phase 2 obesity trial randomized 338 adults with a BMI of 30 or higher, or 27 to 30 with a weight-related condition, to weekly retatrutide or placebo for 48 weeks. [1]

At 24 weeks, mean weight change was: [1]

• 1 mg: minus 7.2%
• 4 mg: minus 12.9%
• 8 mg: minus 17.3%
• 12 mg: minus 17.5%
• Placebo: minus 1.6%

At 48 weeks, it was: [1]

• 1 mg: minus 8.7%
• 4 mg: minus 17.1%
• 8 mg: minus 22.8%
• 12 mg: minus 24.2%
• Placebo: minus 2.1%

The share of people crossing weight loss thresholds tells more than the average. On 12 mg, 100% lost at least 5%, 93% lost at least 10%, and 83% lost at least 15% by week 48. On placebo, the figures were 27%, 9%, and 2%. [1]

Retatrutide phase 3 results: TRIUMPH-1

TRIUMPH-1 randomized 2,339 adults with obesity or overweight and at least one weight-related condition, without diabetes, to 4 mg, 9 mg, or 12 mg or placebo for 80 weeks. Average baseline weight was 112.7 kg (248.5 lbs). [2]

Mean weight change at 80 weeks, efficacy estimand (as if everyone stayed on treatment): [2]

• 4 mg: minus 19.0% (minus 47.2 lbs)
• 9 mg: minus 25.9% (minus 64.4 lbs)
• 12 mg: minus 28.3% (minus 70.3 lbs)
• Placebo: minus 2.2% (minus 5.5 lbs)

Counting everyone regardless of whether they stayed on the drug (the treatment-regimen estimand), the figures were minus 17.6%, 23.7%, and 25.0% versus minus 3.9%. [2] The second number is closer to what a whole population would see, because some people stop treatment.

Thresholds at 80 weeks on 12 mg: 62.5% lost at least 25% of body weight, 45.3% at least 30%, and 27.2% at least 35%, compared with 2.2%, 0.5%, and 0.3% on placebo. Waist circumference fell by 24.1 cm on 12 mg versus 3.6 cm on placebo, and 65.3% of people on 12 mg ended the trial with a BMI under 30. [2]

A pre-specified extension followed 532 participants with a baseline BMI of 35 or higher to 104 weeks, reaching minus 30.3% on the 12 mg arm. [2] Read that figure with care: the extension enrolled only people who completed 80 weeks and tolerated their dose, so it describes the people who did best on treatment, not everyone who started.

Results in other phase 3 populations

Weight loss was smaller in people with type 2 diabetes, a pattern seen with every drug in the class.

• TRIUMPH-2 (obesity with type 2 diabetes), 80 weeks: minus 12.7%, 19.1%, and 20.8% on 4, 9, and 12 mg, with A1C reductions of up to 1.6 percentage points. [3]
• TRIUMPH-3 (severe obesity with cardiovascular disease), 80 weeks: up to minus 22.6%. [3]
• TRIUMPH-4 (obesity with knee osteoarthritis), 68 weeks: minus 26.4% on 9 mg and minus 28.7% on 12 mg versus minus 2.1% on placebo. [4]

The diabetes-specific trials, which enrolled people at lower average weights, report smaller percentages. In the 36-week phase 2 diabetes trial, weight fell by up to 16.94% on 12 mg versus 3.00% on placebo and 2.02% on dulaglutide 1.5 mg. [5] In TRANSCEND-T2D-1, a 40-week phase 3 trial in 537 adults, weight fell by 11.5%, 13.9%, and 15.3% on 4, 9, and 12 mg versus 2.6% on placebo. [6] See the type 2 diabetes condition page for how these compare with approved options.

Is the weight lost fat or muscle?

A body composition substudy of the phase 2 diabetes trial measured fat with DXA scans at 36 weeks. Total fat mass fell by 23.2% on 12 mg and 26.1% on pooled 8 mg, versus 4.5% on placebo and 2.6% on dulaglutide. [7] The authors reported that the proportion of lean mass lost relative to total weight lost was similar to other obesity treatments. [7] Some lean mass loss is expected with any large weight loss; the question for long-term health is how much, and the full phase 3 body composition data are not yet published.

How retatrutide results compare with tirzepatide and semaglutide

No published trial has compared retatrutide directly with an approved drug, so comparisons use separate trials with different populations and durations. For reference, tirzepatide produced minus 15.0%, 19.5%, and 20.9% at 72 weeks on 5, 10, and 15 mg versus minus 3.1% on placebo in SURMOUNT-1. [8] Our tirzepatide vs retatrutide and semaglutide vs retatrutide comparisons lay out each program side by side.

What happens when you stop?

No retatrutide withdrawal data have been published. A dedicated trial of retatrutide for maintaining weight reduction is registered and under way. [11]

The approved drugs suggest what to expect. One year after stopping semaglutide 2.4 mg in the STEP 1 extension, participants regained two-thirds of the weight they had lost. [9] In SURMOUNT-4, people who switched from tirzepatide to placebo after 36 weeks regained 14.0% over the next year, while those who continued lost a further 5.5%. [10] Obesity behaves like a chronic condition, and these drugs work while they are taken.

About before and after photos

Search results for "retatrutide before and after" are full of photos. They cannot be verified, they rarely state dose or duration, and because retatrutide is only lawfully available in trials, photos from outside a trial usually involve unapproved products. FDA has warned sellers of retatrutide falsely labeled for research use and urges consumers not to buy these products, which are of unknown quality. [12] The numbers above come from randomized, placebo-controlled trials with supervised dosing. Our peptide before and after guide explains how to read any results claim.

Where to go from here

Retatrutide has no lawful price or prescription path yet; see retatrutide cost and the regulatory tracker. For the only lawful routes, read how to get retatrutide. For tolerability, see retatrutide side effects, and for outcomes beyond weight, retatrutide benefits.

If you want treatment now, approved GLP-1 drugs are available by prescription. The GLP-1 hub lists them, the obesity condition page grades the evidence, and how to get peptides prescribed explains the lawful path. Our peptide therapy explainer shows how to tell an approved drug from a research-labeled one.