What were retatrutide's actual results in clinical trials?

In the Phase 2 obesity trial (Jastreboff et al., NEJM, 2023), the 12 mg group lost a mean of 24.2% of body weight at 48 weeks, compared with 2.1% on placebo. Results were dose-dependent across the four doses studied (1 mg, 4 mg, 8 mg, and 12 mg), with the largest mean loss at the top dose.

What percentage of people actually respond to retatrutide?

At 48 weeks on the 12 mg dose, 100% of participants lost at least 5% of body weight, 93% reached at least 10%, and 83% reached at least 15%, versus 27%, 9%, and 2% on placebo at those same thresholds.

Did retatrutide improve anything besides weight?

Yes. The Phase 2 trial reported secondary improvements alongside weight loss, including reductions in liver fat measured by MRI-PDFF, improvements in triglycerides and blood pressure, and, in participants with type 2 diabetes in the broader program, meaningful A1C reductions.

Are retatrutide's Phase 3 results published yet?

The Phase 3 program (the TRIUMPH studies) is designed to confirm the Phase 2 signal in larger, longer trials. As of this writing, Modern Bio treats specific Phase 3 topline figures as unconfirmed until they appear in a peer-reviewed publication or a verifiable primary disclosure, and does not report numbers from secondary sources.

Why do my results look different from the trial average?

The trial mean summarizes a distribution, not a guarantee. Individual results scatter around it based on dose reached, how closely the titration schedule was followed, starting body weight, and normal biological variability, which is why the responder-rate breakdown is often more useful than the single headline percentage.

Retatrutide Results: What the Trial Data Actually Shows, by Dose

"Retatrutide results" is a broad search, and it gets answered with a single number more often than it should. The 24.2% figure from the Phase 2 trial is real, but it is a mean from one dose arm at one timepoint, inside a trial that measured a lot more than that. This post goes through what the trial data actually reported: results by dose, how many people responded and by how much, what happened beyond the scale, and what is and is not confirmed yet from the Phase 3 program.

It is written for research and educational purposes. Everything here reports what the published clinical literature describes; none of it is medical advice, and retatrutide is not approved for human use.

What "results" means in the retatrutide trials

Before comparing numbers, it helps to know what was actually measured. The Phase 2 obesity trial (Jastreboff et al., NEJM, 2023) randomized participants with obesity to placebo or one of four retatrutide doses (1 mg, 4 mg, 8 mg, and 12 mg) for 48 weeks, with mean percent change in body weight as the primary endpoint. ^[1] A separate, earlier phase 1b trial in people with type 2 diabetes measured a 12-week weight endpoint at lower doses. ^[3] Those are two different trials with two different populations, which is why a "12-week result" and a "48-week result" are not directly comparable numbers, only complementary data points.

Phase 2 results by dose, 48 weeks

Dose	Mean weight loss at 48 weeks	vs placebo
Placebo	2.1%	(reference)
1 mg	Smallest of the four active doses tested	Numerically greater than placebo
4 mg	Intermediate	Numerically greater than the 1 mg arm
8 mg	Intermediate to high	Numerically greater than the 4 mg arm
12 mg	24.2%, the largest reduction reported	+22.1 percentage points vs placebo

The table above intentionally states the 1 mg, 4 mg, and 8 mg results qualitatively rather than with exact percentages. The 12 mg figure (24.2%) and the placebo figure (2.1%) are the two numbers Modern Bio has independently confirmed against the primary NEJM publication for this article; the intermediate-dose percentages exist in the same paper but were not independently re-verified against the source table in this writing pass, so they are described directionally here rather than quoted as precise figures. The confirmed shape of the result still stands: weight loss increased in an orderly, stepwise pattern from the lowest to the highest dose. ^[1]

How many people actually responded

A mean can hide a lot of spread. The more useful number for most people asking "what results can I expect" is the responder rate: the share of participants who reached a given threshold, not just the average across everyone.

Responder rates at 48 weeks, 12 mg vs placebo

Threshold reached	12 mg retatrutide	Placebo
At least 5% body weight loss	100%	27%
At least 10% body weight loss	93%	9%
At least 15% body weight loss	83%	2%

Two things stand out in that table. First, on the 12 mg dose, every single participant reached at least the 5% threshold, which is a materially different finding than "the average person lost weight." Second, the gap between retatrutide and placebo widens as the threshold gets harder to reach: at 5% the groups are far apart, and by 15% they are in different categories entirely. That pattern is what a real, mechanism-driven effect looks like, as opposed to a shift that is mostly noise around a small average difference. ^[1]

I went into this expecting to land somewhere near the average, because that is how I had been thinking about the 24.2% number, as a prediction rather than a mean. It took reading the actual responder table to recalibrate. I was on the higher end of the dose range and logged my weight weekly against the trial's reported timepoints instead of comparing myself day to day.

The biggest surprise was how closely the shape of my curve matched the trial's, not the exact percentage but the pattern: a slow first month, a clear acceleration once I was at steady state, and a steadier climb after that rather than a straight line. By week 24 my trend was tracking inside the range the 8 to 12 mg arms reported, which made the whole thing feel less like a guess and more like I was reproducing a documented result.

The other thing that helped was not fixating on the single headline percentage. Once I looked at the responder-rate breakdown instead, I stopped treating any one week's number as a verdict and started treating the trend line as the actual signal.

— Priya Nagarajan, Austin, TX

Results beyond the scale

Body weight is the headline endpoint, but the Phase 2 trial tracked a set of secondary measures, and they moved in the same direction. Reported alongside the weight results were reductions in liver fat (measured by MRI-derived proton density fat fraction), improvements in triglycerides and blood pressure, and, in the broader program's participants with type 2 diabetes, meaningful glycemic (A1C) improvements. ^[1]

Mechanistically, this fits the compound's design. The glucagon receptor arm, the third target that distinguishes retatrutide from dual GLP-1/GIP agonists, contributes an energy-expenditure and lipid-mobilization effect, which is exactly where you would expect liver-fat and triglyceride changes to show up, layered on top of the appetite and glucose effects the incretin receptors provide. The full mechanism is covered in how retatrutide works.

How retatrutide's results compare to semaglutide and tirzepatide

The most common framing question is how the 24.2% figure stacks up against the compounds researchers already know.

Class comparison, separate trials

Compound	Receptors	Mean weight loss (top dose)	Trial
Semaglutide	GLP-1	approximately 15%	STEP 1 ^[5]
Tirzepatide	GLP-1 / GIP	approximately 21%	SURMOUNT-1 ^[4]
Retatrutide	GLP-1 / GIP / glucagon	24.2%	Phase 2 ^[1]

These are separate trials with separate populations, not a head-to-head study, so the comparison describes a pattern rather than proof that any one receptor caused any specific fraction of the difference. The pattern itself, more receptor coverage tracking with a larger mean result, is consistent across all three trials, which is the strongest indirect evidence that the added glucagon arm is contributing something real. A full side-by-side is in retatrutide vs semaglutide and retatrutide vs tirzepatide.

Where the Phase 3 program stands

Phase 2 establishes a signal; Phase 3 is where a compound has to hold up in a larger, longer, more diverse trial population, and it is the data that regulatory review actually turns on. Retatrutide's Phase 3 program, referred to in the literature as the TRIUMPH studies, is designed to confirm the Phase 2 result at scale and characterize longer-term safety.

Some competitor sites currently cite specific Phase 3 topline percentages. Modern Bio's editorial standard is to report a trial figure only once it is independently verifiable against a primary source (a peer-reviewed publication or a verifiable company disclosure), not a secondary summary. As of this writing, that verification has not been completed for any specific Phase 3 percentage, so none is reported here. This section will be updated with a cited figure once one is confirmed against a primary source.

Why individual results vary from the trial mean

The trial mean and responder rates describe a study population, not a single person, and several factors explain why an individual trajectory can look different from either.

Dose reached. The dose-response pattern in the Phase 2 data means the 1 mg and 12 mg arms are not interchangeable comparisons; the dose actually reached matters more than the protocol's nominal top dose.
Titration adherence. Skipping steps or moving through the escalation schedule faster than studied changes both tolerability and, potentially, the exposure curve behind the reported results.
Time in protocol. Results at 12 weeks, 24 weeks, and 48 weeks are three different numbers in the trial itself; comparing an early personal reading against the 48-week headline figure will understate progress. The week-by-week timeline and the 3-month results breakdown cover the by-timepoint data in detail.
Starting body weight and normal biological variability, both of which produce a spread around any trial mean in any pharmacology study.
Tolerability. A protocol interrupted by side effects such as headache or gastrointestinal effects during titration accumulates less total exposure than one completed on schedule, which can show up as a smaller measured result.

Retatrutide results and online anecdotes

Searches for retatrutide results commonly turn up forum posts and social threads alongside the trial data. Those accounts are real to the people posting them, but they are uncontrolled, self-reported, and rarely disclose dose, adherence, or measurement method, which is precisely what the trial's protocol controls for. Treat forum results as anecdotes that can suggest a hypothesis worth checking against the published data, not as a substitute for the responder-rate and dose-response figures above.

Common mistakes that distort perceived results

Comparing a personal early-week number against the 48-week trial headline, which compares two different timepoints as if they were the same measurement.
Reading the mean percentage as an individual guarantee rather than a population average with a documented spread (the responder-rate table above).
Treating a stalled week as a failed protocol rather than checking it against the trial's known non-linear curve. The when results stall breakdown covers this specifically.
Skipping or rushing titration and then comparing the outcome to a trial arm that completed the full escalation schedule.

More on avoiding these is in common mistakes that slow results.

Frequently asked questions

What were retatrutide's actual results in clinical trials?: In the Phase 2 obesity trial (Jastreboff et al., NEJM, 2023), the 12 mg group lost a mean of 24.2% of body weight at 48 weeks, compared with 2.1% on placebo. Results were dose-dependent across the four doses studied (1 mg, 4 mg, 8 mg, and 12 mg), with the largest mean loss at the top dose.
What percentage of people actually respond to retatrutide?: At 48 weeks on the 12 mg dose, 100% of participants lost at least 5% of body weight, 93% reached at least 10%, and 83% reached at least 15%, versus 27%, 9%, and 2% on placebo at those same thresholds.
Did retatrutide improve anything besides weight?: Yes. The Phase 2 trial reported secondary improvements alongside weight loss, including reductions in liver fat measured by MRI-PDFF, improvements in triglycerides and blood pressure, and, in participants with type 2 diabetes in the broader program, meaningful A1C reductions.
Are retatrutide's Phase 3 results published yet?: The Phase 3 program (the TRIUMPH studies) is designed to confirm the Phase 2 signal in larger, longer trials. As of this writing, Modern Bio treats specific Phase 3 topline figures as unconfirmed until they appear in a peer-reviewed publication or a verifiable primary disclosure, and does not report numbers from secondary sources.
Why do my results look different from the trial average?: The trial mean summarizes a distribution, not a guarantee. Individual results scatter around it based on dose reached, how closely the titration schedule was followed, starting body weight, and normal biological variability, which is why the responder-rate breakdown is often more useful than the single headline percentage.

Glossary

Responder rate: The share of trial participants who reached a specific outcome threshold, such as at least 10% body weight loss, as opposed to the average result across the whole group.
Primary endpoint: The main outcome a trial is designed and powered to measure, in retatrutide's Phase 2 trial the mean percent change in body weight at 48 weeks.
Secondary endpoint: An additional outcome tracked alongside the primary endpoint, such as liver fat, triglycerides, or A1C in the retatrutide trials.
MRI-PDFF: Magnetic resonance imaging proton density fat fraction, an imaging method used to measure liver fat noninvasively.
Dose-response: A pattern where a larger dose produces a larger measured effect, evidence that an observed result is driven by the compound rather than chance.
Phase 3 trial: The larger, longer, confirmatory stage of clinical testing that follows Phase 2, designed to verify efficacy and characterize safety at scale.

References

Jastreboff AM, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity: A Phase 2 Trial. New England Journal of Medicine. 2023;389(6):514-526.
Coskun T, et al. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss: preclinical and clinical characterization. Cell Metabolism. 2022;34(9):1234-1247.
Urva S, et al. LY3437943, a novel triple GIP, GLP-1, and glucagon receptor agonist in people with type 2 diabetes: a phase 1b trial. The Lancet. 2022;400(10366):1869-1881.
Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). New England Journal of Medicine. 2022;387(3):205-216.
Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). New England Journal of Medicine. 2021;384(11):989-1002.

For research and educational purposes only. Not medical advice. Trial figures describe published clinical studies; cross-compound comparisons are drawn from separate trials, not head-to-head studies. Retatrutide is investigational and is not approved for human use.