Retatrutide Results Timeline: What Studies Measured, and When
Published retatrutide research is dominated by two phase 2 randomised trials plus reviews and pooled analyses. The obesity trial measured percentage body-weight change at week 24 and again at week 48; the type 2 diabetes trial measured HbA1c at week 24 and additional endpoints at week 36. A substudy measured body composition, and phase 3 registrational trials have published designs but not results. This page describes those timepoints and what researchers reported, without predicting any individual outcome.
Questions about "when results appear" with retatrutide can only be answered in one way by the published literature: by describing the timepoints investigators chose to measure, the populations they studied, and what they reported at each of those visits. Retatrutide is an investigational triple agonist at the GIP, GLP-1 and glucagon receptors, and its human evidence base consists mainly of phase 2 randomised trials, secondary analyses of those trials, and reviews that place it alongside other incretin-based agents (Biomolecules, 2025). This page is for educational purposes only and is not medical advice; consult a licensed physician before making any health decisions.
The measurement calendar in the phase 2 obesity trial
The most cited timeline comes from a 48-week phase 2 randomised, double-blind, placebo-controlled trial in adults with obesity, or with overweight plus at least one weight-related condition, which assigned participants to placebo or once-weekly subcutaneous retatrutide at 1 mg, 4 mg (with a 2 mg starting dose), 4 mg, 8 mg (2 mg start), 8 mg (4 mg start) or 12 mg (2 mg start) (NEJM, 2023). The study set percentage change in body weight at week 24 as the primary endpoint and percentage change at week 48 as a key secondary endpoint, so the published "timeline" for that trial is essentially two snapshots plus the escalation schedule that preceded them (NEJM, 2023).
Researchers reported least-squares mean percentage weight changes at both visits, summarised below.
| Group | Mean change at week 24 | Mean change at week 48 | Source |
|---|---|---|---|
| Placebo | −1.6% | −2.1% | PMID 37366315 |
| Retatrutide 1 mg | −7.2% | −8.7% | PMID 37366315 |
| Retatrutide 4 mg (pooled) | −12.9% | −17.1% | PMID 37366315 |
| Retatrutide 8 mg (pooled) | −17.3% | −22.8% | PMID 37366315 |
| Retatrutide 12 mg | −17.5% | −24.2% | PMID 37366315 |
Two features of that table matter for anyone reading a timeline. First, the week-24 figures were recorded while several groups were still moving through dose escalation, so the 24-week values and the 48-week values in the higher-dose arms were not measured under identical exposure conditions (NEJM, 2023). Second, the group means continued to separate from placebo between week 24 and week 48 rather than flattening, and the trial ended at 48 weeks, so the published data do not describe what group averages did afterwards (NEJM, 2023). These are trial-level averages across randomised groups, not forecasts for any individual.
A different calendar in type 2 diabetes
The phase 2 trial in people with type 2 diabetes used a shorter schedule: a randomised, double-blind, placebo- and active-controlled, parallel-group design conducted in the USA, with dulaglutide 1.5 mg as the active comparator and a primary endpoint of HbA1c change from baseline at week 24 (Lancet, 2023). Secondary endpoints, including further glycaemic and body-weight measures, were assessed through week 36, which is where that study stopped collecting on-treatment efficacy data (Lancet, 2023). Researchers reported dose-dependent reductions in HbA1c at week 24 and dose-dependent reductions in body weight by week 36 in the retatrutide groups, with the largest mean changes in the highest-dose arms (Lancet, 2023).
The practical point for timeline questions is that glycaemic endpoints and weight endpoints were not measured on the same clock in that trial, and the diabetes population was studied for 36 weeks while the obesity population was studied for 48 weeks (Lancet, 2023)(NEJM, 2023). Comparing a 36-week diabetes figure with a 48-week obesity figure compares two different designs in two different populations.
Doing the math on a vial? The PeptideU app does reconstitution, units and dilution for you.
Try it freeBody composition: what was measured, and when
Weight on a scale is one measurement; what that weight consists of is another. A prespecified substudy of the phase 2 type 2 diabetes trial used imaging to quantify changes in body composition, and researchers reported reductions in fat mass alongside changes in lean tissue over the randomised treatment period (Lancet Diabetes & Endocrinology, 2025). That substudy is the main published source for compositional endpoints with this compound, and it was limited to the subset of participants who underwent imaging rather than the whole trial population (Lancet Diabetes & Endocrinology, 2025).
Broader commentary in the incretin field has examined whether resistance exercise can influence the lean-mass component of drug-induced weight loss, and that review discussed the evidence as an open question rather than a settled one (Diabetes Care, 2024). No published retatrutide trial has been designed to test an exercise-plus-drug timeline of that kind (Diabetes Care, 2024).
What pooled analyses added to the picture
Because the randomised evidence base is small, several groups have pooled or ranked it. A systematic review and meta-analysis of randomised controlled trials examined retatrutide for obesity and reported greater weight reduction with retatrutide than with placebo, together with a higher frequency of gastrointestinal adverse events (Proceedings, Baylor University Medical Center, 2025). A Bayesian network meta-analysis compared GLP-1 receptor agonists, dual agonists and retatrutide for weight loss in adults with overweight or obesity and reported rankings across those agents (Obesity, 2025). Network meta-analyses of this type align trials of differing lengths, so their outputs describe relative effects across a mixed set of follow-up windows rather than a single shared timepoint (Obesity, 2025).
Wider syntheses of the class supply context for how such timelines are usually constructed. A systematic review of randomised controlled trials of GLP-1 receptor agonists for weight loss in adults without diabetes examined efficacy and safety across trials of varying duration (Annals of Internal Medicine, 2025), while a Diabetes Care review of GLP-1 medicines for type 2 diabetes and obesity summarised efficacy and safety across the approved agents (Diabetes Care, 2024). A clinical review of weight-management treatment in obesity placed pharmacotherapy within lifestyle, behavioural and surgical options (Medicina Clinica, 2025), and a pipeline review described where triple agonists sit among candidate obesity medications still under investigation (International Journal of Obesity, 2025).
Tracking research? Log entries with dates, lots and notes — records, never plans.
Get the appTimepoints that are being measured now, but not yet reported
The next tranche of retatrutide timelines will come from phase 3. A design paper described the TRIUMPH registrational programme, which covers obesity, obstructive sleep apnoea and knee osteoarthritis, setting out the rationale, endpoints and planned assessments for those trials (Diabetes, Obesity & Metabolism, 2026). A design and rationale publication reports how a trial will be conducted, not what it found, so no outcome data should be read into it (Diabetes, Obesity & Metabolism, 2026). Reviews published while those trials were ongoing described retatrutide as investigational and awaiting phase 3 confirmation (Biomolecules, 2025).
Adverse Events Over Time: What Studies Report
Tolerability findings also carry timestamps. In the 48-week phase 2 obesity trial, researchers reported that the most common adverse events were gastrointestinal — including nausea, diarrhoea, vomiting and constipation — that they were mostly mild to moderate, that they were dose-related, and that they were partly mitigated by starting at a lower dose and escalating (NEJM, 2023). The phase 2 trial in type 2 diabetes similarly reported gastrointestinal adverse events as the most frequent, with a dose-dependent pattern (Lancet, 2023). Pooled randomised data likewise reported a higher incidence of gastrointestinal adverse events with retatrutide than with placebo (Proceedings, Baylor University Medical Center, 2025). Class-level reviews of GLP-1 medicines described gastrointestinal effects and treatment discontinuation as recurring safety themes across trials (Diabetes Care, 2024)(Annals of Internal Medicine, 2025). Because escalation schedules differ between arms and trials, the timing of these events in published reports reflects the protocol used, not a universal sequence.
Want the full course? Every compound, evidence-graded and cited, inside PeptideU.
Start learning freeReading a results timeline without over-reading it
- Group means are not individual trajectories. The week-24 and week-48 values in the obesity trial were least-squares means for randomised groups (NEJM, 2023).
- Phase 2 is not phase 3. Both randomised retatrutide trials to date were phase 2, and registrational trials are described only by design so far (NEJM, 2023)(Diabetes, Obesity & Metabolism, 2026).
- Populations differ. The obesity trial enrolled adults with obesity or overweight plus a weight-related condition (NEJM, 2023); the other trial enrolled adults with type 2 diabetes (Lancet, 2023).
- Follow-up ends when the trial ends. No published retatrutide trial has reported endpoints beyond 48 weeks (NEJM, 2023).
- Compositional change needs imaging. Fat and lean tissue changes were reported in a substudy, not in every participant (Lancet Diabetes & Endocrinology, 2025).
What the published literature does not establish
Several timeline questions have no published answer. There is no retatrutide trial reporting cardiovascular outcomes over multi-year follow-up, no published randomised withdrawal study describing what happens after treatment stops, and no head-to-head randomised comparison against tirzepatide or semaglutide with matched timepoints; comparative statements to date come from indirect network meta-analysis (Obesity, 2025). Reviews have consistently characterised the compound as investigational and dependent on the outcome of ongoing registrational work (Biomolecules, 2025)(International Journal of Obesity, 2025). Where evidence is absent, the honest description is that it is absent rather than inferred from a related molecule.
Doing the math on a vial? The PeptideU app does reconstitution, units and dilution for you.
Try it freeReferences
- Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial (The New England Journal of Medicine, 2023)
- Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial conducted in the USA (Lancet, 2023)
- Effects of retatrutide on body composition in people with type 2 diabetes: a substudy of a phase 2, double-blind, parallel-group, placebo-controlled, randomised trial (The Lancet Diabetes & Endocrinology, 2025)
- Retatrutide for the treatment of obesity, obstructive sleep apnea and knee osteoarthritis: Rationale and design of the TRIUMPH registrational clinical trials (Diabetes, Obesity & Metabolism, 2026)
- Efficacy and safety of retatrutide, a novel GLP-1, GIP, and glucagon receptor agonist for obesity treatment: a systematic review and meta-analysis of randomized controlled trials (Proceedings (Baylor University Medical Center), 2025)
- Efficacy and Safety of GLP-1 Receptor Agonists, Dual Agonists, and Retatrutide for Weight Loss in Adults With Overweight or Obesity: A Bayesian NMA (Obesity, 2025)
- Retatrutide-A Game Changer in Obesity Pharmacotherapy (Biomolecules, 2025)
- Efficacy and Safety of GLP-1 Medicines for Type 2 Diabetes and Obesity (Diabetes Care, 2024)
- Efficacy and Safety of Glucagon-Like Peptide-1 Receptor Agonists for Weight Loss Among Adults Without Diabetes: A Systematic Review of Randomized Controlled Trials (Annals of Internal Medicine, 2025)
- Incretin-Based Weight Loss Pharmacotherapy: Can Resistance Exercise Optimize Changes in Body Composition? (Diabetes Care, 2024)
- Weight management treatment in obesity (Medicina Clinica, 2025)
- What is the pipeline for future medications for obesity? (International Journal of Obesity, 2025)
Frequently asked questions
At which timepoints did the phase 2 obesity trial measure body weight?▾
The study set percentage change in body weight at week 24 as its primary endpoint and percentage change at week 48 as a key secondary endpoint in adults with obesity or overweight plus a weight-related condition (PMID 37366315). Researchers reported mean changes at both visits, including −24.2% in the 12 mg group and −2.1% with placebo at week 48 (PMID 37366315).
How long did the type 2 diabetes trial run?▾
That randomised, double-blind, placebo- and active-controlled phase 2 trial assessed HbA1c change from baseline at week 24 as its primary endpoint, with further endpoints measured through week 36 and dulaglutide 1.5 mg as the active comparator (PMID 37385280). Researchers reported dose-dependent reductions in HbA1c and body weight in the retatrutide groups over that period (PMID 37385280).
Has any study followed participants beyond 48 weeks?▾
No published retatrutide randomised trial has reported efficacy endpoints past 48 weeks; the obesity trial ended at week 48 (PMID 37366315) and the diabetes trial at week 36 (PMID 37385280). Longer registrational trials in obesity, obstructive sleep apnoea and knee osteoarthritis have had their rationale and design published, but not their results (PMID 41090431).
What did studies report about body composition over time?▾
A substudy of the phase 2 type 2 diabetes trial used imaging to quantify body composition and reported reductions in fat mass alongside changes in lean tissue over the randomised treatment period (PMID 40609566). It included only the imaged subset of participants. A separate review discussed whether resistance exercise could influence lean-mass changes during incretin-based weight loss (PMID 38687506).
When did adverse events appear in the trials?▾
Researchers reported that gastrointestinal events — nausea, diarrhoea, vomiting and constipation — were the most common, mostly mild to moderate, dose-related, and partly mitigated by lower starting doses with escalation (PMID 37366315). The diabetes trial reported a similar dose-dependent gastrointestinal pattern (PMID 37385280), and pooled randomised data reported more gastrointestinal events than placebo (PMID 40291085).
Do any head-to-head trials compare retatrutide timelines with other agents?▾
No published head-to-head randomised trial with matched timepoints exists. Comparative statements come from indirect evidence, such as a Bayesian network meta-analysis ranking GLP-1 receptor agonists, dual agonists and retatrutide for weight loss in adults with overweight or obesity (PMID 40685589). Class reviews summarise efficacy and safety across differing trial durations (PMID 38843460).
What is retatrutide's development status in the literature?▾
Reviews published through 2025 described retatrutide as an investigational triple GIP, GLP-1 and glucagon receptor agonist whose place depends on ongoing registrational trials (PMID 40563436), and a pipeline review situated triple agonists among candidate obesity medications still under study (PMID 38302593). The TRIUMPH programme design has been published without outcome data (PMID 41090431).
Track it. Calculate it. Actually understand it.
References
This page summarises published research for education — it is not medical advice, and nothing here is a recommendation to use, purchase, or dose any substance. Study parameters described are what researchers reported, not instructions. Consult a qualified clinician before any health decision.