What the Published Data Actually Shows
The Phase 2 figures in the table below come from the published randomised controlled trial (Jastreboff et al., New England Journal of Medicine, 2023), which tested four once-weekly dose cohorts against placebo over 48 weeks. This page summarises those results by cohort and timepoint, and sets out the limits of that historical dataset alongside a dated update on the Phase 3 programme and is not TGA-approved for therapeutic use.
For the full mechanism of action and Phase 3 trial programme, see the Retatrutide Research Overview. This page focuses specifically on the weight-reduction outcome data.
Results by Dose Cohort
The Phase 2 trial studied four once-weekly dose cohorts (1mg, 4mg, 8mg, 12mg) plus placebo. Reported mean body weight reduction from baseline was dose-dependent at every measured timepoint.
| Dose Cohort | Mean Reduction at 24 Weeks | Mean Reduction at 48 Weeks |
|---|---|---|
| 1mg | 7.2% | 8.7% |
| 4mg (combined) | 12.9% | 17.1% |
| 8mg (combined) | 17.3% | 22.8% |
| 12mg (highest) | 17.5% | 24.2% |
| Placebo | 1.6% | 2.1% |
Source: Jastreboff et al., NEJM 2023 (PMID 37366315). The table shows least-squares mean percentage reductions from baseline, not placebo-adjusted differences. The 4mg and 8mg values combine the starting-dose groups. Study cohorts are not personal-use instructions.
Timeline of Measured Change
In the highest-dose cohort, dose-dependent separation from placebo was already measurable by the 24-week mark, with continued mean reduction reported through the 48-week endpoint, the longest duration covered in the published Phase 2 data. Lilly presented TRIUMPH-1 Phase 3 results at the ADA Scientific Sessions on 6 June 2026, with an 80-week primary assessment and a 104-week extension. These findings are separate from the 2023 Phase 2 study and do not establish equivalence of separately supplied research materials. Source: Lilly: TRIUMPH-1, ADA 2026.
Weight reduction did not plateau by week 48 in the highest-dose cohort, which is part of the rationale for the longer Phase 3 observation window.
Interpreting the study results
Interpret the result within its study population, follow-up period and analysis method. The table below summarises Retatrutide research; it does not establish effectiveness of catalogue material.
| Compound | Receptor Targets | Reported Highest-Dose Reduction |
|---|---|---|
| Retatrutide | GIP/GLP-1/Glucagon | 24.2% (48 weeks) |
What the Data Doesn't Establish
- Outcomes beyond 48 weeks cannot be inferred from this Phase 2 table; the separate TRIUMPH-1 Phase 3 presentation reports longer follow-up.
- Real-world variability outside controlled trial conditions and defined cohort protocols.
- A reliable ranking against other interventions cannot be inferred by comparing percentages from separate trials with different populations and durations.
- Any therapeutic claim — retatrutide is not TGA-approved and is supplied by Eternal Peptides Wholesale for qualified laboratory research use only, not for human consumption.
Sourcing Retatrutide for Research
Eternal Peptides Wholesale supplies Retatrutide as RT10 (10mg, box of 10 vials, $544.50) and RT20 (20mg, box of 10 vials, $891.00), with Janoshik-verified batch testing published on each product page before purchase.
View Products & PricingFrequently Asked Questions
What weight loss results has retatrutide shown in trials? +
Phase 2 data published in The New England Journal of Medicine (Jastreboff et al., 2023) reported mean body weight reductions of 17.5% at 24 weeks and up to 24.2% at 48 weeks in the highest dose cohort (12mg once weekly). Results were dose-dependent across the four cohorts studied. These figures describe the 2023 Phase 2 study. TRIUMPH-1 Phase 3 results were presented in June 2026. For research use only.
How long does it take to see results in retatrutide research? +
In the published Phase 2 trial, dose-dependent weight reduction was already measurable at 24 weeks and continued through 48 weeks, the longest duration reported in that study. The Phase 2 study ended at 48 weeks. TRIUMPH-1 subsequently reported an 80-week primary assessment and a 104-week extension in June 2026. For research use only, not applicable to individual outcomes.
Do results vary by dose? +
Yes. The Phase 2 trial tested four once-weekly dose cohorts (1mg, 4mg, 8mg, 12mg). Reported mean weight reduction increased with dose, from single-digit percentages in the lowest cohort to approximately 24% in the highest cohort at 48 weeks. This dose-response relationship is a key variable in study design. For research use only.
What don't the published results tell us? +
The cited phase 2 study used defined cohorts and a 48-week endpoint. It does not establish longer-term outcomes beyond that window or real-world outcomes outside controlled trial conditions. Later phase 3 findings must be evaluated separately. For research use only.
Where can researchers source retatrutide for studies in Australia? +
Eternal Peptides Wholesale supplies Retatrutide (RT10, 10mg and RT20, 20mg, both boxes of 10 vials) with Janoshik-verified batch testing published on every product page. For qualified laboratory research use only, not for human therapeutic use.