How much weight can I lose on retatrutide?
On retatrutide's 12 mg dose, Phase 2 showed ~24% weight loss at 48 weeks. Here's the dose-response table, what Phase 3 confirmed, and honest caveats.
Updated May 18, 2026 · 3 min read
The best available data shows approximately 17–24% weight loss at 48 weeks, depending on dose — with the 24% figure coming from the highest dose studied (12 mg weekly) in Phase 2. Phase 3 TRIUMPH-1 data confirmed the signal holds at scale. But the range matters more than the headline number: most people in clinical practice will land at a lower dose, and individual response varies significantly.
The Dose-Response Table
Retatrutide weight loss isn't a flat number — it scales substantially with dose. From the Phase 2 trial (Jastreboff et al., NEJM, 2023):
| Dose | Mean weight loss at 48 weeks |
|---|---|
| Placebo | ~2% |
| 1 mg | ~9% |
| 4 mg | ~17% |
| 8 mg | ~23% |
| 12 mg | ~24% |
The 12 mg dose is where the 24% headline comes from. Notice that 8 mg produces nearly the same result (~23%) — the curve flattens considerably at the top. In practice, many people will titrate to 8 mg based on tolerability, and the efficacy difference vs. 12 mg is modest.
The 4 mg figure (~17%) is also notable: it already exceeds semaglutide's landmark STEP-1 result (~15% at 2.4 mg, 68 weeks), and does so in a shorter timeframe.
What the TRIUMPH-1 Phase 3 Data Confirmed
The Phase 2 trial enrolled ~338 participants across five dose arms — a relatively small sample. The key question was whether the results would hold in a larger, more representative Phase 3 population.
TRIUMPH-1 topline data confirmed that the Phase 2 signal was not a Phase 2 artifact. Weight loss at the highest doses remained in the 22–24% range. The full Phase 3 publication will add body composition data, longer-term maintenance, and cleaner responder-rate breakdowns, but the headline efficacy numbers were validated.
How It Compares to Other GLP-1 Drugs
For context against the drugs most people are currently using:
| Drug | Trial | Max dose | Duration | Mean weight loss |
|---|---|---|---|---|
| Semaglutide (Wegovy) | STEP-1 | 2.4 mg | 68 weeks | ~15% |
| Tirzepatide (Zepbound) | SURMOUNT-1 | 15 mg | 72 weeks | ~21% |
| Retatrutide | Phase 2 | 12 mg | 48 weeks | ~24% |
Cross-trial comparisons have real limitations — different populations, different durations, different monitoring intensity. The retatrutide advantage over tirzepatide is likely in the 3–5 percentage point range based on matched-population analysis, but a head-to-head randomized trial hasn't been run.
What "Average" Means for You
The 24% figure is a mean — the average across all participants at that dose. Some did better, some did less. A few practical implications:
- Roughly 90% of participants in the high-dose arms lost at least 5% of body weight — meaning very few complete non-responders
- Roughly 60–65% lost at least 20% — a substantially higher share than what semaglutide or tirzepatide produce
- About 10–15% lost less than 5%, even at the highest doses
Your individual result depends on factors that aren't perfectly predicted by dose: baseline metabolic health, whether you have type 2 diabetes (which reduces weight loss on GLP-1 drugs), adherence, protein intake, and individual variation in receptor response.
The Honest Caveat
Retatrutide is not yet FDA-approved. The 24% figure comes from Phase 2 (small sample, high monitoring intensity, tight selection). Phase 3 confirms it broadly, but real-world numbers — in a less-selected population, with typical clinical support rather than trial infrastructure — tend to be more modest than trial numbers for any drug.
The right frame: expect meaningful weight loss, with 15–20% a realistic target for most people at maintained doses, with some achieving more and some less.
See our TRIUMPH-1 deep dive for the full trial breakdown, and our retatrutide vs tirzepatide comparison for the cross-drug analysis.