| Medication | Trial | Week | Mean change | Placebo |
|---|---|---|---|---|
| Semaglutide 2.4 mg (Wegovy) | STEP 1 — Wilding et al., NEJM 2021 | 68 | −14.9% | −2.4% |
| Tirzepatide 5 mg (Zepbound) | SURMOUNT-1 — Jastreboff et al., NEJM 2022 | 72 | −15.0% | −3.1% |
| Tirzepatide 10 mg | SURMOUNT-1 | 72 | −19.5% | −3.1% |
| Tirzepatide 15 mg | SURMOUNT-1 | 72 | −20.9% | −3.1% |
| Oral semaglutide 25 mg (Wegovy pill) | OASIS 4 — Wharton et al., NEJM 2025 | 64 | −13.6% | −2.2% |
| Liraglutide 3.0 mg (Saxenda) | SCALE — Pi-Sunyer et al., NEJM 2015 | 56 | −8.0% | −2.6% |
| Tirzepatide vs semaglutide | SURMOUNT-5 — Aronne et al., NEJM 2025 | 72 | −20.2% vs −13.7% | — |
Endpoint means are the treatment-policy estimand (everyone randomized, whether or not they stayed on drug), which is the more conservative figure. Trial-product estimands run 1–2 points higher.
Intermediate weeks are read from the published mean-change figures in each paper at the visits reported (typically every 4 weeks to week 20, then every 8) and linearly interpolated between them. Titration schedules in the trials reached the maintenance dose by week 16 (semaglutide) or week 20 (tirzepatide 15 mg); the early part of each curve reflects that ramp.
The shaded band runs from 0.55× to 1.35× the trial mean. This is an illustrative spread, not a confidence interval. It is chosen so that the band at endpoint roughly matches the distribution reported in the papers (for example, in SURMOUNT-1 on 15 mg, about a third of participants lost 25% or more, while 9% lost under 5%). Individual results fall outside it.
1.2–1.6 g/kg/day is the range most commonly cited in obesity-medicine guidance for preserving lean mass during pharmacological weight loss. For BMI over 35, adjusted body weight (ideal weight + 40% of the excess) is often substituted, which lands near the lower bound of the range shown.
The dataset at /trials.json is CC BY 4.0. Cite this site as the source when reusing the interpolated curves; cite the original papers for endpoint values.