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Calculator preview · all three medications, 100 kg start

Semaglutide (STEP 1: Effect and Safety of Semaglutide 2.4 mg Once-weekly in Subjects With Overweight or Obesity (NEJM 2021)): week 68 treatment 85.1 kg, placebo 97.6. Tirzepatide (SURMOUNT-1: Efficacy and Safety of Tirzepatide Once Weekly in Participants Without Type 2 Diabetes Who Have Obesity or Are Overweight With Weight-Related Comorbidities (NEJM 2022)): week 72 treatment 79.1 kg, placebo 96.9. Retatrutide (Retatrutide Phase 2 Obesity Trial (NEJM 2023; registry title: A Study of LY3437943 in Participants Who Have Obesity or Are Overweight)): week 24 treatment 82.5 kg, placebo 98.4; week 48 treatment 75.8 kg, placebo 97.9wk 0wk 12wk 24wk 36wk 48wk 60wk 72Semaglutide -14.9%Tirzepatide -20.9%Retatrutide -24.2%
Semaglutide (STEP 1: Effect and Safety of Semaglutide 2.4 mg Once-weekly in Subjects With Overweight or Obesity (NEJM 2021))Tirzepatide (SURMOUNT-1: Efficacy and Safety of Tirzepatide Once Weekly in Participants Without Type 2 Diabetes Who Have Obesity or Are Overweight With Weight-Related Comorbidities (NEJM 2022))Retatrutide (Retatrutide Phase 2 Obesity Trial (NEJM 2023; registry title: A Study of LY3437943 in Participants Who Have Obesity or Are Overweight))

Markers are the published measurements. Straight lines between markers — and the dashed segment from baseline — are visual connectors, not measured trajectories. Studies ran for different durations (Semaglutide 68 wk, Tirzepatide 72 wk, Retatrutide 48 wk), used different doses and populations, and are not head-to-head — do not read this as a direct efficacy ranking.

Comparison chart data
StudyWeekTreatment avg (kg)ChangePlacebo avg
Semaglutide6885.1-14.9%97.6
Tirzepatide7279.1-20.9%96.9
Retatrutide2482.5-17.5%98.4
Retatrutide4875.8-24.2%97.9

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The medications

FDA-approved

Semaglutide

Approved for chronic weight management.

FDA-approved

Tirzepatide

Approved for chronic weight management.

Investigational

Retatrutide

Not FDA-approved as of the October 2026 content review.

Separate studies are never head-to-head comparisons.

Latest research

Retatrutide phase 2: what the 2023 NEJM trial did and didn't show

A plain-language reading of the 48-week phase 2 obesity trial of an investigational triple-hormone receptor agonist.

Reviewed 2026-10-11

How to read weight-loss trial numbers without being misled

Means, placebo adjustment, estimands, and why a trial average is not your personal forecast.

Reviewed 2026-10-11

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Content review 2026-10-11