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What the weight-loss trials found

8 trials · 15,462 people

Everyone asks the same question: how much weight do you lose? The trials answer it, and the answer is not the one in the advertising. People in the placebo group lose weight too — so the drug's real effect is the difference between the two bars, not the height of one.

  1. Retatrutide

    TRIUMPH-1 · 2026 · ELI LILLY

    Treatment-19 % … -28.3 %
    placebo-2.2 %
    N
    2 339
    WEEKS
    80

    Topline figures from a press release. Not published in a peer-reviewed journal, and therefore not comparable with the rows above.

    [source] TRIUMPH-1, Eli Lilly 2026
  2. Retatrutide

    FAS 2 · 2023 · NEJM

    Treatment-8.7 % … -24.2 %
    placebo-2.1 %
    N
    338
    WEEKS
    48
  3. Tirzepatide

    SURMOUNT-1 · 2022 · NEJM

    Treatment-15 % … -20.9 %
    placebo-3.1 %
    N
    2 539
    WEEKS
    72

    The range is three separate dose arms, not an uncertainty interval.

    [source] SURMOUNT-1, NEJM 2022
  4. Cagrilintide

    REDEFINE 1 · 2025 · NEJM

    Treatment-20.4 %
    placebo-3 %
    N
    3 417
    WEEKS
    68

    This result is kagrilintide COMBINED with semaglutide. The monotherapy arm (302 participants) has no reported result.

    [source] REDEFINE 1, NEJM 2025
  5. Tirzepatide

    SURMOUNT-5 · 2025 · NEJM

    Treatment-20.2 %
    semaglutide-13.7 %
    N
    751
    WEEKS
    72

    The comparator is semaglutide, not placebo — hence the small gap.

    [source] SURMOUNT-5, NEJM 2025
  6. Semaglutide

    STEP 1 · 2021 · NEJM

    Treatment-14.9 %
    placebo-2.4 %
    N
    1 961
    WEEKS
    68

    50.5% reached at least 15% weight loss, against 4.9% on placebo.

    [source] STEP 1, NEJM 2021
  7. Survodutide

    FAS 2 · 2024 · LANCET D&E

    Treatment-6.2 % … -14.9 %
    placebo-2.8 %
    N
    386
    WEEKS
    46

    Only 233 of 386 participants (60.4%) completed the treatment period.

    [source] Fas 2, Lancet D&E 2024
  8. Liraglutide

    SCALE · 2015 · NEJM

    Treatment-8.4 kg
    placebo-2.8 kg
    N
    3 731
    WEEKS
    56

    Reported in kilograms rather than percent, and therefore not directly comparable with the rows above.

    [source] SCALE, NEJM 2015

Both groups are drawn, because the drug's real effect is the gap between them — not the height of the whole bar. These are group averages from the cited trials and say nothing about what any one person would lose.