STEP 1: what the semaglutide obesity trial actually randomized

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STEP 1: what the semaglutide obesity trial actually randomized

Wilding and colleagues assigned 1,961 adults to once-weekly semaglutide 2.4 mg or placebo for 68 weeks, on top of lifestyle intervention.

August 28, 2026 1 min read Phase 3 trial Semaglutide

STEP 1 is the trial people mean when they cite semaglutide for weight loss, and it is easy to blur. Wilding and colleagues published it in the New England Journal of Medicine in 2021. Adults with overweight or obesity, without diabetes, were randomized to once-weekly semaglutide 2.4 mg or placebo for 68 weeks, with a lifestyle intervention in both groups. The reported mean weight change was about 14.9 percent with semaglutide and 2.4 percent with placebo.

Read the population before the percentage

The percentage is an average in that sample, at that dose, over that duration. It is not a promise for a different dose, a shorter course, or a compounded product of uncertain identity. Gastrointestinal effects were the familiar incretin pattern and the main reason people stopped treatment. The paper’s tables, not a social-media recap, are the place to see discontinuation and the secondary endpoints.

This was an approved-drug program

Semaglutide 2.4 mg later reached the market as Wegovy under an FDA label that states the indication, dose escalation, and warnings. STEP 1 studied that pharmaceutical product. It did not study research-vial shorthand such as “GLP1-SG,” and a weight-loss percentage from STEP 1 does not transfer to a vial that was never in the trial.

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