The short answer
In STEP 1, weekly semaglutide plus lifestyle support produced substantially greater average weight loss than placebo plus the same support.
The comparison
The trial randomly assigned 1,961 adults with overweight or obesity, without diabetes, to semaglutide 2.4 mg or placebo for 68 weeks. Neither participants nor investigators knew the assignment.
Average weight change was −14.9% with semaglutide and −2.4% with placebo. The main analysis assessed treatment assignment even if participants stopped treatment or needed another intervention.
Percent of starting weight
Original chart based on the study. Values are reported group averages.
| Group or measure | Average result |
|---|---|
| Semaglutide 2.4 mg | −14.9% |
| Placebo | −2.4% |
Benefits and tolerability
Nausea and diarrhea were the most common adverse events with semaglutide, generally mild or moderate and temporary. Digestive events led 4.5% of semaglutide participants to discontinue, versus 0.8% with placebo.
An average is not a personal forecast. This trial also does not answer what happens after stopping. The STEP 1 extension follows that different question.
Sources
STEP 1, NEJM, 2021. Funded by Novo Nordisk. Study abstract · Paper.