STEP 1 — once-weekly semaglutide in adults with overweight or obesity
New England Journal of Medicine / PubMed
TL;DR
In STEP 1, 1,961 adults receiving weekly semaglutide 2.4 mg plus lifestyle intervention lost an average 14.9% of body weight over 68 weeks versus 2.4% with placebo.
Phase 3 · randomized · double-blind · placebo-controlled · 1,961 adults
What was studied
The question.
Whether once-weekly semaglutide 2.4 mg could produce clinically meaningful weight loss in adults with overweight or obesity who did not have diabetes.
How it was conducted
The study design.
Participants were randomized 2:1 to semaglutide 2.4 mg or placebo for 68 weeks. Both groups received lifestyle intervention. The main outcomes were percentage weight change and the proportion losing at least 5% of baseline weight.
What it found
Did it actually work?
- Mean weight change was -14.9% with semaglutide versus -2.4% with placebo.
- The trial demonstrated a large clinically meaningful treatment effect on weight loss.
Why it matters
How to read this result.
STEP 1 is a cornerstone study behind semaglutide's modern obesity evidence base and shows the scale of effect achievable with GLP-1 therapy in a large controlled trial.
Keep in mind
What the study does not prove.
- The population excluded people with diabetes.
- Participants received lifestyle intervention as well as medication or placebo.
- Trial results do not determine the appropriate treatment for an individual patient.
Original source
Want to read the original?
We summarize the study here first. The original source is there when you want the full methods, statistics, tables and author discussion.
Open ClinicalTrials.gov record