Video brief · 2026-09-09
Semaglutide: What the Published Trials Actually Found
Two trials, the numbers, and the side effects. STEP 1 measured weight over 68 weeks. SELECT measured heart attacks and strokes over about three years. No hype, just what was reported.
Semaglutide is a prescription medication. The FDA approved it for type 2 diabetes in 2017 under the name Ozempic and for chronic weight management in 2021 as Wegovy. Everything below comes from the two largest published trials, not from marketing.
The weight trial was STEP 1, published in the New England Journal of Medicine in 2021. It enrolled 1,961 adults with overweight or obesity and no diabetes, and followed them for 68 weeks. The semaglutide group lost 14.9 percent of body weight on average. The placebo group lost 2.4 percent. Both groups received the same diet and exercise counselling, so the difference is attributable to the drug.
The heart trial was SELECT, same journal, 2023. It enrolled 17,604 adults who already had cardiovascular disease and a BMI of 27 or higher, again without diabetes. Over a mean follow-up of about 40 months, the combined rate of cardiovascular death, non-fatal heart attack and non-fatal stroke was 6.5 percent on semaglutide versus 8.0 percent on placebo, a 20 percent relative reduction. That result applies to people who already had heart disease; it has not been tested in people who do not.
The most common side effects in both trials were gastrointestinal: nausea, diarrhea and vomiting, mostly during the early dose-escalation period. It is prescribed and monitored by a physician.
That is the published record. Anything beyond it is a claim, not a finding. If any of this is relevant to your own health, the conversation belongs with a physician who can see your history.
Sources
- Wilding JPH et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1).
- N Engl J Med 2021;384:989-1002
- Lincoff AM et al. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes (SELECT).
- N Engl J Med 2023;389:2221-2232
Peptide Proof reports what studies found. We do not give medical advice, dosing guidance, or treatment recommendations.