Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1)

Researchers randomly assigned 1,961 adults with obesity or overweight and related health problems to weekly semaglutide injections or a placebo, an inactive injection. Everyone also received advice on eating and physical activity, and none had diabetes. After 68 weeks, people taking semaglutide lost about 15% of their body weight on average, compared with about 2% for the placebo group. Stomach-related side effects, including nausea, vomiting, diarrhea, and constipation, were common, and 4.5% stopped treatment because of side effects.

What this means for you: This is strong evidence that semaglutide can produce substantial weight loss while people take it. It is a prescription treatment with side effects and costs, and this study did not show that it helps people live longer.