What Happens When You Stop Semaglutide? The STEP 4 Weight Regain Study

This was a randomized, double-blind, phase 3a withdrawal trial (STEP 4) conducted at 73 sites in 10 countries. All 902 participants first received semaglutide 2.4 mg weekly for 20 weeks (16 weeks dose escalation + 4 weeks maintenance). Then 803 participants who reached the maintenance dose were randomized 2:1 to either continue semaglutide (n=535) or switch to placebo (n=268) for 48 more weeks. Both groups received lifestyle intervention throughout. Primary endpoint was percent body weight change from week 20 to week 68.

This is one of the most important studies in the semaglutide weight loss program because it definitively answers the question: what happens when you stop? The answer is clear — weight comes back. This has major implications for how patients and doctors approach GLP-1 therapy, confirming that semaglutide for obesity is likely a long-term or lifelong treatment rather than a short-term intervention. It also demonstrates that continuing treatment produces ongoing benefits beyond just weight loss.

STEP 4 was a pivotal study in reshaping how the medical community and public think about GLP-1 weight loss drugs. By showing that weight regain begins almost immediately after stopping semaglutide, it established that obesity treatment with these drugs requires ongoing use — similar to blood pressure or cholesterol medications. This finding has fueled the debate about long-term costs, insurance coverage, and whether lifelong injectable therapy is sustainable for the millions of people with obesity.

The study excluded people with diabetes, so results may not fully apply to that population. The 20-week run-in means participants who couldn't tolerate semaglutide were already filtered out before randomization. The placebo group's weight regain demonstrates drug dependence for weight maintenance, raising questions about lifelong treatment costs and sustainability.