If I Stop a GLP-1, Will I Gain the Weight Back?
Quick Answer
Most of it, usually, and not because of willpower.
But not all of it. This is one of the better-studied questions in obesity medicine, because three trials were designed specifically to answer it, two of them by randomizing people to continue or stop after they had already lost the weight.
What the Withdrawal Trials Show
The STEP 1 extension followed people for a year after semaglutide and lifestyle support were both stopped. Average weight loss at 68 weeks had been 17.3 percent. By week 120, participants had regained 11.6 percentage points of that, leaving them 5.6 percent below where they started. The cardiometabolic improvements, blood pressure and lipids among them, drifted back toward baseline alongside the weight. Two details matter for reading that number honestly: the lifestyle intervention was withdrawn at the same time as the drug, and the extension was an exploratory analysis in a 327-person subset rather than the full trial.
STEP 4 asked the question more cleanly. Everyone took semaglutide for 20 weeks and lost about 10.6 percent. They were then randomized either to continue or to switch to placebo, with lifestyle support kept in place for both groups. Over the next 48 weeks the group that continued lost a further 7.9 percent. The group switched to placebo gained 6.9 percent. That is a 14.8 percentage point gap created by nothing except whether the medication continued.
SURMOUNT-4 did the same with tirzepatide, and the numbers are larger. After 36 weeks of open-label tirzepatide, average weight reduction was 20.9 percent. Participants were then randomized to continue or to placebo for 52 weeks. Those continuing lost another 5.5 percent. Those switched to placebo regained 14.0 percent. Of the people who stayed on treatment, 89.5 percent held onto at least 80 percent of what they had lost. On placebo, 16.6 percent did.
Why It Comes Back
Appetite returns toward baseline when the medication stops, but metabolism does not return to where it started. Part of what was lost during treatment is lean tissue, and the active thyroid signal that sets metabolic rate can shift downward during the weight loss itself. The result is a body that is smaller and burning less than it was before, meeting an appetite that has gone back to normal.
The mechanism in full. Both of those shifts, and what can be built into a plan from the start to blunt them, are covered in The Weight Comes Back for Two Reasons Nobody Warns You About.
What Does Not Come Back
The trials do not show a complete reversal, and that distinction is worth holding onto. STEP 1 participants were still 5.6 percent below baseline two years in, after a full year off treatment. SURMOUNT-4 participants switched to placebo, having regained 14 percent, were still 9.9 percent below where they started at week 88. Regain is substantial and it is the expected course, but partial retention is the consistent finding, not a return to square one.
How to Read All of This
The conclusion the STEP 1 investigators drew from their own data is that these findings confirm the chronicity of obesity, and that ongoing treatment is required to maintain the improvements. That is the same logic applied to blood pressure or thyroid replacement, where nobody treats the return of the problem after stopping as evidence the treatment failed. What these trials establish is that a GLP-1 is a treatment for an ongoing condition rather than a course to be finished, and that the question worth thinking through before starting is not whether it will work but what the plan looks like on the other side of the weight loss.
The full trial data on each drug. Semaglutide, Tirzepatide, and Liraglutide, each graded study by study.
Thinking about starting a GLP-1, or already on one and wondering what happens next? Let's talk it through at your next visit.
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Dr. Darrell Wilcox · @wellnessdoc_4everyoung on Instagram
References
- Wilding JPH, Batterham RL, Davies M, et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: The STEP 1 trial extension. Diabetes Obes Metab. 2022;24(8):1553-1564. doi:10.1111/dom.14725
- Rubino D, Abrahamsson N, Davies M, et al. Effect of Continued Weekly Subcutaneous Semaglutide vs Placebo on Weight Loss Maintenance in Adults With Overweight or Obesity: The STEP 4 Randomized Clinical Trial. JAMA. 2021;325(14):1414-1425. doi:10.1001/jama.2021.3224
- Aronne LJ, Sattar N, Horn DB, et al. Continued Treatment With Tirzepatide for Maintenance of Weight Reduction in Adults With Obesity: The SURMOUNT-4 Randomized Clinical Trial. JAMA. 2024;331(1):38-48. doi:10.1001/jama.2023.24945
This content is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. GLP-1 receptor agonists are prescription medications with their own indications, contraindications, and monitoring requirements, and any decision to start, continue, or stop treatment should be made with your own physician. Individual results differ from trial averages. Dr. Wilcox is licensed to practice in multiple states. See About for current licensure.