Why weight returns after Mounjaro
Two withdrawal trials show what happens to weight after stopping tirzepatide or semaglutide, and what a Seoul obesity physician suggests doing with the treatment window.
September 18, 2026
It is the question people ask most often in a first consultation about obesity medication. If I stop, do I gain it back? The answer is uncomfortable but simple. Most people do.
This is not a guess. It comes from a trial the manufacturer designed to test exactly that. Participants took tirzepatide, sold as Mounjaro, for 36 weeks. Then half continued and half were switched to placebo. The trial is called SURMOUNT-4, and what happened over the following 52 weeks is the answer to the question.
| Week 36 to week 88 | Weight change |
|---|---|
| Continued tirzepatide | 5.5% further loss |
| Switched to placebo | 14% regained |
The split shows up another way too. By week 88, 89.5 percent of those who stayed on the drug had kept at least 80 percent of their earlier weight loss. Among those switched to placebo, 16.6 percent had.
Semaglutide, sold as Wegovy, behaves the same way. In the extension of the STEP-1 trial, participants regained two thirds of their lost weight in the year after stopping. They had spent 68 weeks losing it. Measured from the very beginning to week 120, the net loss that remained was 5.6 percent.
Read on their own, these numbers point one direction. They suggest the medication is something you stay on indefinitely.
A different angle
In a short video, Dr. Kang Min-gu approaches the question from a different side. His point is that weight returns because the way you live on the medication and the way you live off it are two different things. The drug leaving your system is not the whole explanation.
What he draws attention to is the window itself. While you are taking semaglutide or tirzepatide, changing how you eat becomes easier, because the drug produces satiety and satiety makes a plan possible to follow. He suggests repeating that pattern until it becomes habit, and only then, gradually, increasing portions again.
This treats the medication as something that creates the conditions under which willpower works, rather than as a replacement for it. Keeping to a meal plan while hungry and keeping to one while full are not the same task. The drug supplies the second condition. What you practice while it lasts is what you are left with afterward.
Where this needs qualifying
Some honesty is required here. Clinical data does not promise that building habits lets you maintain the loss without the drug. If anything it points the other way.
In both trials cited above, participants did not simply receive an injection. They also received diet and exercise counselling. They regained the weight anyway. Lifestyle support was part of the protocol and it was not enough on its own. This is why obesity medicine increasingly treats obesity as a chronic condition to be managed continuously, in the same way as hypertension or type 2 diabetes. Nobody stops taking blood pressure medication because their blood pressure has been normal for a few months.
That does not make the argument about habits empty. The two are not in competition. Whether to continue, taper or stop is a decision made with the physician managing your care, and what widens the range of workable options is what you have built in the meantime. It is entirely plausible that the difference between regaining 14 percent and regaining less is decided there. What does not yet exist, as far as we could find, is a trial that compares the two directly and puts a number on it.
Questions worth asking
How long is this intended to continue? A course of several months and an indefinite prescription are different commitments, financially and otherwise. A clinic that avoids the question is telling you something.
What does stopping look like? Ask whether there is a tapering process, and what happens during it. A prescription written without any plan for coming off it produces the numbers above.
Who is writing the prescription? These drugs interact with a history of pancreatitis, with a family history of medullary thyroid cancer, and with other medications. A physician trained in metabolic disease evaluates that differently from one who is not.
Disclosure. This magazine is published by Team Sinsa, which handles marketing for BalanceLab. This is an informational column, not an independent review or ranking.
References: Aronne LJ 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. Wilding JPH et al., Weight regain and cardiometabolic effects after withdrawal of semaglutide: The STEP 1 trial extension, Diabetes, Obesity and Metabolism, 2022;24(8):1553-1564.
Dr. Kang's remarks are summarised from a video published by BalanceLab at https://youtube.com/shorts/xGJuamUaX6M . The photograph is BalanceLab material. This is general information and does not replace individual medical care.
