Weight regain after stopping treatment: why it happens and how it is managed

You have reached your target, you stop the medication and, a few months later, the scales start creeping up again. It is one of the most frustrating scenes in the whole process, and also one of the least well understood. Regaining some weight after stopping treatment with a GLP-1 receptor agonist is not a sign that you have done anything wrong: it is what the body tends to do once the drug is no longer there. In this article we explain why it happens, what the evidence actually says and how it is managed, without drama and without promises.

Why weight comes back when you stop the drug

The starting point is uncomfortable but important: obesity is a chronic, relapsing disease. Drugs such as semaglutide or tirzepatide control weight while they are being given, but they do not resolve the underlying condition. If you want to understand how they work while you are taking them, we explain it in detail in our guide on what GLP-1 is and how it works in obesity.

When treatment is withdrawn, the appetite-suppressing and satiating effect disappears, and the physiological mechanisms the body uses to defend its weight come back into play: increased appetite, adaptation of energy expenditure and the hormonal responses that push you to eat more. That is why weight regain is an expected physiological phenomenon, not a matter of discipline or willpower. The body simply goes back to doing what it did before the medication put the brakes on.

What the evidence says

It is worth being precise with the figures here, because each piece of data comes from a different trial, with a different drug and a different design. They are not interchangeable.

Semaglutide: the STEP 1 trial follow-up

In the STEP 1 trial extension, participants treated with semaglutide 2.4 mg weekly (alongside a lifestyle intervention) had lost an average of 17.3% of their weight by week 68. After stopping the drug, by around week 120 they had regained 11.6 percentage points, that is, roughly two thirds of what they had lost. In the placebo group the change was just 1.9 percentage points. One relevant nuance: along with the weight, the cardiometabolic improvements that had been achieved, such as blood pressure, HbA1c and the lipid profile, also largely reverted towards baseline values.

Tirzepatide: the SURMOUNT-4 trial

The SURMOUNT-4 trial tackled the same question with tirzepatide and did so directly: after an open-label phase, some patients continued on the drug and others switched to placebo. Over the following 52 weeks, those who switched to placebo regained 14.0% of their weight, while those who stayed on tirzepatide lost a further 5.5%, a difference of 19.4 percentage points between groups. Looking at the whole picture (from week 0 to week 88), the mean weight loss was 25.3% with continued tirzepatide versus 9.9% with placebo. And one figure sums up the maintenance question rather well: 89.5% of those who continued kept at least 80% of their initial weight loss, compared with only 16.6% of those who switched to placebo.

Read together, the two trials tell a consistent story: what sustains the result in the long term is maintenance treatment. If you are interested in the differences between these drugs, we compare them in our article on Mounjaro and Ozempic.

Common myths, debunked

"You put it all back on and end up where you started." That is not what the data show. In STEP 1, about two thirds of the weight lost came back, not 100%, and in SURMOUNT-4 patients still had a net loss compared with their starting weight. The size of the regain depends on the drug and on how much time has passed, but going back to square one is not the usual finding in these studies.

"There is a rebound effect that leaves you heavier than before you started." The trials do not show over-regain above baseline weight. Weight does come back, yes, but there is no documented evidence of people ending up weighing more than they did when treatment began.

"If you regain weight, it means you have let things slide." False. Regain is explained by physiological mechanisms (appetite, hormones and energy expenditure), not by personal weakness. Framing it as a failure of willpower is not only unfair, it also distracts from what is actually going on.

"It is impossible to maintain weight without the drug." That is not accurate either. Some patients keep part of the loss, and a structured lifestyle intervention helps. The honest message is not that it is impossible, but that sustaining it is hard, and that stopping treatment is not without consequences: along with the weight, the cardiometabolic improvements may also reverse.

Where things stand in Spain

As of July 2026, semaglutide is authorised by the EMA and available in Spanish pharmacies as Wegovy (semaglutide 2.4 mg, indicated for obesity or overweight with a comorbidity, marketed since May 2024), Ozempic (indicated for type 2 diabetes) and Rybelsus (oral). Tirzepatide is authorised as Mounjaro. All of them require a doctor's prescription.

The key point, and it is a financial one, is that none of these drugs is funded by the Spanish National Health System for weight management: in 2025 the Spanish Ministry of Health rejected public funding for Wegovy (on three separate occasions) and also decided not to fund Mounjaro for weight loss, citing the budget impact and the sustainability of the system. Patients pay for them privately; the press has quoted ranges of around 180 to 292 euros a month for Wegovy following the March 2026 price cut, and around 200 to more than 400 euros a month for Mounjaro. Talks between Novo Nordisk and the Ministry of Health about possible future funding remained open. We break down the costs in our guide to the price of medical weight loss treatment in Spain.

This matters precisely because of what we have just seen: if the result is sustained above all by continued treatment, planning cannot stop at the months of active weight loss, it has to take the medium and long term into account.

So what should you do?

The available evidence (trials such as STEP 4 or SURMOUNT-4) points towards understanding obesity as a chronic disease that usually requires ongoing management, rather than towards withdrawing the drug as a standard step once the target has been reached. That said, there is no single answer: how long to continue, how to approach a possible withdrawal, how much weight to give to the lifestyle intervention and how to monitor cardiometabolic parameters are all decisions that depend on your history, your goals and your particular situation.

If you are on treatment, thinking about stopping or trying to keep off the weight you have already lost, what makes the difference is having a medical team that reviews your case and supports you in the decision — with sound judgement, not fear. Medical weight-loss treatment is now available in Spain, with prior assessment, a prescription where appropriate from a registered doctor and ongoing follow-up from the medical team. You can check whether you are eligible in 30 seconds.