What happens when you stop a GLP-1 like Wegovy or Mounjaro?

What happens to your weight when you stop?

In trials, most people regained much of the weight they had lost within a year of stopping. On average, they did not go all the way back to where they started.

The clearest test is a one-year follow-up of the main semaglutide trial (the STEP 1 extension). It followed 327 people for a year after treatment stopped: 228 had been on semaglutide 2.4 mg and the rest on a dummy injection.¹

So about two-thirds of the lost weight came back. For a 90 kg (14 st 2 lb) person, that means losing about 16 kg (2 st 7 lb), then regaining about 10 kg (1 st 8 lb).¹ About half the people (48%) were still at least 5% lighter than at the start.¹

Two more trials tested this differently. Everyone took the medicine first. Then, at random, some carried on and the rest were switched to a dummy injection without knowing. So the gap between the two groups shows what stopping does:

The kg figures are our arithmetic for one example person starting at 90 kg, using each trial's average percentages; real people varied a lot. In both trials about half the lost weight came back after switching. The trials also report regain of 6.9% (STEP 4) and 14.0% (SURMOUNT-4), but those are measured from the lower weight at the switch, so they look different.^2,3

Two 2026 reviews pooled many studies. A BMJ review of 37 studies (9,341 people) found weight came back at about 0.8 kg a month after semaglutide or tirzepatide.⁵ It projected a return to starting weight in about 1.5 years. That is an estimate: no study of these two drugs followed people for more than a year.⁵

A second review estimated that 60% of the lost weight returns in the first year. It predicted regain would level off at about 75%, not 100%.⁶ So the two reviews disagree: one projects a full return to starting weight, the other a partial one.^5,6 These are averages. In one tirzepatide analysis, 1 in 6 people regained less than a quarter of what they lost.⁴

What happens to blood sugar, blood pressure and cholesterol?

They tend to drift back towards where they were before treatment. The more weight comes back, the more they rise.

In STEP 1, blood pressure was back at its starting level a year after stopping. Average blood sugar (HbA1c, a 3-month sugar test) and cholesterol also rose again.¹

In the tirzepatide trial above (SURMOUNT-4), people who regained the most saw the biggest rises. Top (systolic) blood pressure went up by 7 to 10 points, depending on how much weight came back.⁴ People who kept most of the weight off kept some benefits, such as lower blood fats (triglycerides).⁴

The BMJ review projected that all these heart and sugar markers would be back at their starting levels within about 1.4 years.⁵

Why does the weight come back?

The medicine was holding your appetite down. When it wears off, hunger returns, and your body also pushes to regain lost weight.

Half of each semaglutide dose is still in the body after about a week. It stays in the blood for about 5 to 7 weeks after the last injection.¹³ As it goes, the feeling of fullness it gave goes too.

Losing weight by any route changes your hunger hormones. In one study of dieting, these changes and stronger hunger were still there a year later.⁸ The body acts as if it wants the weight back.

This is why experts now call obesity a long-term (chronic) condition, like high blood pressure. The WHO calls it "a chronic, relapsing disease requiring lifelong care".⁹ The STEP 1 authors said their results suggest ongoing treatment is needed to keep the benefits.¹

Regain is not a personal failure. The BMJ review found weight came back faster after medicines than after diet programmes alone, whatever the amount first lost.⁵

Can you take a lower dose, or taper off?

One good trial says a lower tirzepatide dose keeps most of the weight off. For semaglutide, and for tapering to zero, the evidence is thin.

One trial (SURMOUNT-MAINTAIN) took 378 US adults who had lost weight on tirzepatide 10 or 15 mg. They were split into 3 groups for a year: full dose, 5 mg, or a dummy injection.¹⁰

Most people in this trial were white women.¹⁰ So results may differ for men, and for people of other ethnic backgrounds. Eli Lilly, which makes tirzepatide, paid for it.¹⁰ Staying on a medicine also means staying with its side effects. In the semaglutide trial above (STEP 4), 42% of people who continued semaglutide had stomach side effects, vs 26% on a dummy injection.²

For semaglutide, no finished trial has tested a lower maintenance dose or a slow taper. The first randomised taper trial, in China, had not started recruiting as of October 2026.¹¹ In real life, many people already use lower doses. In one Danish GP practice, 40% of people still on semaglutide after a year took 1 mg or less.¹¹

The WHO's 2025 guideline names "maintenance and discontinuation" as areas where long-term data are limited.⁹ So a taper plan is your doctor's judgement, not a proven method.

What helps keep weight off?

Keeping up exercise and support with eating and habits help most. Nothing yet fully replaces the medicine.

A Danish trial gave 195 people who had just lost weight a year of supervised exercise, a GLP-1 medicine (liraglutide), both, or neither. Then all treatment stopped, and 109 of them were weighed again a year later.¹²

• Medicine plus exercise, against the medicine alone: about 2.5 kg less regain. That difference was small enough that it could have been chance.¹²
• Exercise alone, against the medicine alone: the medicine-only group regained about 6 kg more.¹²

So exercise during treatment looks helpful, but this one small trial can't prove how much it adds once you stop the medicine.

That exercise trial used liraglutide, an older daily GLP-1, and followed 109 people.¹² Protein and strength training to protect muscle are covered in Guide 8: Life on a GLP-1.

What does staying on it cost over years?

If you need it long term, the cost is long term too. On the NHS it's a prescription charge in England and free elsewhere in the UK. Privately, at the maker's list prices, 5 years of Mounjaro comes to about £11,700 at 5 mg and £21,450 at 15 mg, before VAT and the service's own charges.

These are examples, not a price list. A pen holds 4 weekly doses, so a year is 13 pens, or 13 prescription items.^16,22

Medicine only. Private services set their own prices and may add consultation, delivery or programme fees.

The NHS doesn't always cover the long term. NICE recommends Wegovy for weight in specialist services for a maximum of 2 years.¹⁵ If you're paying privately and hope to move to the NHS later, you can only do that if you meet the NHS criteria at the time you're assessed.²³

In one Danish GP practice, 38% had stopped semaglutide within a year, for all reasons.¹¹ Before you start, ask whether you could afford it for years, not months. Guide 7 explains how NHS and private routes charge.

When is stopping the right call?

Stopping is a reasonable choice in several situations. A medicine that harms you, isn't working, or can't be paid for is not worth staying on. These are the common reasons.

• Side effects you can't live with, or a serious one such as pancreatitis. Guide 5 lists the warning signs.
• Planning a pregnancy. The MHRA says to stop semaglutide at least 2 months, and tirzepatide at least 1 month, before trying to get pregnant.²¹ Semaglutide stays in the body a long time.¹³ The tirzepatide label warns it may harm an unborn baby.¹⁴
• An operation or sedation. These medicines slow the stomach. Rarely, people have breathed in stomach contents during anaesthesia.¹³ The labels say to tell your surgeon you take one. They say there isn't enough data to know if pausing it helps.^13,14
• It isn't working. See the NHS rules below.
• Cost, if paying privately is straining your budget.
• It was never the right medicine for you, for example taken to lose a few pounds before a holiday, or bought without a proper prescription. See Guide 4.

The NHS stopping rules

NICE, which sets NHS guidance in England, uses losing 5% of your starting weight as the test. For a 90 kg (14 st 2 lb) person, 5% is 4.5 kg, about 10 lb.

These rules are about whether a medicine is worth continuing. Falling short is not a personal failure, and your doctor can talk through other options.

How do you stop safely?

With your doctor, and with a plan for what comes next. Your weight, blood sugar and blood pressure will need watching for months.

The MHRA's advice is not to stop your treatment without first discussing it with your doctor.²¹ If you get it privately, NHS advice is that your private provider is the one to advise you on stopping or tapering safely.²³

If you have diabetes, stopping can push your HbA1c (a blood test of your average sugar over about 3 months) up.⁷ Your doctor may need to add or change another sugar medicine. Don't just stop and wait to see.

Keep the habits you built: regular exercise and the eating patterns that worked. They give you the best chance of holding on to some of the loss.¹²

What if you miss doses or can't get supply?

A short gap is usually fine. After a longer gap, ask your doctor before restarting, because you may need to restart on a lower dose.

Semaglutide (UK Wegovy label): take a missed dose within 5 days of the missed dose. After that, skip it and take the next one on your usual day. If more doses are missed, the label says a lower restarting dose should be considered.¹⁹

Tirzepatide (UK Mounjaro label): take a missed dose within 4 days of the missed dose. After that, skip it and take the next one on your usual day.²⁰ The label gives no rule for restarting after a long gap. Ask your doctor what dose to restart on.

Questions people ask