The new class of weight-loss drugs promises staggering results and, in most cases, delivers them. But if, after months of weekly injections, you hit your target weight and decide to stop taking the medication, there’s something you should know: you’re likely to put the weight back on.
Studies on these drugs have shown that people with obesity can lose 15–20 per cent of their body weight in just over a year. But if they halt the treatment, the research shows they’re likely to regain two-thirds of the weight they lost over the following 12 months.
These drugs – known collectively as GLP-1 agonists, but prescribed under various brand names (including Ozempic, Wegovy, Mounjaro) – mimic the effect of naturally produced hormones that make you feel full. By reducing your appetite, the drugs help you eat less and lose weight – but their effects only last as long as you take them.
That’s true whether you’re taking them to get a smaller waistline, or as a protective measure against weight-related diseases, such as type 2 diabetes, heart disease and certain cancers.
The solution to this problem might seem simple: keep taking the drug. But not everyone can face a lifetime of weekly injections, let alone the high costs of the medication and its possible side effects.
“Taking a treatment forever is probably not what people are looking for, particularly if they’re paying for it themselves,” says Prof Susan Jebb, a nutrition scientist at the University of Oxford. “People want to lose weight and keep it off.”
Roughly half of the people who start taking a weight-loss drug decide to stop within a year. If that’s you, while regaining the weight you lost is likely, there are strategies you can adopt to help keep it off.
Weight regain is a persistent problem
After any form of weight loss – natural or pharmaceutically assisted – there’s a risk of regain. It’s a problem that nutrition scientists have grappled with for years.
“Maintaining weight loss is the big challenge in weight management,” says Jebb. “We’ve got lots of ways to help people lose weight, but we’re not very good at helping them keep the weight off.”
That’s because, after significant weight loss, the body is primed to return to its previous weight. Your hunger ramps up but your metabolism slows down, so eating even small amounts of food can lead to weight gain.
Weight-loss drugs make the challenge even harder. While they mimic fullness hormones like GLP-1, they might also reduce your body’s own natural satiety. That means when you come off the drug, your hunger may be even greater than after a traditional diet.
So, the weight often comes back – and fast. Jebb’s team at Oxford found that, on average, people return to their original weight within two years of stopping treatment. But not everyone reacts the same.
“There’s huge variability,” explains Jebb. “It’s really difficult to work out why some people keep it off and some people don’t. The short answer is, we don’t yet know.”
Until they do, Jebb says nutrition scientists have to rely on the old, familiar advice: diet and exercise. That might not be what you want to hear, especially if you decided to try weight-loss drugs after years of struggling with traditional lifestyle-based advice. But right now, it’s the best we’ve got.
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Prepare before you quit
The most powerful strategy, according to Prof Giles Yeo – an obesity scientist at the University of Cambridge – is to set yourself up for success before you come off the weight-loss drugs.
“You have to take the opportunity while you’re on the drug to learn new habits,” he says. “Being on these drugs takes away the most difficult obstacle to learning new dietary behaviours: hunger.”
With your appetite suppressed, it may be easier to eat smaller, healthier meals and change your behaviour. For instance, if you eat when you’re stressed or in front of the TV, Yeo says these drugs make it easier to nip those patterns in the bud.
Developing new habits that you can maintain after you stop taking the drug is “the only way to give yourself a fighting chance of keeping the weight off,” he says.
Yeo also recommends using your time on weight-loss medication to build exercise into your routine.
Studies show that physical activity can help weight loss stick. That was the conclusion of a Danish study from 2024, which found people were more likely to maintain at least 10 per cent of their weight loss if they participated in an exercise programme after quitting their weight-loss drug.
“That tells us exercise is helpful,” says Jebb. “But only among the kind of people who are willing to do an intensive, supervised exercise programme.”
Strategies to manage your appetite
It’s one thing to build healthy habits while you have no appetite; it’s quite another to avoid snacks when your body is crying out for calories. But savvy dietary choices can take the edge off these cravings.
The key is to prioritise satiating nutrients like protein and fibre over carbohydrates.
“Protein and fibre both make you feel fuller by travelling further down the gut and naturally releasing GLP-1,” says Yeo. “You’re trying to maintain higher levels of GLP-1 as you eat. It’ll never be as high as it would with a drug, but that’s the aim.”
There’s even research about particular foods being satiating, such as eggs. Studies have repeatedly shown that eating eggs for breakfast helps us feel fuller for longer and eat less for lunch, compared to higher-carb options such as cereal or toast.
Other high-protein foods may have a similar effect, such as lean meats, fish, tofu or Greek yoghurt.
Then there are foods that contain specific fats or fibres that may slightly boost GLP-1, including berries, olive oil, nuts, avocados, oats, lentils, beans, leeks, onions and asparagus.
Finally, simply eating more slowly can make you feel fuller, even when you’re eating the same thing as someone who’s wolfing it down.
“Eating more slowly, having more fibre, a bit more protein and less sugar – all these are good,” Jebb says. “But there’s no silver bullet – and these are all little things that we’ve heard before.”
Help is on the way
New habits, healthier food and exercise still won’t be enough for everyone to prevent weight regain.
“You’re going to have to take conscious action to eat less, which most people have found really hard to do unaided in the past,” says Jebb. “If you’ve been on these drugs, you’ve likely got a genetic predisposition to be overweight.”
According to Yeo, these tips will only help a subset of the population, whose excess weight was caused more by diet and behaviour than genetics.
“There’s a spectrum of obesity,” he says. “How severe your obesity is, and why you ended up with it, will powerfully inform whether or not you’ll react to this.”
For those who need medical intervention to maintain their weight loss, help is on the way. Pharmaceutical companies are trialling lower-dose weight-loss drugs, in pill and injectable form, to help people keep the weight from returning while they gradually taper off the medication.
Nevertheless, research shows that even temporary weight loss can benefit your health in the long run.
“Any time spent back down at a healthy weight will have longer-term positive effects,” says Yeo. “And the longer you spend at a healthy weight, the better your long-term outcomes. So, I do think [the drugs] are worthwhile, even if the weight comes back.”
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