As anyone who has ever dieted will attest, losing weight is only half the problem. It’s another matter entirely keeping it off for good.

Now research is suggesting that the same is true for weight-loss medications. While these GLP-1 drugs make the dieting process easier by reducing appetite and cravings, decide to stop and the rebound effect can be stronger than ever, says Dr Jack Mosley.

‘Although the weight loss is real with the weight-loss medications, so is the rebound,’ Dr Jack said on Instagram. ‘Latest research shows that 20 months after stopping the GLP-1 weight-loss medications you will typically regain all of that weight you originally lost – and your cardio-metabolic markers such as your cholesterol, your glucose and your blood pressure will return to baseline as well.’

Worryingly, research suggests that weight regain is even faster after GLP-1s than a traditional diet. ‘This 2026 study highlighted that the weight regain is much faster than the weight regain you typically see after dieting without the weight-loss medications,’ says Dr Jack. In fact, ‘it was between four and up to eight times faster.’

How to prevent ‘rebound’ weight gain

The most important step anyone using GLP-1s can take, says Dr Jack, is to change their eating habits while they are on weight-loss injections, ‘making sustainable healthy eating habits and lifestyle changes whilst you’re on these weight-loss medications to get long term results.’

It’s important to remember that weight-loss drugs are a tool, and other strategies need to be incorporated as well for successful, long-term weight loss, he adds. ‘One of the ways weight-loss drugs work is to reduce your appetite and cut down this food noise,’ Dr Jack told Good Housekeeping. ‘The way I like to think of them is as soundproof ear defenders. When you’ve taken the drugs, you have your soundproof ear defenders on, so you can go about your life and are mostly able to avoid temptations.

‘But weight-loss drugs are a tool, like anything else. When you take off those ear defenders – when you stop taking the medication – that food noise can return with a vengeance. Your appetite comes rushing back.’

He added: ‘If you strive to make improvements in your diet, focusing on eating real and filling, nutritious foods and exercising regularly, the weight-loss jabs can find a healthy place in the mix.’

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