Prescription weight-loss medications have transformed obesity care, helping many people lose significant weight and improve markers such as blood sugar, cholesterol and blood pressure. But a new study suggests those benefits may be difficult to maintain once you stop.
Researchers from the University of Oxford have analysed what happens after people stop taking weight-loss drugs and found that most tend to regain weight – often returning to their starting weight within two years. The findings were published in the British Medical Journal and are based on data from thousands of patients worldwide.
What the research found
Researchers reviewed 37 clinical studies involving 9,341 adults who had taken prescription weight-loss medications and were followed after stopping them. On average, participants had used the drugs for around 39 weeks, with follow-up lasting about 32 weeks after they had come off the drug.
The review included a range of weight-loss medicines, from older treatments to newer GLP-1 receptor agonists, which work by influencing appetite and satiety.
The team compared weight changes after stopping medication with weight changes seen after ending behavioural weight-loss programs, such as dieting and exercise.
Weight regain was common – and relatively quick
Across the studies, people regained an average of about 0.4 kilograms per month after stopping weight-loss medication. At that pace, most were projected to return to their baseline weight within around 1.5 to 2 years.
Improvements in other aspects of their health – including blood pressure, cholesterol and long-term blood glucose levels – also tended to fade. These markers generally moved back towards pre-treatment levels within about 1.4 years of stopping medication.
Importantly, the rate of weight regain was faster than that seen in people who lost weight through lifestyle alone. On average, those who had used medication regained around 0.3 kilograms more per month than those who had relied on diet and exercise, regardless of how much weight they initially lost.
Lead author Dr Sam West, a postdoctoral researcher at Oxford’s Nuffield Department of Primary Care Health Sciences, said the findings highlight a key challenge.
“These medicines are transforming obesity treatment and can achieve important weight loss,” he said. “However, our analysis shows that people tend to regain weight rapidly after stopping – faster than we see with behavioural programmes.”
Why the body rebounds
The researchers suggest the difference may lie in our habits. While medications can reduce appetite and support weight loss during treatment, they don’t necessarily require people to practise the behaviours needed to maintain weight loss long term like going to the gym or eating healthily.
“This faster regain could be because people using drugs don’t need to consciously practise changing their diet to lose weight,” said Associate Professor Dimitrios Koutoukidis, a senior author on the study. “So when they stop taking the medication they might not have developed the practical strategies that could help them keep it off.”
Professor Susan Jebb, a public health nutrition scientist and joint senior author, said the findings reinforce the idea that obesity should be approached as a long-term condition.
“Obesity is a chronic, relapsing condition, not a short-term problem with a quick fix,” she said. “When people lose weight through changes to their diet and activity, they’re practising the skills that help maintain that loss.”
The authors stress that the study does not suggest weight-loss medications lack value. Many people experience meaningful health improvements while taking them, and for some, ongoing treatment may be appropriate under medical supervision.
If you’re considering weight-loss medication or have questions about starting, continuing or stopping treatment, it’s important to speak with your GP about what’s right for you.
