Weight regain faster after stopping weight-loss drugs than diet programmes, study finds
People who stop taking weight-loss medicines tend to regain weight more quickly than those who complete diet and behavioural programmes, according to a major new analysis published today in The BMJ.
Researchers from the University of Oxford’s Nuffield Department of Primary Care Health Sciences found that weight regain after discontinuing weight management drugs occurred at a significantly faster rate than after ending lifestyle-based interventions such as diet and exercise support. The findings raise important questions about the long-term use of these medicines, particularly as real-world data suggests around half of people prescribed GLP-one receptor agonists stop treatment within twelve months.
The systematic review and meta-analysis examined 37 studies involving 9,341 adults who had used weight-loss drugs for an average of 39 weeks before stopping. Participants were followed for around 32 weeks after treatment ended.
Across all medicines studied, weight increased by an average of 0.4 kilograms per month after discontinuation. At this pace, researchers estimate that people would return to their original weight within around one and a half to two years.
For newer drugs such as semaglutide and tirzepatide, weight regain was even faster, averaging 0.8 kilograms per month. Based on this rate, participants were projected to return to baseline weight within approximately 18 months. However, the researchers caution that longer-term data beyond 12 months remains limited for these newer treatments.
Crucially, when compared with behavioural weight-loss programmes, weight regain after stopping medication was faster by around 0.3 kilograms per month, regardless of how much weight had been lost initially. Although combining behavioural support with medication resulted in greater weight loss during treatment, it did not appear to slow the speed of regain once drugs were stopped.
The study also found that improvements in cardiometabolic health markers, including blood glucose, blood pressure, cholesterol and triglycerides, reversed after treatment cessation. These measures were estimated to return to baseline levels within around one point four years.
Dr Sam West, lead author of the study, said the findings highlight the chronic nature of obesity. “These medicines are transforming obesity treatment and can achieve important weight loss. However, people tend to regain weight rapidly after stopping, faster than we see with behavioural programmes,” he said. “This is not a failure of the medicines, but a reminder that obesity is a long-term, relapsing condition.”
Senior author Associate Professor Dimitrios Koutoukidis suggested that the faster regain may reflect a lack of skill development. “When people lose weight through diet and activity changes, they are practising behaviours that help maintain that loss. With medication, weight loss may occur without developing those strategies,” he said.
The findings come shortly after NICE published new quality standards recommending at least one year of structured support following treatment. They also raise concerns given that an estimated nine in ten people currently using weight-loss drugs in the UK are accessing them privately, often without ongoing clinical or behavioural support.
Professor Susan Jebb, a joint senior author, said the results underline the need for a more holistic approach. “There is no quick fix for obesity. These findings reinforce the importance of long-term support, realistic expectations and strong prevention strategies to reduce weight gain across the population.”
The researchers acknowledge limitations, including short follow-up periods and limited data on newer drugs. Nevertheless, they argue the evidence is clear - effective obesity treatment requires sustained commitment from both individuals and health systems, not short-term interventions alone.