Stopping weight-loss injections like Wegovy and Mounjaro UK may trigger rapid rebound weight gain, new research finds.
People in the UK using weight-loss injections such as Wegovy and Mounjaro could experience rapid rebound weight gain after stopping treatment, faster than those who lose weight through traditional diet and exercise – according to a new study published in the British Medical Journal (West, 2026). The Times
The research suggests that adults who take GLP-1 weight-loss drugs commonly shed around 20% of their body weight during treatment.
But once they stop these injections, many regain weight quickly — at roughly 0.8kg per month on average — with most returning to their original weight in about 18 months. This pace of weight regain is significantly faster than typical post-diet weight rebound. The Guardian
Experts say this pattern of weight regain after Wegovy or Mounjaro highlights the need for clear NHS-aligned guidance and long-term support for people using these medicines.
Dr Susan Jebb, one of the study’s lead researchers, warned that individuals should be aware of the risk of fast weight regain once weight-loss injections stop.
She noted that while these medications can deliver substantial short-term weight loss, the benefits may reverse without ongoing management. The Times
The analysis covered data from 37 clinical studies involving more than 9,000 participants, comparing outcomes for those on injectable weight-loss drugs with conventional dieting, exercise or other non-injectable approaches. The Times
Only a subset of these studies focused on newer GLP-1 injections licensed in the UK, like Wegovy and Mounjaro, and follow-up after stopping treatment was generally limited to about a year — meaning the true long-term patterns of weight rebound are estimated rather than fully documented. The Guardian
By contrast, people who lose weight through traditional diet and exercise in UK settings tend to regain weight more slowly, often maintaining weight loss for several years before returning to previous levels — albeit with individual variations. The Times
NHS England and UK health bodies recommend that GLP-1 medications be combined with structured lifestyle and behavioural support to sustain weight management outcomes. NHS England
