A Cambridge University study found people who stop taking weight loss jabs such as Mounjaro and Wegovy regain almost two-thirds of the weight they lost
06:36, 05 Mar 2026Updated 07:39, 05 Mar 2026
Mounjaro and Wegovy are approved by the NHS for weight loss(Image: Kateryna Borodina via Getty Images)
People taking obesity jabs such as Mounjaro or Wegovy will put back on almost two thirds of the weight they shed within a year of stopping the drugs, new research suggests. However, the phase of gaining weight post-treatment is likely to level off, with patients managing to maintain a quarter of the weight lost.
Despite this, scientists have cautioned that if regained weight is predominantly fat, people could “be worse off than before” they began the jabs. Weight loss jabs are a class of medications known as GLP-1 receptor agonists, which function by mimicking the hormone GLP-1 to regulate blood sugar and insulin levels.
They were originally developed as a treatment for type 2 diabetes, but certain types such as semaglutide (Wegovy) and Mounjaro (tirzepatide) are approved for use on the NHS to help tackle obesity. The study by scientists at the University of Cambridge included six trials involving more than 3,200 people.
The analysis suggests that after stopping the jabs for 52 weeks, on average people regained 60% of the weight they lost. Scientists said the findings, published in eClinicalMedicine, “indicate that there is significant weight regain following cessation of GLP-1RAs”.
However, by 60 weeks, scientists said the regain started to taper off at 75% of the original weight lost, suggesting 25% may be sustained in the long-term.
Users are being warned(Image: Svitlana Pietukhova via Getty Images)
Brajan Budini, a medical student at the School of Clinical Medicine and Trinity College, University of Cambridge, said: “Drugs such as Ozempic and Wegovy act like brakes on our appetite, making us feel full sooner, which means we eat less and therefore lose weight.
“When people stop taking them, they are essentially taking their foot off the brake and this can lead to rapid weight regain.
“Our projections show that even though people regain most of the weight they have lost, they still maintain some of the weight loss, but what we currently don’t know is if the same proportion of lean mass is recovered.
“If the regained weight is disproportionately fat, individuals may ultimately be worse off than before in their fat-to-lean mass ratio, which may have adverse consequences for their health.”
Wegovy is administered via a pen injector(Image: Alamy/PA)
Call for further studies
Scientists have urged future studies to examine the impact of GLP-1RAs on body composition during and following treatment. They noted that existing prescribing guidance for GLP-1RAs “are inconsistent and largely inadequate in addressing the risk of weight regain following treatment cessation”.
For instance, the National Institute for Health and Care Excellence advises that patients should take semaglutide for weight management for a maximum of two years, though no such restriction exists for tirzepatide.
Steven Luo, a fellow medical student at the School of Clinical Medicine and Trinity College, said: “When stopping weight loss drugs, doctors and patients should be aware of the potential for weight regain and consider ways to mitigate this risk.
“It’s important that people are given advice on improving their diet and exercise, rather than relying solely on the drugs, as this may help them maintain good habits when they stop taking them.”