Research indicates that individuals using weight loss medications tend to regain all lost weight within a year after stopping. A recent analysis involving 11 studies on both older and newer GLP-1 weight loss drugs, conducted by the University of Oxford, revealed that participants lost an average of 8kg while on these injections but typically returned to their original weight within about 10 months of discontinuation.
This study, shared at the European Congress on Obesity, highlighted that even those on more modern, higher-dose medications like Wegovy and Mounjaro experienced weight regain after ceasing treatment. While users of semaglutide (Wegovy) and tirzepatide (Mounjaro) lost an average of 16kg—twice the amount compared to older medications—they also regained approximately 9.6kg within a year, suggesting they could easily regain all 16kg in just over 20 months.
Researchers examined data from 6,370 adults involved in eight randomized controlled trials and three observational studies, where 1,465 participants were on higher-dose injections specifically for weight loss.
A prior analysis from the same team had looked into the effectiveness of various diets, revealing that while individuals also regained weight after stopping diets, the process was notably slower and took at least five years to revert to initial weight levels.
Co-author Susan Jebb, who is a professor of diet and population health at the University of Oxford, noted, “These drugs are very effective at helping you lose weight, but when you stop them, weight regain is much faster than after stopping diets.”
The study’s findings pose concerns for the NHS, especially given that current guidelines suggest patients shouldn’t remain on weight loss injections for more than two years. Moreover, many individuals might choose to stop the treatment due to cost (particularly if purchasing privately), side effects, or a lack of continued weight loss.
Jebb questioned the value of NHS investing in these drugs if patients only use them briefly and subsequently regain weight, suggesting a need for a re-evaluation of whether these therapies should be seen as long-term solutions. “Either people really have to accept this as a treatment for life, or we need to think hard about how to support individuals once they stop the medication,” she remarked.
While the study did not establish causality, Jebb speculated that the rapid weight regain might relate to the way individuals lose weight with medications versus diets—dieting requires self-control and effort, while drugs suppress hunger. Once the drugs are withdrawn, those strategies may not be in place, making weight maintenance challenging.
Commenting on the study, Tam Fry from the National Obesity Forum said that it’s not surprising for individuals who use GLP-1 drugs to regain weight without sincere lifestyle changes. “GLP-1 is not the quick fix many users think it is,” he added.
Jane Ogden, a health psychology professor at Surrey University, stated that simply sending people back to their normal lives after coming off the injections is ineffective. “They will require psychological counseling, behavior change, and nutritional support to sustain healthier habits and keep the weight off,” she explained.
Ogden suggested that the NHS should implement a supportive, stepped care approach—offering low-cost online or group support, or more intensive personal sessions.
Jason Halford from the European Association for the Study of Obesity emphasized the necessity of equipping patients with the tools to make behavioral adjustments needed to maintain the benefits of treatment, asserting that weight loss jabs should complement, rather than replace, behavioral change.
