Weight Loss Injections Linked to Rapid Weight Regain Post-Treatment: Study Finds

New Delhi: A new analysis by the University of Oxford has found that people taking GLP-1 weight loss drugs typically regain all the weight they lost within a year of stopping the medication. The findings, presented at the European Congress on Obesity, analyzed 11 studies involving both older and newer GLP-1 drugs and revealed a consistent pattern of rapid weight regain after treatment ends.

The study examined data from 6,370 adults across eight randomized controlled trials and three observational studies. On average, patients lost 8kg while on weight loss injections, but regained the lost weight within 10 months after stopping. Even among those using newer, high-dose treatments like semaglutide (Wegovy) and tirzepatide (Mounjaro)—who lost an average of 16 16kg—the weight regain was significant, with patients gaining back 9.6kg within a year. At that pace, the full amount lost could be regained in just over 20 months.

“These drugs are very effective at helping you lose weight, but when you stop them, weight regain is much faster than [after stopping] diets,” said Susan Jebb, the co-author of the study and professor of diet and population health at the University of Oxford.

The findings raise issues for the NHS, as NICE guidelines state people should not be on weight loss injections for more than two years. Additionally, many patients give up the treatment, whether because they are buying it privately so cannot afford it, because the side effects do not suit them or because they are not losing weight anymore.

While the study did not show causality, Jebb speculated that the difference in how fast people put weight back on could be since diets are hard and people have to practice restraint to lose weight, whereas if you are taking a drug that knocks your hunger out completely, you don’t have to make that effort. “So when the drugs are then taken away, you haven’t got those sort of behavioural strategies in place that help keep the weight off.”