Adapted from BMJ 10 January 2026
The National Institutes of Health and Oxford Biomedical Research have found that after GLP-1 weight loss drugs are stopped, rapid weight regain occurs, and it occurs a lot faster than if the weight was lost by traditional dietary methods. The average time to regain the lost weight is 1.7 years.
The research covered 9,341 participants over 37 studies. Two thirds had used weight loss injections and one third had used dietary methods.
Those using the injections achieved a lot more weight loss than dietary methods, losing about 14% of their starting weight, compared to 5% for the dieters.
Currently 40.3% of US adults are obese and 26.2% are obese in the UK. Other countries with high levels include India and Egypt. This leads to higher rates of type two diabetes, cardiovascular disease, dementia and premature death.
Weight loss surgery seemed to be the most effective option, until the injections came on the scene.
The injections lead to around a 4.6 kg weight loss which is equivalent to lowering the BMI by two points. Although very effective many users stop the injections in the first year of use. The average time of use of the injections is 39 weeks. After stopping, weight gain increases at a rate of 0.4 kg a month. Within two years, the average user is back to their previous weight. Dietary strategies to lose weight have a similar trajectory.
The commonest reasons given for injection discontinuation are cost, side effects and inconvenience. Getting people to commit to healthy diets and lifestyles does work to keep weight off but most people struggle to keep going.
People in the Diabetes Prevention Programme achieved 5-7% weight loss on diet and lifestyle measures alone. Even though they did indeed regain the weight, they did experience less diabetes than the control group. However, one group that did not do as well were the people who had a BMI in the “healthy” range of 18.5 -24.9. They ended up having more diabetes than those who had not attempted weight loss in the first place. It is thought that losing muscle as well as fat was the problem. This can be prevented if people in the healthy range use exercise as the main way to lose weight.
Researchers think that the general public need to be aware that the weight loss injections are not a magic bullet and that healthy diet and lifestyle practices are still relevant and useful. They think that taxation on sugary beverages, clear food labelling and subsidies on fresh fruit and vegetables would improve diet quality generally.
Diabetes Diet 