Weight Loss Jab Users Risk Worse Health After Stopping Treatment, Study Warns
Individuals who cease using obesity medications such as Mounjaro or Wegovy are likely to regain nearly two-thirds of the weight they lost within just one year of stopping the drugs, according to a significant new study. While this post-treatment weight gain eventually plateaus, allowing patients to typically maintain a quarter of their initial weight loss, researchers have issued a stark warning.
Potential for Adverse Health Outcomes
Scientists caution that if the regained weight consists predominantly of fat rather than lean muscle mass, individuals could find themselves "worse off than before" they commenced the injections. These weight loss jabs belong to a class of pharmaceuticals known as GLP-1 receptor agonists. They function by mimicking the GLP-1 hormone to regulate blood sugar and insulin levels, thereby suppressing appetite.
Originally developed for managing type 2 diabetes, specific formulations like semaglutide (marketed as Wegovy) and tirzepatide (Mounjaro) have received approval for use on the NHS to combat obesity. The study, conducted by researchers at the University of Cambridge, analysed data from six clinical trials involving more than 3,200 participants.
Detailed Findings on Weight Regain
The analysis, published in the journal eClinicalMedicine, indicates that after discontinuing the jabs for 52 weeks, patients regained an average of 60% of the weight they had lost. The researchers stated the findings "indicate that there is significant weight regain following cessation of GLP-1RAs".
By the 60-week mark, the regain began to taper off, stabilising at approximately 75% of the original weight lost. This suggests that a 25% reduction may be sustainable in the long term, though the composition of that maintained loss remains a critical unknown.
Brajan Budini, a medical student at the University of Cambridge's School of Clinical Medicine and Trinity College, explained the mechanism: "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."
Critical Unknown: Body Composition Changes
Budini highlighted a crucial gap in knowledge: "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."
This concern underscores the call from researchers for future trials to specifically investigate the effect of GLP-1 receptor agonists on the composition of weight loss both during active treatment and after its cessation.
Inconsistent Prescribing Guidelines
The study also criticises current prescribing protocols, noting they "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 (NICE) recommends that patients use semaglutide for weight loss for a maximum of two years, yet imposes no such time limit for tirzepatide, creating a disparity in clinical guidance.
Steven Luo, another Cambridge medical student involved in the research, emphasised the need for a holistic approach: "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."
The research concludes that while GLP-1 drugs offer a powerful tool for initial weight reduction, a strategic and supported transition off the medication is essential to prevent detrimental health outcomes related to body composition and sustained weight management.
