People who stop using the weight-loss injection Mounjaro not only tend to regain lost weight, but also see a reversal in key health improvements such as lower blood pressure and reduced “bad” cholesterol, according to new research.
Mounjaro, which contains the drug tirzepatide, has been shown to help people lose around 20% of their body weight over 72 weeks. However, previous studies have already shown that much of this weight is often regained once treatment stops. The latest findings suggest that the wider heart-health benefits also fade as weight returns.
The research, published in JAMA Internal Medicine, analysed data from the Surmount-4 clinical trial. Participants took tirzepatide for 36 weeks alongside diet and exercise advice, then were split into two groups: one continued the drug for another year while the other switched to a placebo without knowing which group they were in.
Among 308 participants who had initially lost at least 10% of their body weight, 82% regained at least a quarter of that weight within a year of stopping the medication. Greater weight regain was linked to worsening waist size, cholesterol, blood pressure and blood sugar levels, with those regaining most weight returning to their original baseline health levels.
Professor Naveed Sattar of the University of Glasgow said the findings were not surprising because excess weight strongly drives high blood pressure and poor metabolic health. He also warned that stopping the injections could remove potential protection against heart failure and premature death suggested in earlier studies.
Experts stressed the importance of long-term weight management, combining lifestyle changes with ongoing medical support. Professor Jane Ogden of the University of Surrey noted that some people rely on the drug without developing lasting habits around diet and exercise, making weight regain more likely after stopping.
Separate research has also suggested that women who stop these drugs shortly before or during pregnancy may face higher risks of complications, although experts cautioned that more research is needed to confirm a direct cause.
