People who stop using the weight-loss injection Mounjaro are likely to regain weight and lose key health improvements, according to new research.
Mounjaro, which contains the drug tirzepatide, has been shown to help users lose around 20% of their body weight. However, researchers analysing data from the Surmount-4 clinical trial found that once people stop taking the medication, weight frequently returns — along with the reversal of benefits such as lower blood pressure, improved cholesterol levels and better blood sugar control.
In the study, participants used tirzepatide for 36 weeks alongside diet and exercise support. They were then split into two groups: one continued the drug for another year, while the other switched to a placebo. Of those who stopped the medication after losing at least 10% of their body weight, 82% regained at least a quarter of the weight they had lost within a year.
Researchers found that the more weight participants regained, the more their health indicators worsened. Those who regained 75% or more of their lost weight saw their cholesterol, blood pressure and blood sugar levels return to their original pre-treatment levels.
Professor Naveed Sattar of the University of Glasgow said the findings were not unexpected, as excess weight drives many of these health problems. He also warned that stopping such drugs could remove protective effects linked to reduced risk of heart failure and death.
Experts stressed the importance of long-term weight management, through sustained lifestyle changes and, where appropriate, continued medical support. Some specialists noted that weight-loss drugs can sometimes reduce motivation to maintain healthy eating and exercise habits, making long-term maintenance more difficult once medication stops.
Separate research has also suggested that women who stop weight-loss medications before or during early pregnancy may face higher risks of complications, although experts caution that more research is needed to prove a direct link.
