People who discontinue the weight-loss drug Mounjaro tend not only to regain lost weight but also lose other health improvements linked to the medication, new research shows.
Mounjaro, which contains tirzepatide, has surged in popularity, with previous studies showing average weight loss of around 20% after 72 weeks of treatment.
However, earlier findings have already indicated that much of this weight returns once treatment stops.
Researchers analysing data from the Surmount-4 clinical trial now report that gains such as reduced blood pressure, lower LDL (“bad”) cholesterol, and improved blood glucose levels also diminish once patients stop taking the medication.
Naveed Sattar, professor of cardiometabolic medicine at the University of Glasgow, said the results were expected, noting that regained weight typically drives blood pressure and glucose levels back up.
He added that long-term weight maintenance remains challenging but suggested that more affordable long-term strategies may emerge.
The study, published in Jama Internal Medicine, examined participants with obesity or who were overweight with additional health concerns. After 36 weeks of tirzepatide alongside lifestyle support, participants were split into two groups: one continued the drug for another year, while the other received a placebo.
Among the 308 participants who had lost at least 10% of their body weight before switching to placebo, 82% regained at least a quarter of their lost weight within a year.
Greater weight regain correlated with the reversal of improvements in cholesterol, waist size, blood pressure, and glucose. Those who regained 75% or more of their lost weight saw their cardiometabolic markers return to baseline.
Researchers said the findings highlight the need for sustained lifestyle changes and long-term obesity treatments to preserve health benefits.
Experts also warn that weight-loss drugs do not always build healthier eating habits, meaning people often revert to old behaviours once treatment ends.
Another study suggests women who stop such medications before or early in pregnancy may face additional risks, though researchers caution that more evidence is needed.
