People who stop using the weight-loss injection Mounjaro tend to regain weight and lose other health improvements, according to new research.
Mounjaro, which contains tirzepatide, has been shown to help people lose around 20% of their body weight over 72 weeks. Previous studies found that much of this weight is regained after the drug is stopped. New findings from the Surmount-4 clinical trial show that additional benefits — including lower blood pressure, improved blood sugar levels and reduced “bad” cholesterol — are also reversed when treatment ends.
In the study, all participants used tirzepatide for 36 weeks before being split into two groups: one continued the drug for another year, while the other switched to a placebo. Among 308 participants who had lost at least 10% of their body weight, 82% of those who stopped the drug regained at least a quarter of the weight they had lost within a year.
Researchers found that the more weight people regained, the more their heart and metabolic health markers returned to baseline levels. Those who regained the most weight saw their blood pressure, cholesterol and blood sugar levels return to where they were before treatment began.
Experts said the findings highlight the difficulty of maintaining long-term weight loss and the importance of ongoing support — either through lifestyle changes or continued medication — to preserve health benefits.
Additional research has suggested stopping weight-loss drugs before or during pregnancy may be linked to higher risks of complications, though experts stress that more studies are needed to confirm cause and effect.
