People who stop using the weight-loss injection Mounjaro (tirzepatide) not only tend to regain weight but also lose key health improvements, including better blood pressure, cholesterol and blood sugar control, according to new research.
The findings come from the Surmount-4 clinical trial, in which participants with obesity or weight-related health problems first took tirzepatide for 36 weeks alongside diet and exercise support. Those who had lost at least 10% of their body weight were then split into two groups: one continued the drug for another year, while the other switched to a placebo without knowing which they were receiving.
Among those who stopped the drug, 82% regained at least 25% of the weight they had lost within a year. Researchers found that greater weight regain was closely linked to the return of higher blood pressure, increased “bad” cholesterol, larger waist size and worse blood sugar control. In participants who regained 75% or more of their lost weight, these health measures largely returned to their original baseline levels.
Experts say the results are not surprising. Professor Naveed Sattar of the University of Glasgow noted that weight regain typically brings back cardiometabolic risk factors and that stopping the drug may also remove its protective effects against serious heart problems. He added that long-term weight maintenance remains a major challenge, though more sustainable strategies may emerge in the future.
Other experts pointed out that weight-loss injections do not always lead to lasting healthy eating or exercise habits, meaning many people return to old behaviours once they stop taking the medication.
Separate research also suggests that women who stop these medications shortly before or during early pregnancy may face higher risks of weight gain, preterm birth and pregnancy-related complications, though experts caution that more research is needed to confirm direct cause and effect.
Overall, researchers conclude that long-term medical and lifestyle support is likely necessary to sustain both weight loss and its associated health benefits.
