- Mounjaro led to greater average weight loss than Wegovy in a 72-week trial
- Participants on Mounjaro lost more body weight and had better metabolic outcomes
- Experts say both drugs are useful but Mounjaro may suit those with more weight to lose
Mounjaro has been found to be more effective than Wegovy in the first direct comparison trial of two major weight-loss drugs.
Both medications led to substantial weight loss, but those who took Mounjaro lost around 20% of their body weight on average, compared with 14% for those on Wegovy.
The trial lasted 72 weeks and involved 750 people with obesity, each weighing about 113kg on average.
The two drugs work by altering how the brain regulates appetite. Wegovy, also known as semaglutide, mimics a gut hormone that switches off hunger signals.
Mounjaro, or tirzepatide, goes a step further by mimicking two hormones, which may explain its stronger results.
According to findings presented at the European Congress on Obesity in Malaga and published in the New England Journal of Medicine:
- 32% of people on Mounjaro lost at least a quarter of their body weight, compared to 16% on Wegovy
- Waistlines shrank by 18cm on average for those taking Mounjaro, versus 13cm for Wegovy users
- Mounjaro users saw more improvement in blood pressure, cholesterol and blood sugar levels
- Both drugs had similar side-effects
- Women tended to lose more weight than men
The trial was led by Dr Louis Aronne at the Comprehensive Weight Control Center at Weill Cornell Medicine in New York.
He said most people would benefit from semaglutide, but those with more weight to lose might do better with tirzepatide.
In the UK, both medications are available through specialist weight management services and private purchase.
Professor Naveed Sattar from the University of Glasgow described them as good treatment options and noted that while some patients are happy with 15% weight loss, others will seek even more.
However, it is worth noting that Wegovy is already approved for other uses, including reducing the risk of heart attacks.
Mounjaro has not yet completed equivalent trials.
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There is still significant research under way into weight-loss drugs, including testing higher doses, new formulations like tablets, and entirely new compounds.
Professor Sattar suggested we may soon reach a point where preventing obesity through medication is possible, though he stressed that creating a healthier society would always be a better solution.
