What did the research discover?
Researchers examined how two GLP-1 agonist weight-loss medications, tirzepatide (sold as Mounjaro) and semaglutide (sold as Ozempic), perform when used by patients when prescribed in routine medical care. Both medicines are used to treat overweight and obesity, but until recently there was limited information comparing how well they work outside of clinical trials.
To study this, scientists used a large U.S. electronic health record database that collects medical information from hospitals and clinics across the country. They looked at adults with obesity or overweight who had at least one obesity-related health condition and who started one of the two medications between December 2023 and June 2024. People with diabetes were not included in the study.
In total, 2,396 adults were studied. Among them, 1,003 people were treated with tirzepatide and 1,393 people were treated with semaglutide. Researchers followed these patients for six months after they began treatment and measured changes in body weight, body mass index (BMI), blood pressure, and other cardiometabolic health markers.
Both medications helped patients lose weight, but tirzepatide led to greater weight loss overall. After six months, patients taking tirzepatide lost about 11.15% of their body weight on average, compared with about 8.83% for those taking semaglutide.
Tirzepatide users were also more likely to reach common weight-loss goals. For example:
- About 86% of patients on tirzepatide lost at least 5% of their body weight, compared with about 75% of patients on semaglutide.
- 59% of tirzepatide users lost at least 10% of their weight, compared with 38% of semaglutide users.
In addition to weight loss, the researchers also looked at several health measurements. People taking tirzepatide showed slightly larger improvements in BMI, blood pressure, and hemoglobin A1c (a measure related to blood sugar levels). These results suggest that tirzepatide may also provide modest benefits for some heart-related risk factors.
Overall, the findings showed that tirzepatide produced greater weight reduction and helped more people reach meaningful weight-loss targets during the six-month follow-up period.
How can I apply this information?
This study provides new research showing how weight-loss medications may work in everyday medical practice. The results suggest that tirzepatide may lead to somewhat greater weight loss than semaglutide over the first six months of treatment.
However, it is important to remember that this study is research, and medication decisions should always be made with a healthcare professional. Doctors consider many factors when choosing a treatment, including a person’s medical history, other health conditions, medication side effects, and cost or insurance coverage.
The study also only followed patients for six months, so it does not show what happens with longer treatment. Weight loss from these medications may continue over time, and long-term studies are still important for understanding lasting results.
For many people with obesity, medications like tirzepatide or semaglutide can be helpful tools. But they usually work best when combined with healthy lifestyle habits such as balanced nutrition, regular physical activity, and ongoing medical support.
When you talk to your health care professional, they can help you determine which medication is appropriate for you and how it might fit into a complete weight-management plan.
Source:
le Roux CW, Done N, Brnabic AJM, Zion A, Lipkovich I, Kadziola Z, et al. Comparative effectiveness of tirzepatide and semaglutide for obesity management in US clinical practice: a 6-month retrospective cohort study. Journal of Endocrinological Investigation. 2026;49:413-423. Available from: https://doi.org/10.1007/s40618-025-02792-1.
