People taking Mounjaro (tirzepatide) lost substantially more weight on average than those taking competitor Ozempic (semaglutide), according to a major new real-world study of over 18,000 overweight and obese adults.
After one year, people on Mounjaro had lost 15% of body weight on average, compared to only 8% for Ozempic users.
Both injectable type 2 diabetes medications work by mimicking the hormone GLP-1. But Mounjaro also activates a second gut hormone, GIP, which may give it greater weight loss powers. With obesity affecting over 70% of American adults, Mounjaro’s increased effectiveness could have big implications.
The Study: Large-Scale, Real-World Data on 18,000+ Patients
The study was conducted by data analytics firm Truveta, using medical records from 30 major U.S. healthcare systems. It included over 18,000 overweight or obese adults prescribed Ozempic or Mounjaro for either diabetes or weight loss from May 2022 to September 2023.
Roughly half had type 2 diabetes. The other half took the drugs “off-label” for weight loss alone, at their doctors’ recommendation. By comparing results in both groups, researchers aimed for real-world insights on how the drugs perform.
Patients using Mounjaro saw greater average percentage weight loss at every time point. At 3 months, Mounjaro users had lost 6% of body weight versus 4% for Ozempic. At 6 months, it was 10% versus 6%.
After a year, the 15% weight loss on Mounjaro was nearly double Ozempic’s 8%. Side effects were very similar for both drugs. The most common were nausea, vomiting, and gallstones.
Understanding Mounjaro’s Stronger Weight Loss Effects
Both Mounjaro and Ozempic activate GLP-1, a hormone that stimulates insulin production while suppressing appetite. But Mounjaro also binds to the GIP receptor, powering up its effects.
Activating GIP as well as GLP-1 could be the key reason why Mounjaro appears more potent for weight loss in both clinical trials and real-world data. However, head-to-head studies are still limited.
Notably, the Truveta study used doses of Ozempic and Mounjaro approved for diabetes, not the higher doses now FDA-approved specifically for treating obesity (Wegovy and Zepbound). So more research is needed.
Why Many Patients Stopped Treatment
Roughly half the patients studied stopped filling their prescriptions over the 12-month period. Shortages of both drugs likely played a role, making consistent access a challenge.
The similar side effects profiles also point to tolerability issues leading some patients to discontinue. While effective, both medications have known gastrointestinal side effects that can be difficult to manage for some.
What Doctors and Companies Say About the Results
UCLA specialist Dr. Mopelola Adeyemo says real-life results often differ from clinical trials. She stresses finding the specific medication that patients can stick with long-term. Access and side effects may dictate effectiveness more than potency claims.
Novo Nordisk, makers of Ozempic/Wegovy, note that different doses weren’t compared. Eli Lilly, which makes Mounjaro, doesn’t recommend off-label use but says head-to-head obesity trials are upcoming.
- Activating an additional gut hormone likely boosts Mounjaro’s weight loss effects over Ozempic.
- But with high discontinuation rates, individual tolerability is key in real-world practice.
- Companies emphasize comparing approved obesity doses and awaiting further trial data.
- Doctors focus on finding the specific drug that works best for each patient long-term.
The Bottom Line for Patients
With the majority of American adults now overweight or obese, having effective medical options for weight loss is crucial. For those considering drugs like Mounjaro or Ozempic, what should patients know?
For patients with obesity struggling to lose weight through diet and lifestyle alone, these GLP-1 drugscan be life-changing. New real-world data gives doctors and patients key insights into their real-life effectiveness.
On average, Mounjaro appears to enable greater weight loss than Ozempic. But there is no universally “best” option. The medication that each patient can stick with long-term is the right choice.
Stay in close contact with your doctor about expectations, results, side effects, and access challenges. As more comparative effectiveness data emerges and shortages hopefully resolve, patients have more reason for optimism around medical options for managing obesity over the long haul.