Mounjaro Better for Weight Loss Than Ozempic, Study Finds

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A new real-world study found that people taking Mounjaro lost more weight faster compared to people who took Ozempic. Sandy Huffaker for The Washington Post via Getty Images
  • In a real-world study, Mounjaro showed greater weight loss compared to Ozempic.
  • Patients taking Mounjaro were more likely to hit weight-loss benchmarks and drop more pounds overall.
  • The study is the first to compare the two drugs head-to-head in a real-world setting using healthcare data.

Eli Lilly’s Mounjarotrumps Novo Nordisk’s Ozempic in the first real-world comparison of weight loss in patients with obesity.

According to a new study in JAMA Internal Medicine, Mounjaro (tripeptide) showed better results across multiple weight-loss benchmarks and overall weight loss compared to Ozempic (semaglutide).

Both are part of a class of drugs known as glucagon-like peptide receptor agonists (GLP-1), which are indicated for the treatment of type 2 diabetes and obesity.

GLP-1 drugs work by mimicking natural hormones in the gut and brain that control blood sugar and appetite. They also cause weight loss by slowing digestion and imparting feelings of fullness and satiety.

Ozempic and Mounjaro are both FDA-approved for the treatment of type 2 diabetes, but are frequently used “off-label” for obesity.

The drugs are sold under different trade names, Zepbound (tirzepatide) and Wegovy (semaglutide), when indicated for the treatment of obesity.

Prior trials have shown patients taking Ozempic lost as much as 16% of their total body weight. Mounjaro showed even more impressive results, with some patients losing more than 20%.

However, due to differences in how the trials were conducted, they cannot be directly compared.

New real-world data now suggests that Mounjaro is, in fact, the more effective of the two for weight loss.

“This data is informative and reinforcing because it supports our experiences in real-world clinical practice — people lose more weight with tirzepatide than with semaglutide,” Beverly Tchang, MD, an endocrinologist, Spokesperson for the Obesity Society, and Assistant Professor of clinical medicine at Weill Cornell Medicine, told Healthline. Tchang wasn’t affiliated with the research.

The study found that across a one-year time period, patients taking tirzepatide were more than twice as likely to achieve a weight loss of 10% or greater and three times as likely to achieve a weight loss of 15% or greater compared to semaglutide.

Total weight loss at various intervals, including three, six, and 12 months, was also greater among those taking tirzepatide. The gap between the two drugs also increased with time. At three months, the average weight loss for tirzepatide was 5.9% compared to semaglutide’s 3.6%. By one year, patients taking tirzepatide lost more than 15% of their body weight, while those taking semaglutide lost about 8%.

“As a practicing cardiologist and researcher, having the most timely data to inform patient care is paramount,” Ty Gluckman, MD, Medical Director at the Center for Cardiovascular Analytics, Research, and Data Science (CARDS) at Providence Heart Institute, and an author on the paper, told Healthline.

“Because tirzepatide was only approved by the FDA in mid-2022 for type 2 diabetes, the ability to rigorously analyze its use (on- and off-label) for a broad population of patients with overweight or obesity, not just a subset captured in insurance databases, has the power to greatly improve our understanding of how these agents are being used in everyday practice and the effect that they’re having,” said Gluckman.

To conduct their study, researchers at Truveta, a healthcare data and analytics company that currently includes 30 health systems across the US, tapped into electronic health records and prescriber data.

They identified adults with overweight or obesity who began taking either Ozempic or Mounjaro for the first time between May 2022 and September 2023. They could not have previously been prescribed a GLP-1 drug to be included in the study.

In total, more than 40,000 patients met criteria for the study who had taken one of the two drugs. After matching patients taking tirzepatide to characteristically similar individuals taking semaglutide, the total cohort remaining was 18,386. The average age of patients in the study was 52. The cohort was predominantly female (70%) and white (77%). About 12% of the cohort was Black and 2% were Asian.

More than half of the patients included in the study were living with type 2 diabetes.

Researchers also observed whether either drug resulted in more adverse health events.

GLP-1 drugs are known to be associated with common gastrointestinal effects, including nausea, diarrhea, and vomiting. However, more serious complications have also occurred, including bowel obstruction or ileus, which is potentially fatal.

Both Ozempic and Mounjaro resulted in a similar amount of adverse events, according to the study.

Moderate-to-severe outcomes that were observed included bowel obstruction, gastroparesis, pancreatitis, and cholelithiasis (gallstones).

“Gastrointestinal side effects of these medications have been widely reported as well, but we didn’t find a difference in the rates of moderate to severe gastrointestinal adverse events between the two medications,” Tricia Rodriguez, PhD, a scientist at Truveta Research, and lead author on the paper, told Healthline.

The study also yielded some other significant findings. Consistent with other clinical trials, weight loss was greater among patients without type 2 diabetes. The reasons for these effects are still unclear.

Additionally, more than 50% of patients in both the tripeptide group and semaglutide group stopped taking their medication within one year.

Researchers theorize that this could be linked to a number of different factors, including the cost and accessibility of the medications or side effects. The study doesn’t conclude why the discontinuation rate is so high but notes that more research needs to be done in this area.

In a first real-world comparison using healthcare data, Mounjaro (tirzepatide) outperformed Ozempic (semaglutide) across numerous weight-loss benchmarks.

Patients taking Mounjaro were two times as likely to achieve a weight loss of 10% or greater and three times as likely to achieve a weight loss of 15% or greater.

The safety profile of both drugs was similar in terms of adverse gastrointestinal events during the study period.



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