A recent study found that people with obesity who took tirzepatide (sold as Mounjaro and Zepbound) lost more weight and trimmed more from their waists than those who took semaglutide (Ozempic and Wegovy) over 72 weeks.

Both medications belong to a class of treatments called GLP-1 receptor agonists, which mimic gut hormones to help manage blood sugar levels and appetite.

In the study, 751 adults with obesity (but without diabetes) were randomly assigned to receive either tirzepatide or semaglutide. By week 72, the group taking tirzepatide lost an average of 20.2 percent of their weight, compared to an average of 13.7 percent for those taking semaglutide.

Waist circumference also shrank more with tirzepatide, by an average of 18.4 centimeters versus 13 centimeters with semaglutide.

How These Drugs Work — and Why Results May Vary

Semaglutide is a GLP-1 receptor agonist, a drug that helps regulate insulin and slow digestion, which can reduce hunger. Tirzepatide works differently from semaglutide in that it activates two hormone receptors, GLP-1 as well as gastric inhibitory polypeptide (GIP). This may explain why it led to greater weight loss in this trial. However, this doesn’t mean tirzepatide is better for everyone.

Other factors — such as a person’s health history, how their body processes medication, or what side effects they experience — can all affect how well a treatment works. In the study, the most common side effects for both treatments were stomach-related issues like nausea or diarrhea, which tended to occur as doses increased. Most were mild or moderate in severity.

Beyond Weight Loss: Risks and Benefits of GLP-1s

Although medications like tirzepatide and semaglutide are often talked about for weight loss, they can improve health in multiple ways — including lowering the risk of heart disease and helping manage blood sugar. People living with obesity are often managing multiple health concerns, and while some people may prioritize weight loss as a key treatment goal, others may focus on improving energy, joint health, or blood sugar levels.

“The point of these medications is to improve health,” Dr. Louis Aronne, director of the Comprehensive Weight Control Center at Weill Cornell Medicine, told the Associated Press.

Notably, some research has found that people using GLP-1 receptor agonists may lose not only body fat but also some muscle. Researchers have found that between 15 percent and 40 percent of total weight lost on GLP-1s comes from lean body mass, including muscle. This could be especially important for people at risk of sarcopenia, a condition that causes muscle loss and weakness — often affecting older adults or those with certain health conditions.

The good news is that muscle loss isn’t inevitable. With the right support — including adequate protein, strength training, and guidance from a healthcare provider — it’s possible to reduce muscle loss and maintain strength while using these medications.

If you’re considering medications like these, it’s important to talk to your healthcare provider about your specific health needs and goals. They can help determine which treatment options are safest and most effective for you.

Learn more about GLP-1 drugs and other treatments for obesity.

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Have you tried GLP-1 medications like tirzepatide or semaglutide? What changes have you noticed — or what questions do you still have? Share your thoughts in the comments below, start a conversation on your Activities page, or connect with like-minded members in Groups.