Semaglutide vs Tirzepatide: Which Is Better for Weight Loss?
In the first head-to-head trial, tirzepatide produced more weight loss than semaglutide, about 20 percent of body weight versus about 14 percent over 72 weeks. Tirzepatide works on two hormone pathways instead of one, which is the leading explanation for the edge. That said, both are highly effective, and the better choice for you also comes down to side effects, cost, coverage, and how your own body responds.
Patients ask me this constantly, and it is a smart question. In my more than 20 years in medicine, I have learned that the best drug on paper is not always the best drug for the person in front of me. Here is how they actually compare.
Both are weekly injections that quiet appetite and slow digestion, but they are not identical. Semaglutide, sold as Wegovy and Ozempic, acts on one hormone pathway called GLP-1. Tirzepatide, sold as Zepbound and Mounjaro, acts on two pathways, GLP-1 and GIP, and that second pathway appears to give it an extra push.
In 2025 the New England Journal of Medicine published the first direct, head-to-head comparison of the two, a trial of 751 adults over 72 weeks. Tirzepatide led to an average weight loss of about 20 percent of body weight, compared with about 14 percent for semaglutide. Roughly one in three people on tirzepatide lost 25 percent or more of their body weight, compared with about one in six on semaglutide. It is worth being fair here: semaglutide’s results still far exceed anything possible with older weight-loss approaches.
| Semaglutide (Wegovy, Ozempic) | Tirzepatide (Zepbound, Mounjaro) | |
|---|---|---|
| How it works | One pathway (GLP-1) | Two pathways (GLP-1 and GIP) |
| Average weight loss in the head-to-head trial | About 14 percent | About 20 percent |
| Common side effects | More nausea and constipation | More diarrhea, with less nausea |
A few honest caveats. That head-to-head trial was funded by the maker of tirzepatide, so it should be read with that in mind, even though the result was clear. Side effect profiles differ, cost and insurance coverage differ, and individual response varies more than any average suggests. Neither drug is the right answer for every person.
In my practice, here is what I actually see. The best medication is the one you tolerate well and can stay on consistently, because the results come from staying the course, not from the first few weeks. Matching the drug, the dose, and the plan to you is the part that makes the difference.
If you are trying to decide between them, that is exactly what a consult is for. The next step is a visit where we look at your health, your goals, and your history, and choose the option that fits you best.
To Health and Wellness, Dr. Tallman