There is a direct trial—and a precise question
In SURMOUNT-5, tirzepatide produced a greater mean reduction in body weight than the semaglutide regimen studied at 72 weeks in adults with obesity without type 2 diabetes. That is a real randomized comparison. It is also narrower than saying one molecule is best for every person, indication or formulation.
First separate the names. Tirzepatide acts at GIP and GLP-1 receptors and is sold in the US as Mounjaro and Zepbound. Semaglutide acts at GLP-1 receptors and appears in Ozempic and Wegovy products. A receptor description explains a mechanism; it does not, by itself, settle treatment selection.
Molecules do not replace the product label
| Molecule | Brands | Why the exact product matters |
|---|---|---|
| Tirzepatide | Mounjaro; Zepbound | Labeled populations and uses differ between brands. |
| Semaglutide | Ozempic; Wegovy | Current labeling includes oral and injectable products with different indication details. |
For example, Mounjaro’s current label includes type 2 diabetes glycemic control and a cardiovascular indication, while Zepbound has adult weight-management and obstructive-sleep-apnea uses in specified populations. Ozempic is not simply another name for the entire semaglutide family. Our brand-specific comparisons unpack those distinctions.
Read SURMOUNT-5 on its own terms
| Study detail | What was studied |
|---|---|
| Design | Randomized, open-label phase 3b; 751 adults with obesity without type 2 diabetes. |
| Duration | 72 weeks. |
| Study regimens | Maximum-tolerated weekly tirzepatide 10/15 mg versus semaglutide 1.7/2.4 mg. These describe trial methods, not instructions for readers. |
| Tirzepatide mean weight change | −20.2%; 95% confidence interval −21.4 to −19.1. |
| Semaglutide mean weight change | −13.7%; 95% confidence interval −14.9 to −12.6. |
| Comparison | P< 0.001 for the reported weight comparison. |
The difference between those reported mean changes is 6.5 percentage points by arithmetic. It is not 6.5 kilograms, and a group mean is not a forecast for an individual. Open-label means participants and investigators knew the assigned treatment.
What the result does and does not cover
The study directly compared the specified injectable regimens in its enrolled population. It did not compare every current oral or injectable semaglutide presentation, every dose, or people with every combination of medical conditions. A diabetes-focused question may require different evidence.
The primary abstract reports gastrointestinal events as the most common adverse events, generally mild or moderate and mainly during escalation. The abstract does not provide enough detail here to reproduce a complete discontinuation or serious-event comparison. The short abstract is not a complete comparative safety assessment.
Each product has important contraindications, warnings and interactions, including a boxed warning concerning thyroid C-cell tumors. The actual Medication Guide and a person’s medical circumstances matter alongside an efficacy endpoint. More average weight reduction in one study is one part of a broader clinical decision.
Bring a specific question to the appointment
- Which condition and treatment goal are we addressing?
- Which exact brand, route and presentation are being considered?
- How closely does the relevant study population match my situation?
- What monitoring, tolerability and routine considerations matter for me?
Save the name of the study as well as the headline. “SURMOUNT-5, adults with obesity without diabetes, 72 weeks” is much more informative than a screenshot of a percentage with no comparator. A prescriber can then connect the evidence with the person and the current product label.
Read next
Sources and method
- Aronne et al., SURMOUNT-5, NEJM 2025 — primary abstract reviewed; DOI 10.1056/NEJMoa 2416394. Full journal text/appendix unavailable in the sources reviewed. Lilly funded.
- Mounjaro prescribing information, August 2026 — current glycemic and cardiovascular indications.
- Zepbound prescribing information, August 2026 — adult weight-management/OSA indications and current presentations.
- Ozempic injection prescribing information, May 2026 — sections 1, 3, 12.1 and Medication Guide.
- Ozempic tablets / Rybelsus prescribing information, January 2026 — oral semaglutide instructions and formulation distinctions.
- Wegovy prescribing information, June 2026 — injection/tablet indications and presentation-specific instructions.
Sources checked October 29, 2026.
Prepared by GLP Finds with AI-assisted writing and checked against the listed sources. Our editorial process. This article has not received independent clinical review.