Semaglutide vs. Tirzepatide: Comparing the Research
Both semaglutide and tirzepatide are medications our physicians may consider for an appetite programme. Each has published Phase 3 trial data from the New England Journal of Medicine. This article presents that data side by side so you can understand what the research shows — not to recommend one over the other, which is your doctor's determination. Individual results vary.
The Source Studies
This comparison draws only from the two peer-reviewed sources below. All numbers cited are from these publications.
- Wilding JPH et al. "Once-Weekly Semaglutide in Adults with Overweight or Obesity." NEJM. 2021;384:989–1002. (STEP 1 trial)
https://www.nejm.org/doi/10.1056/NEJMoa2032183 - Jastreboff AM et al. "Tirzepatide Once Weekly for the Treatment of Obesity." NEJM. 2022;387:205–216. (SURMOUNT-1 trial)
https://www.nejm.org/doi/10.1056/NEJMoa2206038
Side-by-Side: Trial Design
| Factor | Semaglutide (STEP 1) | Tirzepatide (SURMOUNT-1) |
|---|---|---|
| Published | NEJM, 2021 | NEJM, 2022 |
| Trial duration | 68 weeks | 72 weeks |
| Participants | 1,961 adults | 2,539 adults |
| Mechanism | GLP-1 receptor agonist | Dual GIP + GLP-1 receptor agonist |
| Administration | Once-weekly injection (2.4 mg) | Once-weekly injection (5, 10, or 15 mg) |
| T2D excluded? | Yes (in STEP 1) | Yes (in SURMOUNT-1) |
| Lifestyle intervention | Yes (all participants) | Yes (all participants) |
Side-by-Side: Mean Weight Reduction
Individual results vary. All figures are from the cited NEJM trials.
| Group | Mean weight reduction from baseline | Source |
|---|---|---|
| Semaglutide 2.4 mg | 14.9% | Wilding et al., NEJM 2021 |
| Placebo (STEP 1) | 2.4% | Wilding et al., NEJM 2021 |
| Tirzepatide 5 mg | 15.0% | Jastreboff et al., NEJM 2022 |
| Tirzepatide 10 mg | 19.5% | Jastreboff et al., NEJM 2022 |
| Tirzepatide 15 mg | 20.9% | Jastreboff et al., NEJM 2022 |
| Placebo (SURMOUNT-1) | 3.1% | Jastreboff et al., NEJM 2022 |
Important Caveats for Interpreting This Comparison
These two trials were conducted independently, in different years, with different participant populations and slightly different trial durations. A direct head-to-head comparison between semaglutide and tirzepatide would require a study that randomised participants to both agents simultaneously — which the STEP 1 and SURMOUNT-1 trials did not do. The figures above are reported trial outcomes, not a controlled comparison of one drug against the other. Individual results vary.
What This Means for Your Programme
Your Bunny physician reviews your individual health profile and determines which medication — if any — is appropriate for you. The doctor makes this decision; Bunny does not have a default protocol. You will discuss your options during your consultation.
Related Articles
- How GLP-1 Medications Work
- Semaglutide: What the Clinical Trials Show
- Tirzepatide: What the Clinical Trials Show
- GLP-1 Side Effects: What the Research Says
- Who May Be a Candidate for Medical Weight Loss
All medical decisions are made solely by licensed healthcare professionals. Medications are prescribed only when medically necessary. GLP-1 medications are not suitable for everyone. Results may vary.
Results vary. Clinical trial results apply only to the FDA-approved branded medication specifically identified and do not apply to compounded medications. All medications must be prescribed by a licensed provider based on medical necessity.