Semaglutide vs. Tirzepatide: What the Trials Show
Short answer: in published clinical trials, tirzepatide produced a larger average total body-weight reduction than semaglutide, 20.9% at 72 weeks (SURMOUNT-1, highest studied dose) versus 14.9% at 68 weeks (STEP 1). These are trial averages across study populations, not a guarantee of what any individual will experience.
The trial numbers
| Medication | Trial | Duration | Avg. weight reduction |
|---|---|---|---|
| Semaglutide | STEP 1 | 68 weeks | ~14.9% |
| Tirzepatide | SURMOUNT-1 (highest dose) | 72 weeks | ~20.9% |
Why the numbers differ
Semaglutide is a GLP-1 receptor agonist. Tirzepatide acts on both the GLP-1 and GIP receptors, a dual mechanism that trial data associates with greater average weight reduction. Individual response depends on many factors beyond the medication itself, including dosage, diet, activity level, and adherence.
What this means for your own timeline
Trial averages describe a study population, not any one person. Our calculator applies these published averages to your specific starting weight and goal weight to estimate a personalized month-by-month timeline for each medication.
See how these averages apply to your own numbers.
Try the Free GLP-1 CalculatorMedical Disclaimer
This calculator is for educational and informational purposes only and does not provide medical advice, diagnose any condition, recommend or prescribe treatment, or guarantee results. Estimates are based on information you provide and published clinical-trial averages. Individual results can vary significantly.
Estimates are based on average outcomes reported in the STEP 1 (semaglutide) and SURMOUNT-1 (tirzepatide) clinical trials. Individual results can vary significantly and are influenced by factors such as dosage, diet, and adherence.
Do not start, stop, or change any medication based on the results of this calculator. Always consult a qualified healthcare professional regarding medications, treatment options, risks, side effects, and your individual health needs.