How Long Does It Take to Lose 40 Pounds on a GLP-1?
Short answer: using average results from published clinical trials, losing 40 pounds takes 11 to 24+ months on semaglutide and 6 to 24+ months on tirzepatide, depending on your starting weight. Someone starting at 200 pounds and aiming for 160 would need to lose 20% of their body weight, which our model projects at 24+ months on semaglutide and 21 months on tirzepatide.
Estimated time to lose 40 pounds by starting weight
| Start | Goal | % of body weight | Semaglutide | Tirzepatide |
|---|---|---|---|---|
| 160 lbs | 120 lbs | 25% | 24+ months | 24+ months |
| 180 lbs | 140 lbs | 22.2% | 24+ months | 24+ months |
| 200 lbs | 160 lbs | 20% | 24+ months | 21 months |
| 220 lbs | 180 lbs | 18.2% | 24+ months | 14 months |
| 250 lbs | 210 lbs | 16% | 24+ months | 10 months |
| 300 lbs | 260 lbs | 13.3% | 17 months | 7 months |
| 350 lbs | 310 lbs | 11.4% | 11 months | 6 months |
"24+ months" means the goal is not reached within the 24-month window our model covers. Estimates use the average outcomes from the STEP 1 (semaglutide) and SURMOUNT-1 (tirzepatide) trials and are not a prediction for any individual.
Why the same 40 pounds takes different amounts of time
Trial results are reported as a percentage of starting body weight, not a fixed number of pounds. Losing 40 pounds is a smaller share of body weight for someone who starts heavier, so it can be reached sooner, while the same 40 pounds is a much bigger share for someone lighter. Loss is also fastest early on and slows as it approaches a plateau, so the last few pounds take disproportionately longer.
Get your own estimate
The table uses round starting weights. Enter your exact current weight and goal weight in the calculator to see a month-by-month timeline for both medications.
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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.