How Long Does It Take to Lose 20 Pounds on a GLP-1?
Short answer: using average results from published clinical trials, losing 20 pounds takes 4 to 14 months on semaglutide and 3 to 6 months on tirzepatide, depending on your starting weight. Someone starting at 200 pounds and aiming for 180 would need to lose 10% of their body weight, which our model projects at 9 months on semaglutide and 5 months on tirzepatide.
Estimated time to lose 20 pounds by starting weight
| Start | Goal | % of body weight | Semaglutide | Tirzepatide |
|---|---|---|---|---|
| 160 lbs | 140 lbs | 12.5% | 14 months | 6 months |
| 180 lbs | 160 lbs | 11.1% | 10 months | 5 months |
| 200 lbs | 180 lbs | 10% | 9 months | 5 months |
| 220 lbs | 200 lbs | 9.1% | 7 months | 4 months |
| 250 lbs | 230 lbs | 8% | 6 months | 4 months |
| 300 lbs | 280 lbs | 6.7% | 5 months | 3 months |
| 350 lbs | 330 lbs | 5.7% | 4 months | 3 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 20 pounds takes different amounts of time
Trial results are reported as a percentage of starting body weight, not a fixed number of pounds. Losing 20 pounds is a smaller share of body weight for someone who starts heavier, so it can be reached sooner, while the same 20 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.