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GLP-1 Weight Loss Projector

Published pivotal trials give a realistic picture of what average weight loss looks like on each GLP-1 drug: STEP 1 showed −14.9% at 68 weeks for semaglutide 2.4 mg, SURMOUNT-1 showed −20.9% at 72 weeks for tirzepatide 15 mg, and SCALE showed −8.0% at 56 weeks for liraglutide 3.0 mg. This calculator applies those published trajectory curves to your current weight so you can see milestone-by-milestone projections. Individual response varies — about ±10 percentage points around the mean.

Reviewed by GetHealthyCalculators Editorial Team · Updated April 14, 2026

Quick Answer

On mean trial data, a 220 lb adult on semaglutide can expect about −33 lb at 68 weeks; on tirzepatide, about −46 lb at 72 weeks; on liraglutide, about −18 lb at 56 weeks. These are mean values — about a third of participants lose substantially more, a third substantially less.

These results are estimates based on general formulas and are not a substitute for professional medical advice. Consult a healthcare provider before making health decisions.

GLP-1 medication

Set a shorter horizon to see early-trial checkpoints.

How the Formula Works

  1. Select the drug you plan to take.

    Drug: semaglutide | tirzepatide | liraglutide

  2. Read the published % weight loss milestone for the selected week horizon.

    Read %loss(week) from trial curve

  3. Apply to your current weight.

    Projected weight = Current x (1 - %loss/100)

  4. Interpolate between published milestones for intermediate weeks.

    Linear interpolation between readouts

Methodology & Sources

Reviewed and updated April 14, 2026 · Prepared by GetHealthyCalculators Editorial Team

Milestone percent losses are transcribed from the published trajectory figures in the pivotal NEJM papers. Intermediate weeks are linearly interpolated, which closely matches the published curves for semaglutide and tirzepatide and slightly underestimates late-trial loss for liraglutide.

References

  • Wilding JPH et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. (STEP 1, 2021) · New England Journal of Medicine
  • Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity. (SURMOUNT-1, 2022) · New England Journal of Medicine
  • Pi-Sunyer X et al. A Randomized, Controlled Trial of 3.0 mg of Liraglutide in Weight Management. (SCALE Obesity, 2015) · New England Journal of Medicine

Limitations

  • Mean values hide wide individual variation. Plan for a range: mean plus or minus about 10 percentage points.
  • Trial participants received lifestyle counseling in addition to the drug.
  • Compounded versions may deliver different effective doses than the branded drug; published data does not cover them.
  • Discontinuation typically results in partial weight regain within 12 months.

Frequently Asked Questions

Why does tirzepatide seem to outperform semaglutide?
SURMOUNT-1 was conducted later with a different patient population, so head-to-head comparisons are imperfect. But the SURMOUNT-2 and SURPASS-2 direct comparisons do suggest tirzepatide produces more weight loss on average, likely because it agonizes both GIP and GLP-1 receptors.
What if I plateau early?
Most responders see continued loss through the trial endpoint, but the slope flattens in the second half. An early plateau (first 12 weeks) is sometimes addressed by ensuring full titration or checking for weight-gain-inducing medications, diet drift, or reduced activity.
Do I keep the weight off?
STEP 4 randomized participants to continue or discontinue semaglutide. Continuers kept the loss; discontinuers regained ~two-thirds of it within a year. Tirzepatide discontinuation data shows a similar pattern. Treat GLP-1s as chronic therapy, not a temporary intervention.
Is the projection the same for Mounjaro as Zepbound?
The same molecule is used for both, at the same doses. The weight-loss data comes from SURMOUNT-1 (Zepbound-labeled indication). The type 2 diabetes SURPASS trials showed smaller mean loss because the population had different baseline characteristics.

Check eligibility criteria for each GLP-1 drug

GLP-1 Eligibility Calculator

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