GLP-1 Weight Loss Trajectory Planner

Q: Why does tirzepatide outperform semaglutide in this calculator?

SURMOUNT-1 reported a higher mean loss (−20.9% at 72 weeks) than STEP 1 (−14.9% at 68 weeks). Direct comparisons (SURMOUNT-2 / SURPASS-2) also favor tirzepatide on average, likely because it agonizes both GIP and GLP-1 receptors. Trial populations differ slightly, so head-to-head conclusions remain imperfect.

Q: How accurate is the plateau prediction?

It is a trial-cohort average — the week at which the published slope falls below 0.2 percentage points per week. Real-world plateaus span 8 to 16 weeks around the predicted week, depending on adherence, dose, comorbidities, and lifestyle context.

Q: What if my starting weight is much higher or lower than the trial average?

Trial populations clustered around BMI 38 at baseline. Percent loss tends to scale roughly with starting body weight, but very low or very high starting weights are outside the data the calculator interpolates from.

Q: Does the dose tier multiplier reflect published data?

No published trial reports outcomes at each titration step in the format used here. The 0.55 (starting) and 0.80 (mid) multipliers are approximations consistent with published interim readouts and the published dose-response in SURMOUNT-1. Use them as a planning aid, not a prediction.

Q: Can I keep the weight off after stopping the medication?

STEP 4 randomized participants to continue or discontinue semaglutide. Continuers maintained loss; discontinuers regained roughly two-thirds of lost weight within a year. Tirzepatide discontinuation trends are similar. Treat GLP-1 therapy as chronic, not a temporary intervention.

Q: Is this medical advice?

No. This calculator estimates expected outcomes based on published clinical trial averages. It is not a substitute for evaluation by a licensed prescriber. Decisions about starting, adjusting, or stopping GLP-1 therapy require a clinician familiar with your full medical history.

Q: How does this differ from the simpler GLP-1 Weight Loss Projector?

The simpler projector only takes drug and current weight. This planner adds height (for BMI tracking), age, sex, dose tier, custom duration, and a user-supplied target — and returns plateau timing and cohort hit rate for that target.

This planner builds a full week-by-week expected trajectory for semaglutide (STEP 1), tirzepatide (SURMOUNT-1), or liraglutide (SCALE) — projecting expected weight, BMI category, plateau timing, and the share of the trial cohort that hit your target. Curves are scaled by your selected dose tier. Estimates are based on published clinical trial averages; your individual response may vary substantially. This is an informational estimator, not medical advice — discuss any therapy decisions with your prescriber.

Reviewed by GetHealthyCalculators Editorial Team · Updated May 14, 2026

Quick Answer

On the maintenance dose, mean trial data shows about −15% body weight at 68 weeks for semaglutide, −21% at 72 weeks for tirzepatide, and −8% at 56 weeks for liraglutide. Individual response varies — 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.

How the Formula Works

Compute starting BMI from height and weight.
BMI = weight(kg) / height(m)²
Read the published % weight loss milestones for the selected drug.
STEP 1 / SURMOUNT-1 / SCALE trajectory curve
Scale by dose tier multiplier (starting 0.55, mid 0.80, maintenance 1.0).
% loss(week) × dose multiplier
Apply each milestone % loss to starting weight to project expected weight & BMI.
Projected weight = Start × (1 − %loss/100)
Estimate plateau week (slope < 0.2 pp/week) and cohort hit rate vs. target.
Trial responder distribution lookup

Methodology & Sources

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

Milestone percent losses are transcribed from the published trajectory figures in the pivotal NEJM papers (STEP 1, SURMOUNT-1, SCALE). Intermediate weeks are linearly interpolated. Cohort hit rate is derived from the published responder distributions and scaled by dose tier. Plateau week is the first published readout where the trajectory slope falls below 0.2 percentage points per week.

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
Rubino D et al. Effect of Continued Weekly Semaglutide vs. Placebo on Weight Loss Maintenance. (STEP 4, 2021) · JAMA

Limitations

Mean values hide wide individual variation. Plan for a range: mean plus or minus roughly 10 percentage points.
Dose tier multipliers (starting 0.55, mid 0.80, maintenance 1.0) are approximations — published trials only report the full maintenance dose.
Trial participants received structured lifestyle counseling along with the medication.
Compounded or generic formulations may deliver different effective doses than the branded product.
Plateau timing is a population estimate; individual plateaus can vary by 8 to 16 weeks.
Discontinuation typically results in partial weight regain within 12 months.
This calculator is an estimator, not medical advice. Discuss any therapy decision with your prescriber.

Frequently Asked Questions

Why does tirzepatide outperform semaglutide in this calculator?

SURMOUNT-1 reported a higher mean loss (−20.9% at 72 weeks) than STEP 1 (−14.9% at 68 weeks). Direct comparisons (SURMOUNT-2 / SURPASS-2) also favor tirzepatide on average, likely because it agonizes both GIP and GLP-1 receptors. Trial populations differ slightly, so head-to-head conclusions remain imperfect.

How accurate is the plateau prediction?

It is a trial-cohort average — the week at which the published slope falls below 0.2 percentage points per week. Real-world plateaus span 8 to 16 weeks around the predicted week, depending on adherence, dose, comorbidities, and lifestyle context.

What if my starting weight is much higher or lower than the trial average?

Trial populations clustered around BMI 38 at baseline. Percent loss tends to scale roughly with starting body weight, but very low or very high starting weights are outside the data the calculator interpolates from.

Does the dose tier multiplier reflect published data?

No published trial reports outcomes at each titration step in the format used here. The 0.55 (starting) and 0.80 (mid) multipliers are approximations consistent with published interim readouts and the published dose-response in SURMOUNT-1. Use them as a planning aid, not a prediction.

Can I keep the weight off after stopping the medication?

STEP 4 randomized participants to continue or discontinue semaglutide. Continuers maintained loss; discontinuers regained roughly two-thirds of lost weight within a year. Tirzepatide discontinuation trends are similar. Treat GLP-1 therapy as chronic, not a temporary intervention.

Is this medical advice?

No. This calculator estimates expected outcomes based on published clinical trial averages. It is not a substitute for evaluation by a licensed prescriber. Decisions about starting, adjusting, or stopping GLP-1 therapy require a clinician familiar with your full medical history.

How does this differ from the simpler GLP-1 Weight Loss Projector?

The simpler projector only takes drug and current weight. This planner adds height (for BMI tracking), age, sex, dose tier, custom duration, and a user-supplied target — and returns plateau timing and cohort hit rate for that target.

Estimate your protein target to preserve muscle on therapy

GLP-1 Protein Calculator

GLP-1 Weight Loss Trajectory Planner

How the Formula Works

Methodology & Sources

References

Limitations

Frequently Asked Questions

Related Calculators

GLP-1 Weight Loss Projector

GLP-1 Eligibility Calculator

GLP-1 Dosage Schedule Calculator

GLP-1 Cost Calculator

GLP-1 Muscle Loss Risk Calculator

GLP-1 Protein Calculator

More on This Topic

GLP-1 Weight Loss Calculator

GLP-1 Calculator