Project your weight trajectory based on published Phase 3 trial means. Individual response varies significantly.

Medication & dose

Starting weight

Unit

Projected outcome at trial endpoint (~70 weeks)

Mean weight loss: —

Projected end weight: —

These projections use trial-mean responses. Individual outcomes vary widely — some patients lose more, some lose less. This is not medical advice; consult a clinician for personalized expectations.

Phase 3 trials publish mean weight-loss percentages at fixed time points. This tool applies those means to your starting weight to project your end weight if you respond like the average patient. Real outcomes vary widely.

Trial reference

Wegovy 2.4 mg (semaglutide): STEP-1 trial reported ~14.9% mean body-weight reduction at 68 weeks.
Zepbound 5 mg (tirzepatide): SURMOUNT-1 reported ~15.0% at 72 weeks.
Zepbound 10 mg: ~19.8% at 72 weeks.
Zepbound 15 mg (max dose): ~22.5% at 72 weeks.

These are mean responses. Some patients lose substantially more (super-responders), others lose less (sub-responders). Adherence, lifestyle factors, and individual biology all affect outcome.

How the projection works

The calculator applies trial-mean percentage weight loss to your starting weight. Trial means come from FDA-published trial summaries:

STEP-1 (Wegovy 2.4 mg, 68 weeks): -14.9% mean body weight reduction
SURMOUNT-1 (Zepbound 5 mg, 72 weeks): -15.0%
SURMOUNT-1 (Zepbound 10 mg, 72 weeks): -19.5%
SURMOUNT-1 (Zepbound 15 mg, 72 weeks): -20.9%
SURMOUNT-5 (head-to-head, 72 weeks): Tirzepatide 20.2% vs Semaglutide 13.7%

These are mean responses. About 30% of patients exceed the mean (super-responders); about 30% lose less (sub-responders). Adherence, lifestyle factors, baseline insulin sensitivity, and individual biology all affect outcome.

How patients use this tool

Goal-setting: Project a realistic 12-month or 18-month weight target.
Medication choice: Compare projected outcomes for semaglutide vs tirzepatide.
Dose-decision support: Compare projections at different tirzepatide doses.
Expectation-setting: Understand that 15-20% weight loss is the typical 1-year outcome.

Frequently asked questions

Why doesn't the calculator account for individual variation?

Individual variation is large and not predictable from baseline characteristics. The calculator gives you the trial mean — your individual outcome may be substantially better or worse. After 3-6 months on therapy, you'll have data on your personal response trajectory.

What predicts being a super-responder?

Predictors are limited. Baseline insulin sensitivity, adherence, sleep quality, and resistance training are partial predictors. Lower baseline BMI is associated with smaller absolute weight loss but similar percentage loss.

Will I keep losing weight after 72 weeks?

The pace of weight loss decelerates after 6-9 months and approaches a new equilibrium around 12-18 months. STEP-5 and SURMOUNT-2 trials show continued (slower) weight loss out to 2 years for many patients.

What happens if I stop?

STEP-4 and SURMOUNT-4 trial data show patients regain roughly two-thirds of lost weight within 12-18 months of discontinuation. See our stopping GLP-1 guide.

Other free tools

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