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GLP-1 Weight-Loss Timeline: Month-by-Month Projection from the Tirzepatide and Semaglutide Trials

See the expected shape of weight loss over 72 weeks on tirzepatide or 68 weeks on semaglutide, based on the SURMOUNT-1 and STEP 1 trajectories, applied to your starting weight.

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Enter your starting weight.

The shape of the curve

Weight loss on a GLP-1 is not linear. During titration (the first 16-20 weeks), doses are low and loss is modest. Loss accelerates after reaching the maintenance dose and then slows as the body reaches a new balance. The tool draws that curve for your starting weight using the published trial trajectories: SURMOUNT-1 for tirzepatide 15 mg and STEP 1 for semaglutide 2.4 mg.

Why individual timelines differ

Titration speed (some clinicians go slower than the label to manage nausea), adherence, diet and activity, baseline weight, and diabetes status all shift the curve. The trial trajectories are averages of a population that received lifestyle counseling throughout. Use the tool to understand what a typical course looks like and when to expect a plateau, not as a promise. Our plateau guide covers what to do when the curve flattens.

Frequently asked questions

When does weight loss start on a GLP-1?

In the trials, mean loss was about 4-6% by week 12 during titration, roughly 10-12% by week 24, and continued to slow through weeks 48-72. Most of the effect arrives after reaching the maintenance dose.

When does weight loss plateau?

Trial curves flatten between weeks 48 and 72; most participants reached a plateau by about a year at the maintenance dose. A plateau is expected and reflects a new energy balance, not treatment failure.

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Plan prices verified against nexlife.us on August 25, 2026. Stated values are NexLife's own. Our commercial relationship with NexLife is disclosed; rankings on this site are computed from data, not from this placement.

Included with treatment at no extra cost

  • Provider review and ongoing medical guidance$199Included
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NexLife plan pages

Regular protocol Standard injectable plans; the ones our rankings use
Semaglutide →Tirzepatide →
Microdose protocol Lower-dose plans; listed in our database, not ranked
Tirzepatide →Semaglutide →
Sublingual (ODT) protocol Orally disintegrating tablets; listed, not ranked
Tirzepatide →Semaglutide →