Weight Loss Projector
A 12-month projection curve built from the clinical trials.
Projected at 12 months
180lb
Total lost
−40lb
≈ 18.4% of body weight
Based on the mean total weight loss reported in SURMOUNT-1 (20.9% on Tirzepatide 15mg). Trial averages hide huge individual variation — your curve depends on dose, diet, muscle, and consistency. This is an educational estimate, not a promise.
What the trials actually showed
The headline numbers come from two landmark trials. In STEP 1, adults on semaglutide 2.4 mg lost an average of ~14.9% of body weight over 68 weeks. In SURMOUNT-1, tirzepatide 15 mg produced ~20.9% over 72 weeks. Those are averages at the maximum maintenance dose, after full titration.
Why your curve bends, not spikes
Weight loss on GLP-1s is front-loaded: the biggest drops come in the first few months, then the rate eases as your body approaches a new set point. That's why this projector uses a curve that rises quickly and flattens, rather than a straight line. A plateau isn't failure — it's the expected shape.
The honest caveat
Trial averages hide enormous individual variation. Some people well exceed the mean; others land below it. Your real trajectory depends on your starting weight, dose, diet (especially protein), muscle mass, activity, and consistency. Treat this as an educational estimate to set expectations, never a personal guarantee — and track your real numbers as you go.
Frequently asked
- How much weight can you lose on tirzepatide or semaglutide?
- In trials, average total body-weight loss reached about 20.9% on tirzepatide 15 mg (SURMOUNT-1) and 14.9% on semaglutide 2.4 mg (STEP 1). Individual results vary widely around those averages.
- How fast does GLP-1 weight loss happen?
- It is front-loaded. The steepest loss is usually in the first few months, then it slows as you approach a new set point. Most trials ran 15–18 months to reach the averages above.
- Is this projection a guarantee of my results?
- No. It reshapes clinical-trial averages into a curve for your starting weight to set expectations. Your actual outcome depends on dose, diet, muscle, activity, and consistency, and can land well above or below the average.
- Why did my weight loss plateau?
- Plateaus are expected as your body reaches a new equilibrium. Protein intake, resistance training, sleep, and dose can all influence when it happens. A stall in scale weight does not mean body composition has stopped improving.
Related calculators
- Vial Transition Dosage CalculatorSwitching vial strengths? Keep the same dose, new units.
- GLP-1 Cost per Pound CalculatorWhat each pound is really costing you in medication.
- GLP-1 Plotter: Tirzepatide & Semaglutide LevelsWatch your level build to steady state — and how long the ladder takes.
- GLP-1 Protein Calculator for Zepbound & WegovyYour daily protein floor — and which body weight the g/kg actually applies to.
Read next
- What to do when Ozempic weight loss stallsStalled on Ozempic? A prioritised, trackable plateau plan: protein floor, injection-site rotation, dose check with your prescriber, and the non-scale trend.
- Rebound weight gain after stopping OzempicHow much weight comes back after stopping a GLP-1, why it happens, and why regaining the number doesn't mean regaining the same body composition.
- Zepbound vs Wegovy and the muscle questionDoes Zepbound or Wegovy cost more muscle? What the trials show, your protein floor (1.2–1.6 g/kg), and how to measure lean mass without the scale.
Sources
- Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity — STEP 1: mean −14.9% at week 68 versus −2.4% on placebo, N=1961
- Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity — SURMOUNT-1: −15.0%, −19.5% and −20.9% at 5, 10 and 15 mg over 72 weeks, N=2539
- Aronne LJ, et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity — SURMOUNT-5 head-to-head: −20.2% versus −13.7% at week 72
Medical disclaimer. Tiro is a tracking companion, not a medical device, and nothing on this site is medical advice. Always follow the titration schedule and dosing instructions from your prescriber. Never change your dose without talking to them first.