Weight loss projection calculator realistic 12-month outcomes on Ozempic/Wegovy/Mounjaro

The Health Desk · Editorial team, aged care + dental + plastic surgery + dermatology + weight-loss + psychology · Updated 14 May 2026 · How we rank · Editorial standards

Marketing weight-loss stories are unreliable signals. Clinical trial averages are more useful. This calculator uses STEP-1 (Wegovy), SURMOUNT-1 (Mounjaro), and STEP data (Ozempic) to give you a realistic 12 and 24-month projection range. Includes confidence intervals so you know where you might land.

★Key takeaways

  • ✓Wegovy: ~15% body weight loss at 68 weeks (STEP-1 average).
  • ✓Mounjaro: ~20% body weight loss at 72 weeks (SURMOUNT-1, 15mg dose).
  • ✓Off-label Ozempic: ~10-12% body weight loss (capped at 1.0mg dose).
  • ✓5-10% of patients are non-responders. 15-20% are super-responders.
  • ✓Plateau typically at 12-18 months; sustained loss requires continued therapy.

Run your projection

Realistic projection range

Lose 0 kg

at average response, over 12 months

Low responder

-0 kg

~10% of patients

Average

-0 kg

~70% in this range

Super responder

-0 kg

~20% of patients

Final weight: 0 kg (average response from 0 kg start).

Based on STEP-1 (Wegovy), SURMOUNT-1 (Mounjaro), and STEP trial data for off-label Ozempic. Individual results vary significantly. Resistance training + 1.2-1.6g/kg protein intake supports better outcomes. See our muscle preservation guide.

Where the trial numbers come from

The projection uses three landmark trial datasets:

  • STEP-1 (Wegovy 2.4mg, NEJM 2021): 68-week trial showing approximately 14.9% body weight loss with semaglutide 2.4mg vs 2.4% placebo. ~1,961 participants.
  • SURMOUNT-1 (Mounjaro 15mg, NEJM 2022): 72-week trial showing approximately 20.9% body weight loss with tirzepatide 15mg vs 3.1% placebo. ~2,539 participants.
  • STEP trials (Ozempic 1mg): Modelled from STEP data extrapolated to the lower 1.0mg dose. Achievable weight loss is typically 10-12% based on dose-response relationships in the underlying data.

The "low responder" and "super responder" ranges reflect the confidence intervals in the trial data. About 10% of trial participants achieved less than 5% weight loss; about 20% achieved more than 20%.

What the projection does NOT account for

  • Age. Older patients (60+) sometimes see slower responses; metabolic adaptations differ.
  • Hormonal status. Women with PCOS or significant insulin resistance can respond differently (sometimes much better).
  • Baseline activity level. Sedentary baseline patients have more room for adjunctive lifestyle gain.
  • Medication adherence. Trial patients had structured adherence support; real-world adherence is lower.
  • Comorbid medications. Some medications (steroids, certain antipsychotics, beta-blockers) suppress weight loss response.

What to do with this projection

  • Set realistic expectations. The number on the calculator is what trials show, not what social media promises.
  • Plan your treatment horizon. Most weight loss happens in months 2-12; plan to commit at minimum 12 months.
  • Calculate cost vs benefit. Combine this projection with our cost calculator to see the cost per kg lost.
  • Discuss with your prescriber. Bring the projection to your initial consultation as a starting point for goal-setting.
  • Plan for muscle preservation. Without resistance training + protein, around 30% of the projected weight loss will be muscle. See our muscle preservation guide.

Related coverage

Common questions

Weight loss projection: frequently asked questions

How accurate are these projections?

The calculator uses average and confidence interval data from published clinical trials (STEP-1 for Wegovy, SURMOUNT-1 for Mounjaro, STEP trials for off-label Ozempic). Individual responses vary significantly. Around 15-20% of patients are "super-responders" who exceed average; around 5-10% are non-responders with minimal weight loss. The projections give a realistic middle range.

Why is the projected weight loss less than what I see in social media stories?

Social media skews toward super-responders and early enthusiasm. Average trial data is more representative. Patients losing 25-30% of body weight in 6 months are real but not typical. The calculator gives the middle of the bell curve, not the extreme tail.

What if I am older / female / have hormonal issues?

Trial data adjusts for these factors but individual variation is large. Older patients, women with PCOS or hormonal issues, and patients with severe insulin resistance can all see different responses (sometimes better, sometimes worse). Treat the projection as a starting point for discussion with your prescriber.

Does this account for diet and exercise?

The trial data this is based on included standard lifestyle counselling. Patients with rigorous diet/training will exceed projections; sedentary patients with no dietary change will fall short. The projection assumes "average" lifestyle effort, which is what trial participants achieved.

What happens at the plateau in the projection?

Around month 12-18, most patients reach a plateau where the body adapts to the new equilibrium. Continued therapy maintains the weight loss; discontinuation leads to regain. The projection extends to 24 months but the rate slows substantially after month 12.