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GLP-1 tool guide

How much weight can I lose on Mounjaro, Wegovy or Ozempic?

Written by Jude Bencia · Reviewed by Dr Himani Nayyar, BHMS · Updated

For people already prescribed GLP-1 medication. Weight Easy does not prescribe, sell or arrange medication; your prescriber is responsible for treatment decisions.

In brief

In the main trials, people lost an average of 15% to 21% of their body weight on tirzepatide (Mounjaro, Zepbound) over 72 weeks and about 15% on semaglutide 2.4 mg (Wegovy) over 68 weeks. People with type 2 diabetes lost less, about 9% to 15%. Enter your details to get your week-by-week projection in the free Weight Easy app.

Open the free GLP-1 Weight Loss Calculator →

What the trials found

These are average results from the trials used to approve each medicine, where participants also had diet and activity support. They are the most reliable numbers available, but your result can be higher or lower.

  • Tirzepatide 5 mg: 15.0% average loss at 72 weeks (SURMOUNT-1).
  • Tirzepatide 10 mg: 19.5% at 72 weeks (SURMOUNT-1).
  • Tirzepatide 15 mg: 20.9% at 72 weeks (SURMOUNT-1).
  • Semaglutide 2.4 mg (Wegovy): 14.9% at 68 weeks (STEP 1).
  • Semaglutide 7.2 mg (Wegovy high dose, sold as Wegovy HD in the US): 18.7% at 72 weeks (STEP UP).
  • With type 2 diabetes: 12.8% and 14.7% on tirzepatide 10 and 15 mg (SURMOUNT-2); 9.6% on semaglutide 2.4 mg and 7.0% on 1 mg (STEP 2).
  • Wegovy pill (oral semaglutide 25 mg): 13.6% at 64 weeks (OASIS 4).
  • Foundayo (orforglipron): 11.2% at 72 weeks on the highest dose in ATTAIN-1, which used a trial formulation (36 mg) equivalent to the 17.2 mg tablet.
  • Saxenda (liraglutide 3 mg): 8.0% at 56 weeks (SCALE), 6.0% with type 2 diabetes.
  • Yurpeak, compounded tirzepatide and generic or compounded semaglutide use the same molecule as the trials above, but these products were not themselves tested in them.
  • Trulicity, Victoza, Byetta, Bydureon BCise and Rybelsus are diabetes medicines with no weight-loss trial at a weight-management dose, so the calculator does not project them.

Why the first weeks feel slow

Weekly GLP-1 injections start at a low dose and usually step up every 4 weeks, so the first 2 to 3 months are mostly about getting used to the medicine. On average, loss builds steadily through the dose steps and continues for several months after you reach your maintenance dose, then slows and levels off after about a year. A slower first month is normal, not a sign the medicine is failing.

How to land on the better side of the average

Trial participants who did best tended to stay on treatment and keep up the basics:

  • Take every dose on schedule and step up only as your prescriber advises.
  • Eat enough protein every day to protect muscle while you lose fat.
  • Do strength training two or three times a week.
  • Track weight weekly, not daily, to see the real trend.

How this calculator works

We fit a smooth curve that starts at your weight and reaches the trial's average percentage loss at the trial's final week, following the shape of the published results. It is an estimate for planning and motivation, not a promise or medical advice.

Frequently asked questions

FAQ

How much weight can you lose on Mounjaro in a month?

In the first month most people are on the 2.5 mg starting dose and lose on average around 2% to 4% of their body weight. Loss usually continues over the following months as the dose increases.

How much weight can I lose on Wegovy in 3 months?

Using the STEP 1 average, about 6% to 7% of starting weight by week 12, with much of the loss coming later once you reach the 2.4 mg maintenance dose.

Is Mounjaro better than Wegovy for weight loss?

In the SURMOUNT-5 head-to-head trial in adults with obesity but without diabetes, tirzepatide led to 20.2% average weight loss versus 13.7% for semaglutide at 72 weeks. The best choice still depends on your health, side effects and access.

Why am I not losing weight on 2.5 mg of Mounjaro?

2.5 mg is a starting dose meant to help your body adjust, so many people lose little at first. Give it the full 4 weeks and track your weekly trend before judging.

Do people with diabetes lose less weight on GLP-1s?

Yes. In the trials, people with type 2 diabetes lost roughly a quarter to a third less on average than people without diabetes on the same medicine. The calculator adjusts for this.

Sources and limits

  • STEP 1, Wilding et al., NEJM 2021; STEP 2, Davies et al., Lancet 2021; STEP UP, Lancet Diabetes Endocrinol 2025.
  • SURMOUNT-1, Jastreboff et al., NEJM 2022; SURMOUNT-2, Garvey et al., Lancet 2023; SURMOUNT-5, NEJM 2025.

This guide is educational, not a diagnosis, prescription or dose-change instruction. Always follow your medication leaflet and clinician.