GLP-1 Weight Loss Calculator

Project expected weight loss on Wegovy, Zepbound, Ozempic, Saxenda, or Mounjaro from your starting weight, based on pivotal clinical trial averages at 3, 6, 12, and 18 months.

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207.02 lbs

3 months

−12.98 lbs (5.9%)

197.34 lbs

6 months

−22.66 lbs (10.3%)

189.64 lbs

12 months

−30.36 lbs (13.8%)

187.22 lbs

18 months

−32.78 lbs (14.9%)

TimepointWeight lostProjected weight% lost
3 months12.98 lbs207.02 lbs5.9%
6 months22.66 lbs197.34 lbs10.3%
12 months30.36 lbs189.64 lbs13.8%
18 months32.78 lbs187.22 lbs14.9%
Based on Wegovy trial data Clinical trial averages. Roughly 50% of participants lose more than the median; about 15–20% are non-responders. Individual results depend on diet, activity, and adherence. Source: STEP 1 (Wilding et al., NEJM 2021).

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GLP-1 Weight Loss

GLP-1 Weight Loss Calculator — Wegovy, Zepbound, Ozempic weight loss projections

GLP-1 receptor agonists — including semaglutide (Wegovy, Ozempic), tirzepatide (Zepbound, Mounjaro), and liraglutide (Saxenda) — produce clinically significant weight loss. This GLP-1 weight loss calculator projects expected weight loss at 3, 6, 12, and 18 months based on published pivotal trial averages for each medication.

How much weight will I lose on Ozempic or Wegovy?

Clinical trial data gives the best available estimate. Wegovy (semaglutide 2.4 mg) produced mean weight loss of ~14.9% of body weight at 68 weeks in the STEP 1 trial. For a 250 lb (113 kg) person, that is approximately 37 lbs (17 kg) lost. Zepbound (tirzepatide 15 mg) showed ~20.9% weight loss at 72 weeks in SURMOUNT-1, the highest recorded in a pivotal GLP-1 trial.

Ozempic (semaglutide 0.5–2 mg, approved for type 2 diabetes) produced smaller losses — around 5–6% — because it uses lower doses than Wegovy. Saxenda (liraglutide 3 mg/day) produced ~8% in the SCALE trial. Results depend on dose adherence, dietary changes, and baseline weight.

Why trial averages may not reflect your result

About 15–20% of GLP-1 users are non-responders who lose less than 5% of body weight even at full dose. Conversely, roughly half of trial participants lost more than the median. Trial populations also followed structured diet and exercise counselling; real-world results vary.

Individual factors influencing response include the specific drug and dose reached, duration of treatment, dietary quality, physical activity level, metabolic health, sleep, stress, and genetic variability in GLP-1 receptor sensitivity.

Frequently asked questions

Which GLP-1 causes the most weight loss?

Zepbound / Mounjaro (tirzepatide) has shown the highest mean weight loss (~20.9% at 72 weeks at 15 mg) in pivotal trials. Wegovy (semaglutide 2.4 mg) showed ~14.9% at 68 weeks. Direct head-to-head comparisons are limited.

 How long does it take to see weight loss on GLP-1?

Most patients begin losing weight within the first 4–8 weeks. However, titration to the maintenance dose takes 4–20 weeks depending on the medication. The majority of weight loss in trials occurred in the first 12 months.

 Do you regain weight when you stop GLP-1 medication?

Clinical trials consistently show weight regain after stopping GLP-1 therapy. In STEP 1 extension, participants regained ~two-thirds of lost weight within 1 year of stopping Wegovy. Most guidelines consider GLP-1 therapy a long-term treatment.

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