Ozempic vs Mounjaro vs Zepbound Calculator

In clinical trials, tirzepatide (Mounjaro/Zepbound) at its maximum dose of 15 mg produced an average of 22.5% body weight loss over 72 weeks (SURMOUNT-1), compared to semaglutide (Ozempic/Wegovy) at 2.4 mg which produced 14.9% loss over 68 weeks (STEP-1). Tirzepatide's dual GIP/GLP-1 mechanism appears to produce greater weight loss than GLP-1-only drugs. However, individual results vary widely, and the SURPASS-2 trial (the only head-to-head trial) compared tirzepatide to semaglutide 1 mg (not the maximum 2.4 mg weight-loss dose), so a direct max-dose comparison is not yet available from a single trial.

Mounjaro and Zepbound are the same drug (tirzepatide) manufactured by Eli Lilly. The only difference is the FDA-approved indication: Mounjaro for type 2 diabetes, Zepbound for chronic weight management in adults with BMI 30+ or BMI 27+ with at least one weight-related condition. The doses, injection schedule, and weight loss efficacy are identical.

GLP-1 receptor agonists mimic the incretin hormone GLP-1, which slows gastric emptying, reduces appetite, and increases satiety signals to the brain. Semaglutide (Ozempic) targets only the GLP-1 receptor. Tirzepatide (Mounjaro/Zepbound) is a dual agonist that also activates GIP receptors, which enhances insulin secretion, improves fat metabolism, and may increase energy expenditure. This dual mechanism is believed to explain the greater weight loss seen in tirzepatide trials.

Most people notice weight loss within 4-8 weeks. Semaglutide shows the most rapid weight loss between weeks 12-28, with diminishing returns beginning around week 40. Tirzepatide continues producing meaningful weight loss further into treatment, with the steepest decline between weeks 12-36 and gradual slowing after week 40-52. Both medications require gradual dose titration over the first 4-5 months, during which the primary goal is establishing tolerability.

Without insurance, Ozempic costs approximately $900-$1,350 per month, while Mounjaro and Zepbound each cost approximately $1,000-$1,200 per month. Both manufacturers offer savings programs for eligible commercially insured patients that can reduce costs to as low as $25/month. Medicare and Medicaid coverage for the weight-loss indication is limited. Check with your insurance provider for specific coverage details.

Yes. Ozempic projections use data from the STEP-1 trial (Wilding et al., NEJM 2021, N=1,961), which studied semaglutide 2.4 mg over 68 weeks. Mounjaro and Zepbound projections use data from the SURMOUNT-1 trial (Jastreboff et al., NEJM 2022, N=2,539), which studied tirzepatide 15 mg over 72 weeks. Weight loss curves are modeled as non-linear (logarithmic), reflecting the pattern observed in these trials where most weight loss occurs in the first 6-12 months with gradual plateau thereafter.