GLP-1 Weight Loss Calculator
Estimate your projected weight loss on GLP-1 medications like Ozempic, Wegovy, Mounjaro, and Zepbound. Week-by-week projections based on clinical trial data. 100% private — nothing leaves your browser.
How GLP-1 Medications Work for Weight Loss
GLP-1 receptor agonists like semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) work by mimicking the natural incretin hormone GLP-1. They slow gastric emptying, reduce appetite, and improve insulin sensitivity. These medications signal the brain's satiety centers, helping patients feel full with smaller meals. Originally developed for type 2 diabetes, their weight loss effects have made them among the most prescribed medications worldwide. Clinical trials consistently show significant and sustained weight reduction when combined with lifestyle changes.
Ozempic vs Wegovy vs Mounjaro Compared
Ozempic (semaglutide up to 1.0mg) is FDA-approved for diabetes but widely used off-label for weight loss, producing around 10% body weight reduction. Wegovy delivers the same molecule at a higher dose (2.4mg), approved specifically for weight management with ~15% loss in the STEP 1 trial over 68 weeks. Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist — the SURMOUNT-1 trial showed up to 22.5% weight loss at the 15mg dose over 72 weeks, making it the most effective option currently available. Zepbound is the weight-management branded version of tirzepatide. Oral semaglutide 50mg (Wegovy pill) offers similar efficacy to injectable Wegovy in a daily tablet form.
What to Expect Week by Week on GLP-1
Weight loss on GLP-1 medications follows a logarithmic pattern — faster in the first few months, then gradually slowing as you approach your plateau. Most patients notice reduced appetite within the first 1-2 weeks. Significant scale changes typically appear by week 4-8. The dose titration schedule means you start low and increase gradually, so early weight loss may be modest. Peak weight loss velocity usually occurs between months 3 and 6, with most of the total loss achieved by month 12-16. Maintaining results requires ongoing treatment — studies show patients who discontinue often regain 50-70% of lost weight within a year.
Nutrition Tips While on GLP-1 Medication
Protein intake is critical during GLP-1 treatment. Rapid weight loss can lead to muscle loss, so aim for 1.2 to 1.6 grams of protein per kilogram of body weight daily. Prioritize lean meats, fish, eggs, Greek yogurt, and legumes. Eat protein first at each meal before carbohydrates and fats. Stay well-hydrated — these medications can cause dehydration. Eat slowly and stop at the first sign of fullness. Avoid high-fat and greasy foods which can worsen gastrointestinal side effects. A moderate calorie deficit of around 500 calories below your TDEE, combined with the appetite-suppressing effect of GLP-1, produces optimal results without excessive muscle loss.
Understanding Your Projected Results
This calculator uses a logarithmic decay model calibrated against published clinical trial outcomes. The formula accounts for medication type, dose, and treatment duration. Real-world results vary based on adherence, diet quality, exercise habits, starting BMI, metabolic health, and genetic factors. Higher starting weights typically produce greater absolute weight loss. The projections assume consistent medication use at the selected dose — dose titration periods and treatment interruptions will affect actual outcomes.