How Our GLP-1 Weight Loss Calculator Works
Our GLP-1 calculator uses a compounding weight loss model derived from two landmark clinical trials: STEP-1 (semaglutide 2.4mg, 68 weeks) and SURMOUNT-1 (tirzepatide 5-15mg, 72 weeks). The model applies weekly weight loss rates calibrated to match the average outcomes reported in these peer-reviewed studies published in the New England Journal of Medicine.
The calculator accounts for the non-linear nature of GLP-1 weight loss — rapid initial loss during the first 6 months that gradually plateaus as the body reaches a new equilibrium. This mirrors the real-world experience: most patients see the fastest results between months 2-6 after completing the titration (dose-increase) phase.
Ozempic Weight Loss by Starting Weight
Your starting weight significantly affects total pounds lost, even though percentage-based loss is relatively consistent. Here's what the STEP-1 data suggests for semaglutide at different starting weights over 12 months:
| Starting Weight | Expected Loss (12 mo) | Projected Final Weight |
|---|---|---|
| 160 lbs | 20-28 lbs (12-17%) | 132-140 lbs |
| 180 lbs | 23-31 lbs (13-17%) | 149-157 lbs |
| 200 lbs | 26-34 lbs (13-17%) | 166-174 lbs |
| 220 lbs | 29-37 lbs (13-17%) | 183-191 lbs |
| 250 lbs | 33-43 lbs (13-17%) | 207-217 lbs |
| 280 lbs | 36-48 lbs (13-17%) | 232-244 lbs |
| 300 lbs | 39-51 lbs (13-17%) | 249-261 lbs |
Mounjaro Dosing Schedule and Expected Results
Tirzepatide (Mounjaro/Zepbound) follows a dose-escalation schedule, with weight loss increasing at higher doses. Here's the SURMOUNT-1 data by dose level over 72 weeks:
| Dose | Avg Weight Loss (%) | Avg Loss for 230 lb Person | Titration Schedule |
|---|---|---|---|
| 5 mg | 15.0% | 34.5 lbs | Start at 2.5mg, increase at week 4 |
| 10 mg | 19.5% | 44.9 lbs | Titrate through 5mg first |
| 15 mg | 20.9% | 48.1 lbs | Titrate through 5mg → 10mg |
Tips to Maximize Your GLP-1 Weight Loss
While GLP-1 medications are effective on their own, combining them with lifestyle changes can significantly improve your results:
Prioritize Protein
Aim for 0.7-1g of protein per pound of body weight daily. GLP-1 medications can cause lean mass loss — adequate protein helps preserve muscle during weight loss.
Resistance Training
Strength training 2-3 times per week helps maintain and build muscle. Studies show patients who exercise while on GLP-1s lose more fat and less muscle.
Stay Hydrated
Drink at least 64 oz of water daily. GLP-1 medications slow gastric emptying, and dehydration can worsen nausea and constipation side effects.
Track Progress
Take weekly photos and measurements, not just scale weight. Body recomposition can occur where you lose fat but gain muscle, making the scale misleading.
Frequently Asked Questions
How accurate is the GLP-1 weight loss calculator?
Our calculator uses average weight loss rates from the STEP-1 (semaglutide) and SURMOUNT-1 (tirzepatide) clinical trials. These represent population averages — individual results vary based on starting weight, dosage, diet, exercise, and biological factors. The calculator provides a reasonable estimate, not a guarantee.
How much weight will I lose on Ozempic in 6 months?
Based on STEP-1 clinical data, the average patient loses 8-15% of their starting body weight in 6 months on semaglutide (Ozempic/Wegovy). For a 200 lb person, that's approximately 16-30 lbs. Results accelerate after the titration phase (first 2-3 months) when the full therapeutic dose is reached.
Is Mounjaro better than Ozempic for weight loss?
Clinical trials show tirzepatide (Mounjaro/Zepbound) produces greater average weight loss than semaglutide (Ozempic/Wegovy). SURMOUNT-1 showed 20.9% weight loss at the highest dose (15mg) vs 14.9% in STEP-1. Tirzepatide is a dual GIP/GLP-1 agonist, which may explain the enhanced results.
What is the maximum weight loss on Ozempic?
In the STEP-1 clinical trial, the top 25% of responders lost more than 20% of their body weight on semaglutide 2.4mg. Some individuals lost over 30%. Factors that maximize results include consistent dosing, high-protein diet, regular exercise, and adequate sleep.
How long should I stay on GLP-1 medication?
Most patients reach maximum weight loss between 12-18 months on GLP-1 medications. Weight loss typically plateaus around 60-72 weeks. Many patients continue medication long-term to maintain results, as studies show significant weight regain (up to 2/3 of lost weight) within 1 year of stopping.
Will I regain weight after stopping Ozempic?
Research shows most patients regain a significant portion of lost weight after stopping GLP-1 medications. A STEP-1 extension study found patients regained about 2/3 of their lost weight within 1 year of discontinuation. This is why lifestyle changes during treatment — diet, exercise, and behavioral habits — are critical for long-term success.
Related Resources
Medical Disclaimer: This calculator provides estimates based on average results from clinical trials (STEP-1 and SURMOUNT-1). Individual results vary significantly based on dosage, lifestyle, adherence, and biological factors. This tool is for informational purposes only and does not constitute medical advice. Always consult a healthcare professional before starting any medication.