GLP-1 Weight Loss Timeline & Cost Calculator
Project your expected weight loss on semaglutide (Wegovy, Ozempic) or tirzepatide (Zepbound, Mounjaro) based on starting weight, dose, and time. Includes total cost projection comparing brand-name vs compounded options.
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⚠️ Lean mass concern
Without resistance training, approximately 25-40 percent of your weight loss will be lean mass (muscle) rather than fat. Strongly consider adding 2-3 sessions of strength training per week and at least 80 grams of protein daily to mitigate this.
Methodology: The calculator uses average weight loss percentages from the STEP 1-5 trials (semaglutide) and SURMOUNT-1 to SURMOUNT-4 trials (tirzepatide). Cost figures reflect 2026 US market rates. Individual results vary substantially. See full semaglutide guide or tirzepatide guide.
How GLP-1 weight loss progresses month by month
Weight loss on GLP-1 medications follows a predictable trajectory shaped by dose titration and metabolic adaptation. Most patients reach the maintenance dose at month 4-5 and continue losing weight at a slowing pace through month 18.
Months 1-4: Titration phase
Starting dose (0.25 mg semaglutide / 2.5 mg tirzepatide) increased every 4 weeks. Average weight loss 5-8 percent of starting body weight. Side effects most pronounced after each dose increase.
Months 5-12: Active loss phase
Maintenance dose reached. Steady weight loss continues at approximately 1-1.5 lbs per week, slowing over time. Most patients reach 12-17 percent (semaglutide) or 15-22 percent (tirzepatide) by month 12.
Months 12-18: Plateau phase
Weight loss slows and most patients reach a stable plateau. This is the new "set point" the body has adapted to.
Months 18+: Maintenance phase
Ongoing weekly injection at maintenance dose. Discontinuation studies show 60-70 percent of lost weight is regained within 12-24 months of stopping.
Frequently asked questions
How accurate is this GLP-1 weight loss calculator? +
The calculator uses average weight loss percentages from the STEP 1-5 trials (semaglutide) and SURMOUNT-1 to SURMOUNT-4 trials (tirzepatide) published in the New England Journal of Medicine and JAMA. Individual results vary substantially - approximately 15 percent of patients lose less than 5 percent of body weight, while another 15-20 percent lose more than 25 percent. The calculator provides a median trajectory, not a guaranteed outcome.
How much weight will I actually lose on semaglutide? +
In the STEP 1 trial, average weight loss at 68 weeks was 14.9 percent of starting body weight on the maximum dose (2.4 mg/week). 85 percent of patients achieved at least 5 percent weight loss; 50 percent achieved at least 15 percent. Tirzepatide produces roughly 4-6 percentage points more weight loss on average.
Is compounded semaglutide cheaper than Wegovy? +
Yes. Compounded semaglutide from licensed 503A pharmacies through telehealth weight-loss clinics typically runs $199-$499 per month versus $1,300+ for brand-name Wegovy at retail. The calculator includes both options for comparison.
How long do I need to take GLP-1 medications? +
GLP-1 medications are generally considered long-term or indefinite therapy. Studies show approximately 60-70 percent of weight lost is regained within 12-24 months of discontinuation. Most patients require ongoing maintenance dosing.
What is the average total cost of GLP-1 weight loss medication over 5 years? +
At $300/month average compounded pricing, 5-year total is approximately $18,000. At brand-name Wegovy retail without insurance ($1,300/month), 5-year total is approximately $78,000. With insurance coverage and prior authorization, out-of-pocket can drop to $1,500-$6,000 over 5 years.