Sources & References

The calculator's weight-loss projections are derived from FDA phase 3 trial primary endpoints, and pricing data is sourced from public manufacturer and telehealth pages.

Clinical trials

• STEP-1 (Wegovy / semaglutide 2.4mg)
  14.9% mean weight loss at 68 weeks vs 2.4% placebo
  View source →
• SURMOUNT-1 (Zepbound / tirzepatide 15mg)
  22.5% mean weight loss at 72 weeks
  View source →
• OASIS-4 (oral semaglutide 25mg)
  13.6% mean weight loss at 68 weeks
  View source →
• SURPASS-2 (Mounjaro / tirzepatide for T2D)
  20.9% peak weight loss as off-label use
  View source →
• ATTAIN-1 (Foundayo / orforglipron)
  14.7% mean weight loss at 72 weeks (oral, non-peptide)
  View source →
• REDEFINE-1 (CagriSema / cagrilintide+semaglutide)
  20.4% mean weight loss at 68 weeks
  View source →
• SCALE (Saxenda / liraglutide)
  8.4% mean weight loss at 56 weeks
  View source →

Pricing references

• LillyDirect — manufacturer self-pay for Zepbound and orforglipron
• NovoCare — patient assistance for Wegovy, Ozempic, Saxenda
• GoodRx GLP-1 service
• Hims, Ro, Found, Lemonaid, LifeMD public pricing pages (April 2026 snapshot)

Modeling notes

We model weight loss as an exponential approach to plateau: pct(t) = peak × (1 - exp(-t / τ)) where τ = peakWeeks / 2.5. This produces curves that closely match published trial graphs at weeks 4, 12, 28, 52, and 68/72. The model assumes full adherence and does not account for plateaus, dose escalation, or weight regain after stopping.

Pricing snapshot: April 2026. We update periodically.