Estimate your maintenance calories using the Mifflin–St Jeor equation, then overlay the weight-loss trajectory you’d expect on a GLP-1 protocol. Curves are fit to the published Phase-3 means — yours will vary.
Inputs
Mifflin–St Jeor uses separate constants for each.
Basal metabolic rate
Daily maintenance calories
Moderately active
1 kg of fat ≈ 7,700 kcal
Population-mean curve from clinical trials — not individualized
−7.2%
−18.5%
−20.6%
Source — SURMOUNT-1 (Jastreboff et al., NEJM 2022) — 20.9% at 72 weeks. Individual response varies widely; trial placebo arms lost ~2–5% over the same window.
BMR — basal metabolic rate — is how many calories your body burns at rest, just to keep organs running. The Mifflin–St Jeor equation (1990) is the current gold standard for predicting BMR from weight, height, age, and sex:
male: 10·kg + 6.25·cm − 5·age + 5
female: 10·kg + 6.25·cm − 5·age − 161
Total daily energy expenditure (TDEE) multiplies BMR by an activity factor between 1.2 (sedentary) and 1.9 (physical job). The factors come from Harris-Benedict-era research and remain a reasonable back-of-the-envelope for adults.
Calorie deficit targets assume ~7,700 kcal per kilogram of fat mass. This is a population-mean figure — real loss rates are slower once adaptive thermogenesis kicks in (typically after 6–10 weeks of deficit).
GLP-1 receptor agonists don’t cause weight loss purely by creating a calorie deficit — they change gastric emptying, appetite, and resting energy expenditure. A simple deficit model under-predicts early loss and over-predicts the plateau, so we use an exponential-to-plateau shape that tracks the real Phase-3 curves far better:
W(t) = W₀ − ΔW_max · (1 − e−t/τ)
Parameters are fit to the published trial means:
These are population means. Trial participants ranged from non-responders (under 5% loss) to high responders (over 30%). Titration schedule, adherence, and BMI at baseline all modify the curve. The projection is a rough benchmark, not a forecast.