Estimating BMR — Mifflin-St Jeor and Harris-Benedict
Sources and review status
Review pending — this text hasn’t been signed off by a reviewer yet.
Health-sensitive topic: not used for AI answers until reviewed.
See this lesson’s sources0% read · 2 min left
Basal metabolic rate is the energy your body burns at rest; the Mifflin-St Jeor equation is the most accurate common estimate.
Detail
Basal metabolic rate (BMR) is the energy expended at complete rest to sustain life (breathing, circulation, cell maintenance). It is the largest component of daily energy use, typically 60–70% of total expenditure. Resting metabolic rate (RMR) is a slightly less strict measurement but is often used interchangeably. BMR is estimated from sex, weight, height, and age using prediction equations:
Mifflin-St Jeor (1990) — the recommended default, validated as the most accurate for modern populations (within ~10% of measured for most people):
- Men: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age yr) + 5
- Women: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age yr) − 161
Harris-Benedict (1919, revised 1984) — older and tends to overestimate by ~5–15% in sedentary people:
- Men: BMR = 88.362 + (13.397 × weight kg) + (4.799 × height cm) − (5.677 × age yr)
- Women: BMR = 447.593 + (9.247 × weight kg) + (3.098 × height cm) − (4.330 × age yr)
These are estimates, not measurements — individual metabolism varies with lean mass, genetics, and history (equations using lean body mass, e.g. Katch-McArdle, can be more accurate for lean, muscular people). BMR is the starting point; multiply by an activity factor to get total daily energy expenditure (see Total Daily Energy Expenditure (TDEE) and Activity Factors for Estimating TDEE).
Key facts
- BMR = resting energy to stay alive; ~60–70% of daily expenditure.
- Mifflin-St Jeor (recommended): M = 10W + 6.25H − 5A + 5; W = 10W + 6.25H − 5A − 161 (kg, cm, yr).
- Harris-Benedict (older): overestimates ~5–15% in sedentary people.
- Equations are estimates; lean-mass formulas (Katch-McArdle) suit muscular individuals.
- BMR × activity factor = TDEE.
Connections
- Total Daily Energy Expenditure (TDEE) — scaling BMR to total daily expenditure.
- Activity Factors for Estimating TDEE — the multipliers applied to BMR.
- Setting Calorie Targets for Fat Loss, Maintenance, and Gain — turning TDEE into goal-based calorie targets.
- Factors Affecting Caloric Intake — what drives individual calorie needs.
Sources
See how this applies in practice, with honest limits on what the plan changes.
Educational content only — not medical advice. Always consult a qualified professional for individualized guidance, especially around injury, pregnancy, or medical conditions.