Basal Metabolic Rate (BMR) is the minimum number of calories your body needs to sustain vital functions like breathing, circulation, and cell production while completely at rest.
How BMR Is Calculated
The Mifflin-St Jeor equation (most accurate):
- Men: BMR = (10 × weight kg) + (6.25 × height cm) - (5 × age) + 5
- Women: BMR = (10 × weight kg) + (6.25 × height cm) - (5 × age) - 161
BMR vs. TDEE
BMR accounts for about 60–70% of total daily energy expenditure (TDEE). TDEE adds your physical activity and thermic effect of food on top of BMR.
Why BMR Matters for Weight Management
Because BMR represents the majority of daily calorie burn, crash diets that drop calories too low can trigger "metabolic adaptation" — the body lowers its BMR to conserve energy, making further weight loss harder and rebound weight gain more likely. This is a key reason moderate, sustainable deficits tend to outperform extreme ones long-term.
Harris-Benedict vs. Mifflin-St Jeor
The older Harris-Benedict equation (1919, revised 1984) tends to overestimate BMR by 5–15% compared to indirect calorimetry. The Mifflin-St Jeor equation (1990), used above, has been shown in validation studies to be more accurate for most adults and is now the equation recommended by the Academy of Nutrition and Dietetics.