What Is BMR?
Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic life-sustaining functions at complete rest — breathing, circulation, cell production, and nutrient processing. BMR accounts for about 60-75% of your total daily calorie expenditure.
BMR Formulas
Mifflin-St Jeor Equation (1990) — considered the most accurate:
Male: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
Female: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
Revised Harris-Benedict Equation (1984):
Male: BMR = 88.362 + (13.397 × weight in kg) + (4.799 × height in cm) − (5.677 × age)
Female: BMR = 447.593 + (9.247 × weight in kg) + (3.098 × height in cm) − (4.330 × age)
Katch-McArdle Equation (requires body fat percentage):
BMR = 370 + (21.6 × lean body mass in kg)
Factors That Affect BMR
- Age: BMR decreases about 1-2% per decade after age 20
- Gender: Males typically have higher BMR due to more muscle mass
- Muscle mass: More muscle = higher BMR (muscle burns more calories than fat)
- Body size: Larger bodies require more energy for basic functions
- Genetics: Some people naturally have faster or slower metabolisms
- Hormones: Thyroid hormones significantly influence metabolic rate
BMR vs. RMR vs. TDEE
- BMR: Calories burned at absolute rest (measured in clinical settings)
- RMR: Resting Metabolic Rate — similar to BMR but less restrictive conditions. Usually 10-20% higher.
- TDEE: Total Daily Energy Expenditure — BMR × activity multiplier. This is your actual daily calorie burn.
Frequently Asked Questions
Which formula should I use? The Mifflin-St Jeor equation is recommended by the American Dietetic Association as the most accurate for most people. Use Katch-McArdle if you know your body fat percentage.
Can I increase my BMR? Yes — building muscle through strength training is the most effective way. Each pound of muscle burns about 6 calories per day at rest, compared to 2 calories per pound of fat.
Why is my BMR important? Knowing your BMR helps you determine how many calories you need daily. Eating below your BMR for extended periods can slow your metabolism and is generally not recommended.