Basal Metabolic Rate (BMR) is the number of calories the body burns at complete rest to maintain vital functions — breathing, circulation, cell production and temperature regulation. It typically accounts for 60-70% of total daily energy expenditure. BMR is estimated using formulas like Mifflin-St Jeor (the most accurate for most people), based on weight, height, age and sex. Total Daily Energy Expenditure (TDEE) is BMR multiplied by an activity factor. Knowing BMR is the starting point for calorie planning, whether for fat loss, maintenance or muscle gain. Muscle mass is the most significant modifiable factor raising BMR.
Key points
- Calories burned at complete rest
- 60-70% of total daily energy use
- Estimated via Mifflin-St Jeor formula
- Muscle mass raises BMR