What is BMR?
Your basal metabolic rate (BMR) is the energy your body burns at complete rest to keep you alive: breathing, blood flow, body temperature and the work of your organs. For most people it makes up 60% to 70% of all the Calories they burn in a day. The rest comes from movement, exercise and digesting food.
Example: a 25-year-old man, 5 ft 10 in and 160 lb, has a BMR of about 1,717 Calories a day with the Mifflin-St Jeor formula. A woman of the same age, height and weight has a BMR of about 1,551 Calories.
BMR formulas
- Mifflin-St Jeor: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5 for men, − 161 for women.
- Revised Harris-Benedict: men 13.397W + 4.799H − 5.677A + 88.362; women 9.247W + 3.098H − 4.330A + 447.593.
- Katch-McArdle: 370 + 21.6 × lean body mass (kg). It uses body fat instead of sex and age.
What changes your BMR
Muscle burns more energy than fat, so more muscle means a higher BMR. BMR falls slowly with age as muscle mass drops, and it is usually lower in women because of a higher share of body fat. Strength training is the most reliable way to keep it up.
Frequently asked questions
Is BMR the same as RMR?
Nearly. Resting metabolic rate (RMR) is measured under less strict conditions and is usually a little higher, but the two are often used interchangeably.
Should I eat my BMR to lose weight?
Eating below your BMR is rarely needed. Aim below your total daily calories, which is BMR times your activity level, as shown in the table.
How accurate are the formulas?
For most people they land within about 10% of a lab measurement. Very muscular or very heavy people can be further off.