Basal Metabolic Rate
Even when your body is at rest it needs energy and burns calories to get the energy. The requirement of energy, if you rest for the whole day, is your basal metabolic rate. Energy requirement for breathing, organ functions, blood circulation, and basic neurological functions come under BMR.
Calculating BMR
Calorimetry
Calorimetry is the method of knowing changes in energy consumption of an organism. Direct calorie measurement measures the amount of heat generated by a person set in a small enclosure and indirect calorimetry measures oxygen utilization through gas analysis to calculate energy consumption.
Mathematical Formula
However accurate calorimetry is but they are expensive, difficult to get to, and involve a lot of time. To combat this situation, easily accessible and affordable techniques that may not be very accurate but give good estimate of BMR have been devised over the past century.
Our Weight loss calculator uses well established formula to prepare a daily macro consumption plan for you. Try it (for women | for men ).
Following are some of the mathematical forumula used to calculate BMR
Harris-Benedict (1909)
| For | Units | BMR Formula |
|---|---|---|
| Men | kg & cm | 66.5 + (13.75 X w ) + ( 5.003 X h ) – ( 6.755 X a ) |
| in & lb | 66 + ( 6.2 X w ) + ( 12.7 X h ) – ( 6.76 X a ) | |
| Women | kg & cm | 655 + ( 9.563 X w ) + ( 1.850 X h ) – ( 4.676 X a ) |
| in & lb | 655 + ( 4.35 X w ) + ( 4.7 X h ) - ( 4.7 X a ) |
Roza and Shizgal (1984)
| For | Units | BMR Formula |
|---|---|---|
| Men | kg & cm | 88.362 + (13.397 X w ) + ( 4.799 X h ) – ( 5.677 X a ) |
| in & lb | 88 + ( 6.1 X w ) + ( 12.2 X h ) – ( 5.7 X a ) | |
| Women | kg & cm | 447.593 + ( 9.247 X w ) + ( 3.1 X h ) – ( 4.330 X a ) |
| in & lb | 655 + ( 4.2 X w ) + ( 7.9 X h ) - ( 4.3 X a ) |
Mifflin and St Jeor (1990)
| For | Units | BMR Formula |
|---|---|---|
| Men | kg & cm | (10 X w ) + ( 6.25 X h ) – ( 5 X a ) + 5 |
| in & lb | (4.5 X w ) + ( 15.9 X h ) – ( 5 X a ) + 5 | |
| Women | kg & cm | (10 X w ) + ( 6.25 X h ) – ( 5 X a ) - 161 |
| in & lb | (4.5 X w ) + ( 15.9 X h ) – ( 5 X a ) - 161 |
Mathematical Formula are Not Perfect
Error in mathematical formula may seem small (40-60 calories) at first, but is approximately equal to 3 K.G. of weight during a year.
Also, these formulas also consider all people of the same age, height, sex, and weight to have the same BMR, which is incorrect. Effect of lean body mass on your BMR is not negligible and should always be accounted for.
One formula that is based on lean body mass, i.e. Katch McArdle and Cunningham formula, calculates your BMR using lean body mass and not body weight.
Professionals are continuously improving formula to reduce errors in such calculations.