What is basal metabolic rate (BMR)?
So, what is your basal metabolic rate (BMR), and why should care what your BMR is?
Your basal metabolic rate (BMR) is the amount of energy your body needs per day to maintain its current weight. Your BMR is dependent your height, weight, age, sex and level of daily activity.
Your BMR can be calculated in one of two ways. One equation is from Harris and Benedict (1) in 1918, and the other is from Mifflin et al. in 1990 (2). The Mifflin et al. equation is now viewed as the most accurate method.
Knowing your BMR is useful when dieting as it allows you to calculate the number of calories your body is using so you can adjust your calorie intake (or increase your level of exercise) as part of your weight control.
If you wish to work out your BMR then cal.culate.it offers a range of BMR calculators and these can bee seen on our ‘health and fitness’ page. The calculators work in kilograms, pounds, stone and pounds for weight, and feet and inches, or meters, for height.
Harris and Benedict Equation:-
655 + (9.6 x w) + (1.8 x h) – (4.7 x y)
Men BMR =
66 + ( 13.7 x w) + (5 x h) – (6.8 x y)
Where:
| w | = | Weight in kilograms |
| h | = | Height in CENTIMETERS |
| y | = | Age in years |
Mifflin et al. equation:-
(9.99 x w) + (6.25 x h) – (4.92 x y) + s
Where:
| w | = | Weight in kilograms |
| h | = | Height in CENTIMETERS |
| y | = | Age in years |
| s | = |
For males, +5 For women, -161 |
The values returned for BMR are kcal per day. That is, the number of kcal required to maintain your current weight.
1 kcal is equivalent to 1 Cal (dietary Calorie).
Activity
The BMR value can be adjusted for your lifestyle by multiplying by the following activity factors:
| Activity Factor | Category | Definition |
|---|---|---|
| 1.2 | Sedentary | Little or no exercise and desk job |
| 1.375 | Lightly Active | Light exercise or sports 1-3 days a week |
| 1.55 | Moderately Active | Moderate exercise or sports 3-5 days a week |
| 1.725 | Very Active | Hard exercise or sports 6-7 days a week4 |
| 1.9 | Extremely Active | Hard daily exercise or sports and physical job |
References
Harris,J.A. and Benedict,F.G. (1918) A Biometric Study of Human Basal Metabolism. Proc Natl Acad Sci U S A., Vol 4:370-3
Mifflin,M.D., St Jeor,S.T., Hill,L.A., Scott,B.J., Daugherty,S.A. and Koh,Y.O. (1990) A new predictive equation for resting energy expenditure in healthy individuals American Journal of Clinical Nutrition, Vol 51:241-247
