BMR

Basal Metabolic Rate

The basal metabolic rate (BMR) is the amount of energy needed to body when the body is at complete mental and physical rest, i.e. in a room with comfortable temperature and humidity, awake and sitting in a reclining position and the digestive system is inactive. It is essentially the minimum energy required to maintain the heart rate, respiration, kidney function and all other body functions.

There are three equations used to calculate BMR by calculator, which are as follows:

1. Mifflin - St. Jeor equation

(For men)
BMR = 10W + 6.25H - 5A + 5

(For women)
BMR = 10W + 6.25H - 5A - 161

2. Katch - McArdle formula

BMR = 370 + 21.6(1 - F)W

3. Revised Harris -Benedict equation

(For men)

BMR = 13.397W + 4.799H - 5.677A + 88.362

(For women)

BMR = 9.247W + 3.098H - 4.330A + 447.593

Note:
W = body weight in kg
H = body height in cm
A = Age
F = body fat in percentage

Normal BMR value
Men = 1600 kcal/day
Women = 1400 kcal/day

There are many factors that affect the BMR, these are as follows:
-Genetic
-Gender
-Glands
-Exercise
-Pregnancy
-External temperature
-Body temperature/health
-Diet
-Body fat percentage
-Body surface area
-Weight
-Age

BMR has following significance:

1. The determination of BMR is the principal guide for diagnosis and treatment of thyroid disorders.

2. BMR is above normal rate in fever, diabetes insipidus, leukemia & polycythemia.

3. The BMR is low in starvation, under nutrition, hypothalamic disorders, Addison's disease.

4. BMR aids to known the total amount of food or calories required to maintain body weight.

5. If BMR is less than 10% of the normal, it indicates moderate hypothyroidism. In major hypothyroidism, the BMR may be decreased to 40% to 50% below normal.