What is Basal Metabolic Rate (BMR)?
Basal Metabolic Rate (BMR) is the amount of total energy expenditure necessary to maintain our basic bodies function under basal condition.
Basal condition means-
Person should be at rest.
Person should be awake.
Person should be without food for about 12 hours.
Person should be in a comfortable temperature (200-250C).
Importance of Basal Metabolic Rate:
Total daily calories requirement in our body = Basal Metabolic Rate + calories required for physical activity + calories required for food digestion.
So, Basal Metabolic Rate (BMR) is important to calculate the daily calorie requirement of a person and planning of diets.
The most useful way of measuring the total daily calories requirement is as a multiple of Basal Metabolic Rate (BMR). Sedentary workers use only 1.1 – 1.2 × BMR. By contrast, heavy workers may use 6 – 8 × BMR.
Calculation of BMR by Basal Metabolic Rate Formula:
Basal metabolic rate in male
= 66 + (6.23× weight in pound) + (12.7 × height in inches) – (6.8 × age in years).
= 66 + (13.7 × weight in kilogram) + (5 × height in cm) – (6.8 × age in years).
Basal metabolic rate in female
= 655 + (4.35× weight in pound) + (4.7 × height in inches) – (4.7 × age in years).
= 655 + (9.6× weight in kilogram) + (1.8 × height in cm) – (4.7 × age in years).
Average normal value of BMR is
In Male: 35-38 Kcal/m2 of body surface area/hour.
In Female: 32-35 Kcal/m2 of body surface area/hour.
Factors speed up the Basal Metabolic Rate:
Young age – BMR is high in young age because of young person contains more muscle tissue which is metabolically more active.
Male sex – BMR is high in male because of male’s bodies contain proportionally more muscle tissue.
More body surface area – BMR is high in person with more body surface area.
High or low environmental temperature – When the environmental temperature is higher than body temperature, BMR accelerated, and the metabolic rate increases about 14% for the elevation of each degree Celsius. When the environmental temperature is lower than body temperature, metabolic rate is increases through heat producing mechanisms such as shivering.
Pregnancy – BMR increase in pregnancy.
Emotional state – BMR increase in emotion.
Hormones – Thyroid hormone, testosterone, growth hormone, and catecholamine increases BMR.
Factors slow down the Basal Metabolic Rate:
Older age – BMR decrease in older age because of muscle tissue is replaced by fatty tissue in older age, which is metabolically less active.
Female sex – BMR is low in female because of female’s bodies contain proportionally more fatty tissue.
Less body surface area – BMR is low in person with less body surface area.
Starvation – metabolism will slow down in starvation for surviving the life.