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Basal Metabolic Rate (BMR)

Every human body is losing energy every day even without any physical activities – when at rest in comfortable environment, not eating, not digesting and not stressing. The amount of energy our body spending when it is at rest called Basal Metabolic Rate (BMR) – the measurement of energy spent by existing functioning body organs, the energy is needed for body to maintain life, the minimum amount of energy needed to keep body functioning, including breathing and keeping heart beating. Actually the BMR is the energy we use every day to keep us alive and healthy including vital functions such as breathing and keeping warm. In general, human body spend about 10% energy for digestion; 20% for additional activities (work, sport, mental activities, stress, etc.) and about 70% complicated body functioning (BMR).

BMR is important indicator in cases if you need to control your weight – to loose or gain kilograms. You should know how much energy you need for your body life maintenance and how much additional calories you need to loose or gain for having targeted weight. Consuming more kilo-calories per day than your BMR will help you gain weight, and consuming less kilo-calories than your BMR requires, can cause you to lose additional weight. Special attention should be paid to physical activities (sport, cardio, walking, dancing, etc.) because different daily activities burn calories.

It is interesting to know that different body organs spend energy in following way:

Organs Functions Energy consumption
Liver Processing and storing energy, fighting infections, clearing blood of drugs/toxins 27%
Brain Controlling thought, memory, motor actions, senses, every action that regulates the body 19%
Heart Pumping oxygen-rich blood to all cells 7%
Kidneys Filtering system 10%
Skeletal muscle Moving the body 18%
Other organs Performing all other internal functions 19%

Based on estimates by M. Elia in Organ and Tissue Contribution to Metabolic Weight (Raven Press, 1992).

Basal Metabolic Rate – calculation

Basal Metabolic Rate

Basal Metabolic Rate

Basal Metabolic Rate (baseline calories) is the number of calories required by body for supporting vital body functions. While muscle mass burns more than fat mass, body organs use up most of the calories for breathing, heart beating, circulating blood, regulating body temperature, growing new cells, food chewing, swallowing and digestion, blinking, fighting stress, supporting brain and nerve activity, etc.

The BMR formula uses your height, weight, age and gender to calculate your Basal Metabolic Rate. Knowing your personal Basal Metabolic Rate, you can easily create and calculate smart strategy for weight loss or weight maintenance.

Calculation/estimation of your BMR is possible using the Mifflin-St. Jeor equation, a formula introduced in 1990. The Mifflin-St. Jeor equation is now considered the standard when it comes to calculating BMR.

Basal Metabolic Rate – English BMR Formula

For women: BMR = 655 + ( 4.35 x weight in pounds ) + ( 4.7 x height in inches ) – ( 4.7 x age in years )

For men: BMR = 66 + ( 6.23 x weight in pounds ) + ( 12.7 x height in inches ) – ( 6.8 x age in year )

Basal Metabolic Rate – Metric BMR Formula

For women: BMR = 655 + ( 9.6 x weight in kilos ) + ( 1.8 x height in cm ) – ( 4.7 x age in years )

For men: BMR = 66 + ( 13.7 x weight in kilos ) + ( 5 x height in cm ) – ( 6.8 x age in years )

BMR

BMR

Weight and height are very important components of the BMR because more mass (weight) you have, the more energy (fuel) you need to sustain larger body organs. This is why heavier and taller persons have higher Basal Metabolic Rate. At the same time, you need to know that if you lose weight, your BMR will decrease. In addition, when you practice sport regularly and gain dense, heavier muscle mass, your BMR will increase.

Another important component of BMR is your age. It is well known that metabolic rate decreases as you age – muscle mass declines by 5-10% each decade after 30.

You would ask why gender is important for BMR? The answer is simple – because body composition (muscles/bones/fat) is different in men and women. In general, Basal Metabolic Rate in women is smaller by 5-10% comparing with men of similar age group.

For making clever decisions and properly calculating total calories you need to consume daily for losing weight or gaining kilograms or maintaining your ideal weight, you need to add additional calculations depending on your daily activities. For calculating your Total Daily Calorie Needs, you should multiply your BMR by the appropriate activity factor, as follows:

Daily activities Activity factor
Sedentary
Light or no exercise and desk job BMR x 1.2
Light exercise or sports 1-3 days a week BMR x 1.375
Moderate exercise or sports 3-5 days a week BMR x 1.55
Hard exercise or sports 6-7 days a week BMR x 1.725
Hard daily exercise or sports and physical job BMR x 1.9

Health experts for most accurate BMR calculations take measurements of carbon dioxide and oxygen analysis after a subject has fasted for 12 hours and has had eight hours of sleep.

In all cases if you are planning to calculate your personal BMR and develop weight control strategy, don’t forget to check your Body Mass Index (BMI) and identify your ideal normal weight.


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