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Basal Metabolic
Rate
What Is Your BMR?
• Your BMR measures the minimum calorie
requirement your body needs to stay alive in
a resting state
• It is the amount of calories your body would
need if you were to stay in bed all day
How Many Calories Is This?
• About 65% of your calorie intake is
responsible for just supplying your BMR
• You need calories to:
– Pump your heart
– Breathe
– Control your body temperature
– And many other things
Do We All Have The Same BMR?
• We all have different BMR and there are
many things that will affect what that rate is
• Your BMR is the largest factor in
determining your overall metabolic rate
(how your body burns calories)
• BMR ranges about 65 – 70 Calories per Hour
in an average 70 kg man.
How To Calculate BMR
Women:
655 + (4.35 x weight in pounds) + (4.7 x height in inches) - (4.7 x age in years)
Men:
66 + (6.23 x weight in pounds) + (12.7 x height in inches) - (6.8 x age in years)
Whereby:- 1 kg = 2 lb
1 m = 39.36 inches
Factors that influence BMR
Genetics
• Some people are born with slower
metabolisms than others
• Some people are born with faster
metabolisms than others
Gender
• Men have a greater muscle mass and a lower
body fat percentage (10-15% higher BMR
than womem)
• The higher your muscle mass, the higher
your metabolism
• Male sex hormone
Age
• Your BMR will reduce as you age. Due to
reduced muscle size and increase in adipose
tissue
• After 20 years of age, your BMR drops about
2% every year
Weight
• The more you weigh, the higher your BMR
• The BMR of an obese woman is 25% higher
than a woman of an appropriate weight
Body Surface Area
• The greater your body surface area, the
higher your BMR
• Tall, thin people have higher BMRs
Body Fat Percentage
• The lower your body fat percentage, the
higher your BMR
Diet-Malnutrition
• If you reduce your calorie intake suddenly,
your BMR can drop by 30%
• Your body wants to ensure that it is always
has the calories it needs to survive, so
cutting calories quickly will switch your body
into a “survival” mode
Body Temperature
• For every 1 degree increase in your body
temperature, your BMR increases by
approximately 14%
• Chemical reactions occur faster in your body
at higher temperatures
• You burn a lot more calories while you are
sick or have fever
External Temperature
• Exposure to cold temperatures will increase
your BMR
• Prolonged exposure to heat will also
increase your BMR
Glands
• Your thyroid gland (butterfly-shaped gland
in your neck) is responsible for making
thyroxin
• The more thyroxin produced, the higher
your BMR
• Thyroxin increases the rates of chemical
reactions in the cells.
Glands
• Growth hormone increases about 15% of
BMR
• This is due to direct stimulation of cellular
metabolism
Exercise
• Exercise helps to build lean muscle tissue
• The more lean muscle tissue, the higher your
BMR
• This means you will burn more calories –
even when you are sleeping!