Metabolism and Metabolic Rate

Metabolism and Metabolic Rate

complex issue

Do you know what your metabolism is? Many people think it’s just to do with weight gain or weight loss, but it is far more complex than that. The dictionary meaning is,


“Your metabolism is the way that chemical processes in your body cause food to be used in an efficient way, for example to make new cells and to give you energy.” – Collins Dictionary

What many people don’t realize is that the
body burns calories even when it is resting. The body doesn’t just burn
calories when performing rigorous physical training. Our body requires calories
to produce energy for many body processes.


Your body constantly needs energy just to stay
alive. The problem is, many people take in more calories than their body needs
for fuel or energy, which raises a very good question.


How do you know how much energy your body
needs every day for good health? This is vital for weight management, as
ingested calories which are excess to energy requirements will very likely be
stored as body fat.


Metabolic Rate (BMR)


BMR or Basal Metabolic Rate refers to the
amount of energy needed by the body while it is at a resting state. When the
body is at rest, it is still burning energy, as it performs the vital processes
to keep us alive, such as breathing, the heart keeping beating, brain function,
and more.


For most people, the Basal Metabolic Rate, or
the calories that the body needs for automatic functioning, is what comprises
the largest amount – more than 60% – of total energy that the body burns every
single day.




The BMR is measured during the post-absorptive
state, which means the digestive system is at rest. Therefore, if you want to
determine your BMR, your body has to undergo at least 12 hours of fasting prior
to testing.



Most experts use a formula called the
Mifflin-St. Jeor equation to determine an individual’s BMR. However, others
prefer to use the Harris-Benedict equation, although the first is considered
more accurate than the latter. It is for this reason that the Mifflin-St. Jeor
is now deemed to be the standard BMR calculator.


Formula for
Calculating BMR


If you’re interested in calculating your BMR,
here are the 2 different types of formulas for making the calculations.


For Men


The Mifflin St. Jeor Equation

BMR = 10 x weight (kg) + 6.25 x height (cm) –
5 x age (years) + 5


The Harris Benedict Equation

BMR = (13.75 x Weight in kg) + (5 x Height in
cm) – (6.76 x Age) + 66

For Women


The Mifflin St. Jeor Equation

BMR = 10 x weight (kg) + 6.25 x height (cm) –
5 x age (years) – 161


The Harris Benedict Equation

BMR = (9.56 x Weight in kg) + (1.85 x Height
in cm) – (4.68 x Age) + 655


Factors to
Consider in Calculating Your BMR




An individual’s metabolic rate may tend to
decrease with age. It is because as we age our muscle mass declines, as much as
5-10% every ten years starting at age 30. However, this decline in muscle mass
can be prevented or at least reduced through strength training.




Gender is another important factor, as men and
women differ in ratios of muscle, fat and bone mass.  Studies reveal that a man’s BMR is higher
than a woman’s, as much as 12%. Research also shows that the BMR of a woman
changes before and after her menstrual cycle.


Weight and


The heavier you are, the more energy your body
needs in order to fuel itself at a maintenance level. If you lose weight, your
Basal Metabolic Rate will reduce as your body requirements will become less.




An increase in body temperature causes an
increase in Basal Metabolic Rate. This means that if a patient has a fever,
their BMR is also higher.




Stress causes the body to produce higher
amounts of norepinephrine and epinephrine hormones which results in a faster
heart rate and increased respiratory rate. In turn, the body experiences an
increased metabolic rate to compensate for changes in bodily functions.




Studies have also shown that consuming 5 to
100 milligrams of coffee on a daily basis may cause an increase in basal
metabolic rate, up to 7%. The same thing is also true for those who smoke.


Every person has a huge potential control over
their energy or calorie usage. While you may not be able to control how many
calories your body needs to keep your blood circulating or your heart beating,
you can certainly burn excess calories just by exercising and eating healthy


Making little changes to your daily activities
can influence your body’s metabolic rate, which will help use more energy even
while resting. 

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Rod Stone
Publisher and Supplier of Healthy Living information and products to improve
your life.

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