Ask A Scientist© Zoology Archive

name       p
status     educator
age        30s

Question - IS IT TRUE THAT IF YOUR BODY TEMP IS
NORMALLY LOW AT ALL TIMES, THAT YOUR METABOLISM IS SLOWER?


There is a rule of thumb in chemistry/biology that states that for every ten
degrees centigrade rise in temp the reaction rate doubles. To what extent
this holds true for an entire organism is uncertain since there are a number
of physiological mechanisms which are at play. If we take the position that
even a ½ degree C difference lowers metabolism in humans knowing that women
generally have a slightly lower core temp than men implies women have a
lower metabolic rate than men. The energy systems of the body are about 20%
efficient with the rest released as heat. Any factor which changes the
energy released from food affects a person's metabolic rate. With these and
other approaches in mind biologists have found that all of the following
affect metabolic rate...which is defined as the amount of food energy
converted per unit of time.

Exercise
Ingestion of food
Age
Shivering
Body size
Gender
Climate
Body Temperature
Hormones

And probably some other things that slip my slowly metabolizing mind.

There is another term called Basal Metabolic rate which has come out of all
the resaerch on what affects metabolic rate and allows for comaparisons
among people. This measures the total amount of energy consumed by the body
per unit time. The BMR is measure by human calorimeters which is an
insulated chamber in which the person is placed and measures how much heat
they release...studies with this system have shown that the things I listed
above do affect BMR. For instance a person who is adapted to living in the
cold will have a 15-25% increase in their BMR. Much of this has to do with
physiological/hormonal (thyroud hormone being one of the more important)
changes that shift heat production in the body.


Peter Faletra
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