Temperature and Metabolism
My question has to deal with body temperature and fat
burning. The human body works to maintain a homeostatic temperature,
usually about 98.6 degrees F. Fuel is burned in the body to generate
heat through metabolism to sustain this. One of those sources of fuel is
fat stored in our body. Can there be any significant fat loss in the
body if the body temperature is lowered by external conditions, thus
forcing the increase in metabolism? I see that many swimmers seem to be
very low in body fat percentage. They may spend much time devoted to
swimming in water with a temperature that is quite a bit lower than that
of the human body. I understand that there are other factors involved in
swimming that would cause fat burning besides just temperature. If a
person were to drink cold water throughout the day during sedentary
periods and assuming this cold water was able to decrease body
temperature, would he or she find any significant results in fat burning?
I'm curious as to your take on this subject.
Well, you'd have to drink a darn lot of water to make a dent. 1 Calorie =
energy to raise 1 kg of water 1 degree celsius. Let's say you drink ice
water = 0 C, raised to your body temperature, = 35 C or so. If you drink a
gallon a day, 4 liters, that's only 140 Calories. That's a lot of
water. Plus you put stress on your body drinking that much, as it has to
fight to keep from losing ions. Plus you'll be going to the bathroom all
the time. Maybe if you combine that with having only one bathroom on the
top story of a 10 story building with no elevator, you'd see a big effect.
The physique of swimmers has far more to do with their exertion levels than
with water temperature, otherwise you'd expect them to be leaner than
runners or rowers or cyclists etc, which just isn't the case. Swimmers may
have a slight advantage in that even in hot weather they won't suffer much
thermal discomfort at high levels of exertion, but beyond that I don't see
water heat conduction playing a large part.
Donald Yee Ph.D.
San Francisco Estuary Institute
180 Richmond Field Station,
1325 South 46th St. Richmond, CA 94804
I don't think cold water can decrease body temperature. By the time it
reaches the body it has been through the entire digestive system and is
warmed to body temperature. Even in swimmers in cool water the body
temperature shouldn't drop significantly. The capillaries in the skin will
vasocontrict to keep the core of the body the same temperature. While its
true that to KEEP that temperature at 98.6 the body probably will burn more
calories, just as your furnace does in the winter, the only way that fat will
be burned is if the carbohydrate stores are depleted first. Glucose is the
body's preferred energy source and it will use that until it runs out. Then
it starts converting other food sources INTO glucose. Fat can be turned into
glucose a little at a time until there is no need for it anymore.
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Update: June 2012