Everyone knows you need 8 glasses of water each day to stay
healthy right? Wrong! Of course, drinking water is essential and
the best way to get the water you need is by drinking water (not soda, juice,
or sports drinks), but it is a misconception that you need to drink 8 glasses
per day and that more is always better.
The National Academy of Sciences recently concluded that
most Americans are adequately hydrated.
Direct Quote “The vast majority of healthy people adequately meet their
daily hydration needs by letting thirst be their guide.”
Typically, about 80% of your total water intake comes from
water and other beverages with about 20% from the food you eat.
Another associated myth is that if you wait until you are
thirsty it is too late because you are already dehydrated. For the vast majority of people your
physiological thirst mechanism is triggered before you become dehydrated.
Another myth is that if your urine is yellow or deep yellow
you are dehydrated. This could
indicate dehydration but urine color is also strongly affected by other factors
including intake of certain vitamins and other chemicals we take in from food
and drinks.
Dangers of too much
water intake
There is a very real danger from excessive water intake and
the number of people affected by this is growing – particularly in sports. This may all stem from a paper published by
the US Military stating that soldier should drink 64 ounces of water per hour
in order to improve performance. It was
and still is widely embraced although there is not scientific support for this
advice. Even the American College of Sports Medicine recommends
“…drinking ahead of thirst.” The
problem is this can be taken too far and in fact excess water impairs
performance and actually can kill someone if it is excessive enough. It is important to note that data
demonstrates mild degrees of dehydration do not impair performance.
Excessive water intake coupled with exercise can result in
exercise-associated hyponatremia (EAH).
EAH is also commonly referred to as “Water Intoxication.” In EAH, the body’s cells, including those in
the brain, swell with too much water, which can be fatal. When the body has too much water relative
to its salt level, the salt level in the blood drops too low which leads to
significant problems.
The Right Strategy
for Water Intake
The easy answer to proper hydration is to pay attention to
your thirst and drink accordingly.
This applies to sports drinks as well. Also it goes without saying that not
getting enough water is not advisable.
When you do not drink enough water it puts you at a much higher risk for
kidney stones and this is one of the most painful conditions there is! Dehydration can also negatively
impact cognitive function and mood.
Dehydration is more common in children and the elderly, and
risks of dehydration get higher as the temperature and humidity rise. During hot humid weather the body sweats
profusely but because of the humidity sweat does not evaporate so cooling is
not nearly as effective and the body just keeps sweating without much effect on
body temperature. Dehydration is also
much more common in extremely cold temperatures below freezing because the air
becomes extremely dry and with each breath moisture is lost. In addition, in cold temperature the thirst
mechanism can fail to kick in. The
end result is that dehydration is a very serious risk in prolonged exposure and
exercise in cold environments!
So How Much Water Do
You Need?
While you probably do not need 8 glasses of water per day –
it probably is not going to hurt you in most cases. Actual fluid intake and needs will vary
from individual to individual depending on their size, activity level, and the
amount of water present in the foods they eat each day.
However, the take home message is simple – pay attention to
thirst and drink when you are thirsty and try to stick with good ole H20 rather
than juice or soda. It is what your
body needs without all the extra calories!
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