Betty Greer,Ph.D., R.D.
Family and Consumer Sciences
Important for Life
ater makes up approximately twothirds of the body’s weight and approximately 75 percent of the
brain’s weight. Nearly 4 percent of the water
in the body is lost through the skin, lungs and
through urine and stools each day. This water
loss must be replaced continually by beverage and food consumption. Sweating causes greater water loss and increases the need to
consume more fluids.
Water loss resulting in as little as 1 percent
decrease in body weight is called dehydration.
Dehydration will reduce the body’s ability
to perform physically and mentally. Infants
and children can quickly become dehydrated;
therefore, it is critical they consume adequate
fluids. Water is so important to well-being that
you can only live a few days without it.
Why Is Water So Important?
It makes up a large part of the body and plays
a role in nearly every function of the body:
Water is essential for the body to cool
itself. The inability of the body to cool
itself will result in heat cramps, heat
exhaustion or a heat stroke.
is needed for digesting, absorbing
and transporting nutrients.
is a lubricant for joints and
cushions vital organs and tissues. It is
important for healthy mucus membranes
in the lining of the mouth, lungs, nose
helps prevent constipation (and
possibly reduce the risk of colon cancer)
by adding bulk to feces and moving it
through the colon faster. Getting enough
fluid is critical with a high-fiber diet to
keep the bowels functioning properly.
Water is critical for health because it
carries waste products from cells so the
waste can be excreted from the body.
How Much Water Do You Need?
The average male needs
approximately 12 cups
of water per day, and the
average female needs
cups. The following are
factors that increase the
amount of fluid you need:
• high temperature
• low humidity
• high altitude
• high-fiber diet
• increased fluid losses as a result of
diarrhea or vomiting
• caffeine or alcohol consumption
(Alcohol and caffeine are diuretics
which means they cause water loss and
could increase the risk of dehydration.)
Heat Cramps, Heat Exhaustion and
Heat cramps usually occur when profuse
(or heavy sweating) causes a loss of body
salt. The cramps occur in muscles usually
in the abdomen and the extremities. They
consist of a contraction
of the muscle for one
to three minutes,
and they move
down the muscle
from one group of
muscles to another.
pain. Heat cramps
may be a complication
of heat exhaustion but
may appear alone without other
symptoms of dehydration. The key to preventing heat cramps is to drink enough water. Avoid salt tablets because they may increase
water loss and increase the risk of heat-related problems.
The symptoms of heat exhaustion are
headache; rapid pulse; weakness; a pale, cool,
moist skin; and fatigue. If left untreated, it
may lead to a heat stroke.
A heat stroke is serious and often lifethreatening. When a heat stroke occurs, the body generally stops sweating, causing the
body temperature to rise dangerously high.
Other symptoms include dizziness, increased
weakness, delirium, and hot, dry skin. A heat
stroke can lead to death.
What Are Good Water Sources?
Water is important. However, many foods
are primarily water and help meet your total
water needs. Therefore, eating a well-balanced
diet will help meet water needs. The following
foods are almost all water:
• fruit and vegetable juices
• prepared gelatin
Many foods that
are called “solid” also
contain high levels of
• Many fruits and vegetables are over 80
• Prepared grain products may be up to
30 percent water.
References: Benardot, D. 1992. Sports Nutrition. The
American Dietetic Association.
Sherman W.M. 1996. American College
of Sports Medicine position
Kleiner S.M. 1999. “Water: An essential but
overlooked nutrient.” Journal of the American
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