Dr. Neal Pinckney
Because it has no calories, you might not
think water would be an essential element in nutrition and in reducing
the risk of heart attack, but it is a highly important aspect of health.
Among its many functions, water keeps our kidneys functioning
efficiently. When the kidneys cannot do their job properly, the liver
must take on some of that task and if this happens it cannot metabolize
fat into energy as well. Water also aids in digestion, carries
nutrients, aids in building tissue, transports waste from the body and
helps maintain the body's normal temperature.
About 60% of a person's weight is made up
of water. A fluid loss of as little as 2% of body weight can affect
physical performance. A 5% loss can cause stomach and muscle cramps.
Heat stroke, which can be fatal, often occurs at 7% to 10% fluid loss.
Although there are large amounts of water in vegetables and fruit, which
is helpful to vegetarians, anyone who consumes high levels of fiber
should be sure to consume sufficient water.
Contrary to what many people think, a
good way to combat excess fluid retention is to drink water. When the
body doesn't get enough water, it conserves all the moisture it can. The
extracellular spaces it is stored in (swollen feet, hands and legs)
hoard the water until the threat of dehydration is no longer sensed. The
best way to tell your body to release the stored fluids is to give it
water. Salt can cause higher water retention, requiring extra water to
dilute it. Lowering salt intake is easy to do and extra amounts of water
will flush the sodium from the system.
Thirst is not always a good indication of
the need for water. In many people, the sensation of thirst doesn't
occur until the body is already dangerously dehydrated. The best way to
assure a proper fluid balance for an average size person is to drink at
least 6 to 8 eight ounce glasses of water a day. Heavier people need to
drink even more water. A half-hour heavy workout can produce as much as
three quarts of sweat, a 4% fluid loss for a 150 pound person. That loss
needs to be replaced. Beyond the basic 6 to 8 cups of water a day, for
each 100 pounds of body weight, an additional 8 ounce cup of water
should be taken for each hour of light exercise, 12 ounces (1 cups) for
moderate exercise and 20 ounces (2 cups) of water for each hour of
Plain cool (not iced) water is the best
way of replacing fluid loss. Fruit juice, mixed half and half with
water, or sports drinks with not more than 10% carbohydrate
concentration are also good. High-carbohydrate sports drinks (more than
24 grams of carbohydrate per eight ounces) are not advised. Sodas,
undiluted fruit juices and high-carbohydrate drinks actually slow down
absorption and do not allow immediate fluid replacement.
In exercise that lasts up to 1 hour,
taking small sips of water or low-carbohydrate sports drinks is often
helpful, but it is better to avoid drinking large amounts while
exercising. For marathons and long exercise sessions, larger quantities
of fluids are needed. For longer events, a good test is to weigh
yourself before and after. For each pound of weight loss, you should
drink 16 ounces (2 cups) of water.
Some drinks, such as coffee and tea, can
increase fluid loss because they have a diuretic effect. Alcohol is a
stronger diuretic; the body needs eight ounces of water to replace the
loss from just one ounce of pure alcohol. Hot weather and low humidity
can add to the dehydration effect. Almost all foods contain water, but
they also may contain carbohydrates, protein and fiber, which increases
the need for water. Vegetables range from 70% to 90% water and can be
used as a part of the 6 to 8 cups of water needed daily.
If you decide to suddenly increase your
water intake, you may find that it will take two or three weeks for your
system to become accustomed to the change. You'll likely make more
frequent trips to the bathroom for a week or two, but your bladder will
gradually become used to handling the increased flow, and your routine
will soon return to normal.
Water is not a substitute for foods, but
it can help you avoid the temptation of high calorie or high fat
offerings, especially when you're away from home. A large glass of water
just before you are tempted may help you control your craving.