Drinking too much water is bad for you??
I just came across this article this morning in the daily paper. I'm confused as I always thought drinking more water than required would be a benefit and not a downfall.
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Getting enough water? I'll drink to that
Your body loses a lot of fluids during a day and needs to replace them. But choose your sources wisely
LESLIE BECK
Globe and Mail Update
Read Bio | Latest Columns
July 11, 2007 at 8:39 AM EDT
We've all heard it's important to drink plenty of water, especially in the summer, to replenish the fluids lost due to heat and physical activities.
But if you wait until you're thirsty to reach for your water bottle, chances are you're already becoming dehydrated.
Losing as little as 1 to 2 per cent of your body weight from fluids can impair your physical performance and your ability to think, not to mention increase your risk for heat stroke.
Normally, an average adult loses more than 10 cups (roughly 2.5 litres) of water each day just by breathing, sweating and excreting wastes. When it's hot outside, your body loses even more water through sweat, especially if you're active. For instance, an hour of singles tennis can drain one to 2.5 litres of water from your body, and a round of golf as many as four litres.
Water is the most abundant compound in the human body, making up roughly 60 per cent of our weight. Your body needs water to regulate its temperature, transport oxygen and nutrients to your cells, keep your skin moist and cushion your joints.
Water can keep you healthy in other ways, too. Research suggests that drinking adequate water can guard against kidney stones, constipation, some cancers and possibly heart disease.
Because your body is constantly losing water, you need to replace it by drinking fluids and, to a lesser degree, eating watery foods such as fruit and vegetables. If you don't consume enough fluids to replace losses, you'll start to feel dizzy, lightheaded or fatigued, and may get a headache and develop muscle cramps.
Other signs of mild to moderate dehydration include thirst, decreased urine output, flushed skin, dry mouth and eyes, nausea and loss of appetite. A child's irritability on a hot day may also indicate he or she is dehydrated.
If dehydration progresses, extreme thirst, lack of sweating, low blood pressure, rapid heartbeat, muscle spasms and heat injury can occur. At its most serious, it can lead to life-threatening heat stroke.
Some people are at greater risk of suffering the effects of dehydration. Young children, older adults, people working outdoors in hot weather and people with poorly controlled diabetes or other chronic illnesses are more susceptible to becoming dehydrated.
And there's the exercise factor. If you don't drink enough before, during and after exercise, your heart beats harder, your body temperature rises and, ultimately, your performance suffers.
But it is possible, if uncommon, to have too much of a good thing.
If you drink too much water, the kidneys can't keep up and are unable to excrete the excess. Your blood becomes diluted, resulting in low blood sodium (hyponatremia), which can lead to swelling of the brain.
Even if you drink a lot of water, you're unlikely to experience hyponatremia as long as you do it over the course of the day as opposed to drinking an enormous volume at one time. Endurance athletes such as marathon runners and triathletes, who drink large amounts of water, are at greater risk.
It turns out that all beverages - excluding alcoholic ones - count toward your daily water requirements: water, fruit juice, milk, soy beverages, soft drinks, even coffee and tea.
(While older studies demonstrated caffeine to have a weak, short-term diuretic effect, recent studies do not. The body adjusts to caffeine within five days of regular use, greatly reducing its mild effect of fluid loss.)
Even so, there are some better fluid choices, particularly if you're counting calories. Research suggests that we don't register the calories we drink as well as the ones we eat.
A U.S. research panel reviewed studies on beverages and health, and has proposed a guide for choosing what to drink. Published last year in the American Journal of Clinical Nutrition, the "beverage guidance system" ranks drinks based on their calorie and nutrient content.
Plain water outranked all other beverages because it has no calories, no sugar, no sodium and may provide some calcium, magnesium and fluoride.
Water was followed by, in order, unsweetened coffee and tea, low-fat milk and soy beverages, diet drinks, calorie beverages with some nutrients (fruit juices, sports drinks) and sugary beverages (soft drinks, fruit drinks).
To avoid consuming too many calories from beverages, the panel recommends limiting drinks to at most 10 per cent of daily calories. In other words, you shouldn't sip more than 200 calories, if you follow a 2,000-calorie diet.
Leslie Beck, a Toronto-based
dietitian at the Medcan Clinic,
is on CTV's Canada AM every Wednesday. Visit her website at lesliebeck.com.
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How much to drink
The U.S.-based Institute of Medicine of the National Academy of Sciences recommends the following daily intake of water:
Adult men: 13 cups (3.2 litres);
Adult women: nine cups (2.2 litres);
Children ages 4 to 8: five cups (1.2 litres);
Children ages 9 to 13: eight cups (two litres);
Teenaged girls: eight cups (two litres);
Teenaged boys: 11 cups (2.6 litres);
Pregnant women: add one cup (250 millilitres);
Breastfeeding women: add four cups (one litre).
When exercising
Before: two cups (500 ml) fluids;
During: one-half to one cup (125 to 250 ml) fluids every 15 to 20 minutes. Sports drinks are recommended if exercising longer than an hour;
After: Two cups (500 ml) fluids for every pound of body weight lost.
Leslie Beck
How to fight fluid loss
Know the signs of dehydration.
Have a glass of water when you first get up.
Drink fluids with each meal and throughout the day.
Keep a pitcher of water on your desk as a reminder.
If you don't like plain water, flavour it with a splash of blueberry or pomegranate juice. Or add a slice of lemon.
When you travel, carry a bottle of water with you.
Have a water bottle handy when you exercise.
Leslie Beck