With the official start of summer less than one week away, it's time to pay more attention to your fluid intake. So, how much water do you need to drink each day? What seems like a simple question doesn't have a straightforward answer. While many experts recommend eight or more glasses, others contend you need to drink water only when thirsty.
In truth, water needs vary among individuals. How much you need depends on your age, your health, how active you are, the weather and your diet. And depending on what you drink, you could be doing your body more harm than good.
There's no question water is essential to your health. Water makes up roughly 60 per cent of our body weight. It's needed to regulate body temperature, transport oxygen and nutrients to cells, flush toxins from organs, keep your skin moist and cushion your joints.
Drinking enough water also helps prevent kidney stones by flushing away chemicals that form stones in the kidneys.
If your body loses too much fluid, or you don't drink enough water, or both, dehydration will follow. Young children are more vulnerable than adults because they have smaller fluid reserves and are less likely to drink enough during exercise in hot weather.
The elderly are also at increased risk because they may be less aware of thirst or on medications that amplify the effects of dehydration.
Warning signs include fatigue, loss of appetite, flushed skin, heat intolerance, light-headedness, dry mouth and dark urine with a strong odour. But even mild dehydration can cause headaches, zap energy, decrease mental alertness and lead to constipation.
Under normal circumstances, most of us can trust our sense of thirst to prevent dehydration. Research shows that most people meet their hydration needs simply by drinking fluids with meals and when thirsty.
Drinking too much water can be dangerous. Hyponatremia, or water intoxication, is a condition when blood sodium falls to an abnormally low level, prompting rapid swelling of the brain that can result in coma and death. Endurance athletes who drink large amounts of plain water in a short period of time are at greater risk.
The most recent dietary recommendations, published by the U.S.-based Institute of Medicine in 2004, state that healthy women who live in temperate climates need 2.7 litres of water a day to stay adequately hydrated, and men need 3.7 litres.
But that doesn't all have to come from the kitchen tap. Roughly 20 per cent of the water we consume each day comes from food. Fruits and vegetables owe at least three quarters of their weight to water. Cooked pasta is 66 per cent water.
The rest of our water needs to come from beverages. Men should drink 3 litres (almost 13 cups) of water each day and women need 2.2 litres (just over 9 cups). Children aged 1 to 3 need 1 litre (4 cups) daily and 4-to-8-year-olds 1.3 litres (5.5 cups). Teenagers need to drink more - about 1.8 litres (7 cups) for girls and 2.6 litres (10.5 cups) for boys.
These guidelines don't apply to people engaging in moderate or vigorous exercise and they don't account for hot weather, two factors that drive up the body's need for water. Women who are pregnant need an additional 1 cup of water each day; breastfeeding women require an extra 4 cups.
This might sound like a lot until you consider that everything you drink - excluding alcoholic beverages - counts toward your daily water requirements. Once you factor in coffee or tea, fruit juice at breakfast, milk on cereal, sports drinks, even soft drinks, you're probably doing better than you think.
(Alcohol is a diuretic, meaning it causes your body to lose water. Caffeine has a relatively mild diuretic effect that appears to diminish with daily consumption.)
Even so, not all beverages are created equal despite their ability to keep you hydrated. Use the following guide to hydrate without consuming excess calories, sodium or additives.
Choose water first
Your best choice is water - it's free of calories, sugar, sodium, colouring and preservatives. If you don't like plain water, add a slice of lemon, lime or orange for flavour, or a splash of blueberry, pomegranate or cranberry juice to make it more interesting.
Consider carbonated water if you find still water boring. (Contrary to popular belief, Perrier water is essentially sodium free - only 2 milligrams per 250 ml serving.) Keep a bottle filled with water and keep it with you - at your desk, at home, or in the car. Sip it slowly during the day; avoid gulping water quickly to prevent too many trips to the washroom.
Drink water during meals
Sipping on water between bites will increase your fluid intake and slow your eating pace. You might even find yourself eating less before feeling full.
Get kids used to drinking water so they don't drink flavoured drinks all the time. Keep a pitcher of water on the dinner table.
Limit fruit juice
There's nothing wrong with drinking a small glass of pure fruit juice at breakfast to add vitamins and minerals to your meal. But if juice is your main source of water, you're probably consuming more sugar - and calories - than you realize: 16 ounces (500 ml) of juice supplies roughly 220 calories, 50 grams of sugar and only 1 gram of fibre.
Avoid sugary drinks
Aside from their hefty dose of refined sugar (9 teaspoons per 355 ml can), soft drinks also contain chemical additives to flavour and preserve. Colas - diet colas included - are made with phosphoric acid, which can deplete calcium from bones if consumed in excess.
Other sugary drinks to reserve for a once-in-a-while treat include iced tea, lemonade, fruit punches and vitamin waters. Glaceau's Vitaminwater, for example, serves up 8 teaspoons of sugar per 591 ml serving.
Sweet coffee drinks are dessert, not something to quench your thirst. While Starbucks' Frappuccinos and Tim Hortons's Iced Capps supply calcium-rich milk, they're not easy on your waistline. A Grande Caramel Frappuccino contains 380 calories, 12 teaspoons of sugar and 9 grams of saturated fat.
Use sports drinks wisely
Sports drinks such as Gatorade and Powerade are intended to be used for exercise that lasts longer than an hour. They provide sodium to prevent hyponatremia during prolonged exercise. Most also contain liquid sugar and/or high-fructose corn syrup to provide energy for working muscles.
Guzzling sports drinks without exercising will boost your intake of sugar and sodium. Prolonged consumption has also been linked to tooth erosion.
Leslie Beck, a Toronto-based dietitian at the Medcan Clinic, is on CTV's Canada AM every Wednesday. Her website is lesliebeck.com.