Water, water everywhere

By: Michelle Morra-Carlisle Jul 05, 2010
  Article

The human body is mostly water. Here's why you need to drink more of it.

It’s wet in there. Water accounts for half of our body weight, and we need that water to perform several tasks.

Water regulates our body temperature and cools us when we sweat. It transports nutrients throughout the body, allows us to digest our food and removes waste products. Water also cushions our organs, lubricates our joints and sends electrical signals between nerves and muscles so that our muscles can move. It even carries signals to our brain cells so that the brain can function.

Not only do we use water, we lose it – when we sweat, and through breathing, urinating and defecating. To keep the body functioning, we need to continually replenish the fluid.

How to stay hydrated

Women need about 11 cups of water per day, according to Natalie Walsh, a Toronto-based dietitian, and that amount increases to 12 cups during pregnancy and 15 cups during breastfeeding. Men need about 15 cups a day. For children, Walsh recommends six cups per day for those aged one to eight years; 10-13 cups per day for boys aged nine to 18 years, and eight to nine cups per day for girls aged 9 to 18 years. Pure water is best but there are other sources, too.

“People get about 80 per cent of their water needs from fluids; 20 per cent from foods, especially fruits and vegetables (watermelon and tomatoes are more than 90 per cent water by weight),” says Walsh. “Besides water, other fluids can include milk, juice, sports drinks, soft drinks, coffee or tea.”

While caffeinated beverages do contribute to hydration, people should consume them only in moderate amounts because caffeine is a stimulant. Carbonated beverages are not a good way to stay hydrated – since the bubbles create a false sense of fullness – and are best avoided.

The tricky part is remembering to drink water. Our natural “drink when thirsty” response isn’t enough, especially in the summer months.

“Thirst alone isn’t a good indicator of when to drink,” says Walsh, "because by the time the thirst mechanism sets in, you’re already slightly dehydrated and have already lost about one per cent of your body weight in fluid.”

To stay ahead of the game, she offers these suggestions:

  • Carry a reusable water bottle with you – it’s environmentally friendly and will remind you to drink throughout the day.
  • Eat seven to 10 servings of fruits and vegetables per day.
  • Sip water during exercise or use a sports drink if exercise is intense or lasts longer than one hour.

What happens when we dehydrate?

Think of a plant that wilts when it hasn’t been watered, or a car engine that seizes up when it lacks oil. For the human body, too, things start to go wrong when we lack fluid.

“If we’re not getting enough water, the first two symptoms are thirst and decreased urine output,” says Walsh. “If you’re producing a small volume of dark yellow or apple-juice-coloured urine with a strong smell, you’re dehydrated.” (In contrast, urine from a well-hydrated body should be “clear and copious.”)

More severe dehydration produces symptoms such as dizziness, fatigue, headache, muscle cramps, nausea, chills, tingling hands and feet, and/or an increase in core body temperature.

What about electrolytes?

There may be times when water is not enough to rehydrate the body. When we sweat a lot because of heat and humidity, or intense and long-lasting exercise, our bodies lose not only water but electrolytes (minerals like sodium, potassium and chlorine). Walsh recommends electrolyte replacement drinks, also known as sports drinks, in these scenarios:

  • During and after intense physical exercise that lasts for over one hour;
  • When wearing protective equipment (such as a helmet, or other gear) while playing sports or in the workplace.
  • In hot and humid weather.
  • When you notice salt stains on your clothes – a telltale sign of electrolyte loss due to sweat.

Electrolyte replacement drinks should be tasty and non-carbonated. They should not contain herbal ingredients or caffeine.

Michelle Morra-Carlisle has written professionally for almost 20 years, at a federal government agency, for a trade magazine publisher and most recently as a freelancer. She enjoys the ever-changing nature of freelance work and the variety of topics she gets to cover - from jewellery design to schizophrenia - and has won several awards for her articles. Michelle is especially pleased to be covering health, fitness and wellness for Primacy.ca and says that with each article, she picks up valuable tips for improving her own health and lifestyle.