Everyone has heard the advice to drink 8 glasses of water each day. Water relieves thirst, maintains electrolyte balance, and regulates nearly every body system. When there is too little fluid in the body, salt concentrations increase and cells emit water to balance things out. When the cells are dehydrated, you feel thirsty.

Since we only feel thirsty when we're already dehydrated, we need to drink often. 8 glasses of water a day will usually replace the water lost during sweating and digestion; depending on your activity level, age, and weight, you may need more or less.

If you feel tired or headachy in the afternoon, you may be feeling the effects of dehydration. If your urine is very pale or clear you're probably getting enough water; the darker your urine, the more dehydrated you are. If you can't remember to drink your water, use memory aids such as a water log (make a tally mark for each glass consumed), or start the day with eight bottles of water and work through them. If you don't like water, try serving it with ice or a lemon wedge, or drink flavoured (sugar-free) water.

Adding more watery foods, such as watermelon, to your diet will also help hydrate you. Other beverages such as milk and juice can be considered a small part of your water intake, but caffeinated beverages will dehydrate you and increase your water needs. Make sure to drink extra water during exercise, hot weather, and when you're sick.

Marlene Veloso