The water you drink is as important as the food you eat. That's because more than half of your body is water--40-50 quarts if it was bottled. The 2-3 quarts lost daily through perspiration, urine, and breath need to be replaced. A reduction of as little as 3% of your body weight can affect your strength and endurance, 15%-20% water loss can be fatal.
In addition to the water that's in such foods as fruit, vegetables, and yogurt, you need to drink 6-8 glasses of liquid each day. Plain water is best. Caffeine-containing drinks (coffee, tea, cola) are diuretics that remove water from your body. Although such beverages as regular soft drinks, milkshakes, etc. provide liquid, in excess they contain too many calories and can create medical problems. Drink these in moderation.
You can't rely on thirst to tell when your water level is low. To make sure you get enough water when you exercise, weigh yourself before you start. Then drink fluids before and during your exercise. Weigh yourself again when you are done. Every 1 pound lost represents 2 cups of water that needs to be replaced.. Here are some ways water works.
Cools your body during exercise
Flushes out wastes
Carries nutrients to cells
Reduces risk of kidney stones
Promotes good skin tone
Decreases premenstrual bloating
Curbs appetite and snacking