Water, the most common substance on Earth, is also the nutrient that your body needs the most. Between 55 and 75 percent of adult body weight is water (about 10 to 12 gallons). Water is critical in regulating all body organs and temperature as well as dissolving solids and moving nutrients throughout the body. Research has shown that proper hydration may minimize chronic pains such as rheumatoid arthritis, lower back pain, migraines, and colitis as well as lower cholesterol and blood pressure. Because water is naturally low in sodium, has no fat, cholesterol or caffeine and isn't flushed straight through the body like many other beverages, it's the natural solution that your body chooses to help reach its daily fluid quota.
Believe it or not, humans lose a pint or more of water every day simply by breathing! Humans normally lose about 10 cups of fluid a day in exhaled air, perspiration, and other bodily secretions. What is lost must be replaced to maintain a fluid balance. Don't wait until you're thirsty to pour a glass of water. By the time you feel thirsty, you've probably already lost 2 or more cups of your total body water.
The right amount of water is essential for keeping your body functioning. The average person only consumes six 8-ounce servings of water a day. This is well below the recommended eight servings. How much you really need to drink depends on your body size, activity level and the air temperature. To determine your ideal daily water intake, experts at the Mayo Clinic suggest dividing your weight in half and using this number as the ounces of water you should consume. Going off of this formula, a 125-pound person should indeed consume the recommended eight servings of water each day; however, someone who weighs 175 pounds should aim for eleven servings. If you are physically active, the American Dietetic Association recommends adding one to three cups of water to your daily diet for each hour of physical activity.
Once you start exercising, don't stop drinking water. Thirst is not always an adequate indicator of the body's need for fluid replenishment during exercise. Studies show that during vigorous exercise, an important amount of fluid reserves may be lost before you are aware of thirst. During exercise, it's recommended to replenish fluids at least every 20 minutes. You should also drink plenty of water before and after you exercise, regardless of thirst.
That headachy feeling you may be experiencing at the end of the day may very well be a sign of dehydration. Because the brain is made up of 75% water, moderate dehydration can often cause lightheadedness, dizziness, headaches and nausea. More severe dehydration may also raise the body's core temperature, effect muscle strength, endurance and coordination as well as increase the risk of cramps, heat exhaustion and life-threatening heat stroke. One of the best ways to recognize dehydration is to pay close attention to the color of your urine—ideally, light to clear urine indicates proper water intake.