Hydrate for good health: drinking when you're thirsty is not enough. find out why your body needs fluid and learn how to make sure you're getting the right amount

It's a hot summer day and you're thirsty--very thirsty. Just drink a glass of water and the problem is solved, right? Not so fast. According to W. Larry Kenney, PhD, president of the American College of Sports Medicine, "Thirst alone is not the best indicator of dehydration or the body's fluid needs."

When you drink to quench your thirst, you are not satisfying your total fluid needs. "Unfortunately, our brain signals us after it is too late," says Susan Ryan, MD, an emergency room physician in Denver, CO. According to Ryan, "Most people don't drink enough water and therefore are not operating at peak efficiency."

Your Body's Cries for Water

The human body is made up of approximately two-thirds water. About 75 percent of the brain is water, and water makes up 75 percent of muscle and more than 90 percent of blood. As a result, nearly every bodily function depends on water, including the transportation of oxygen and nutrients to cells, regulation of body temperature, and lubrication and cushioning of joints and key organs.

Brain function, immunity and elimination all rely on water. Water even helps us breathe. Having youthful skin also requires proper hydration.

"Dehydrated skin is a common problem," explains Myra Eby, president and founder of MyChelle Dermaceuticals, a Frisco, CO-based manufacturer of nontoxic skin care products. "A key cause of aging skin is lack of moisture. In order to have supple, soft skin, you need to drink plenty of fresh water frequently throughout the day," she says.

Water is especially beneficial to weekend warriors, exercisers and athletes. According to Ryan, studies demonstrate that as little as 2 percent dehydration significantly decreases athletic performance. "I have found that even sedentary people have improved vitality after they increase their daily water intake," she says.

Symptoms of dehydration include fatigue, mild nausea, headaches and dizziness. "In more profound states, we see weakness, increased heart rate or serious confusion," says Ryan. "Children, the elderly, people who exercise and people living in hot, humid climates may have a greater risk of dehydration." One of the best ways to tell if you are dehydrated is by the color of your urine. As a general role, a well-hydrated body excretes lightly colored urine.

Staying Hydrated

About 80 percent of our fluid comes from water and other beverages, the other 20 percent comes from food. Many fruits and vegetables, including watermelon, oranges, cucumbers and lettuce, are good sources of fluid.

In 2004, the National Academy of Sciences reported that men need about 125 oz. and women need about 91 oz. of fluid each day. However, fluid needs depend upon many factors.

To quickly calculate your hydration needs, simply divide your body weight in half: that will be the number of ounces you need each day. For every 20 minutes of exercise, add 8 oz. to that number. For example, a 150-lb. person who walks 30 minutes a day at a medium pace (about 4 mph) should drink 87 oz. If that same person walks for 60 minutes, they need 99 oz. If you drink alcohol, drink as much water as alcohol to offset alcohol's dehydrating effects.

Healthful Beverage Choices

With a bevy of beverages filling the shelves, you may think it is easy to avoid dehydration. But drinking just any fluid is not the best way to stay hydrated. Coffee, for example, is dehydrating because of its high caffeine content. Sodas and some sports drinks contain a lot of sugar, which can negatively affect health on many levels.

Your best bet is filtered or bottled spring water. Water that provides additional electrolytes is also a good choice, especially if you perspire a lot. Electrolytes, such as calcium, potassium and magnesium, are important minerals that can become depleted when you are dehydrated.

Some brands add flavors to their water. Try a refreshing hint of peppermint or citrus flavor.

You can also go beyond basic hydration by choosing a high-quality tea beverage. Look for those containing the powerful antioxidant epigallocatechin gallate (EGCG), found in green tea. The best health-promoting bottled teas begin with high-quality filtered water and do not contain artificial flavorings, colorings or other chemicals.

It's important to make hydration a health priority. Choose your fluid sources carefully. Adding high-quality, natural iced tea or flavored water adds variety and may encourage you to drink more. Making healthy hydration choices is a refreshing way to enhance an active summer day.

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