Hydrating for Health

by Kelly James-Enger

HEY, YOU"RE COMMITTED to a healthy lifestyle. You make sure to eat plenty of fruits and vegetables and you’ve cut out most of the saturated fat in your diet. You watch your weight, exercise several times a week and even make time for meditation to keep your spirit as strong as the rest of you. Still, you may be neglecting an important component of your body’s health — your hydration.

Think about it. You may be able to recall what you ate yesterday, but can you remember what you drank? While water is a vital nutrient, the majority of Americans don’t consume the amount their bodies need — a survey conducted in 2000 found that over half drink less than eight 8-ounce glasses of water a day. And actually this common recommendation may be on the low side—if you work out regularly, you need even more fluid to replace what you lose during exercise.

If you short yourself on H2O, you may notice the results in the gym — dehydration can impair your exercise performance. Because our bodies need water to function normally, when you’re dehydrated you may also feel tired, have trouble concentrating or wind up eating more than usual since our bodies often misinterpret thirst as hunger. Taken to extremes, dehydration can even have life-threatening consequences.

why we need water

While there are countless books devoted to proper nutrition and effective exercise regimes, water is sometimes overlooked as an integral part of any fitness program. Part of the reason is that many people don’t realize water’s importance for good health, says Kristine L. Clark, Ph.D., director of sports nutrition department at Penn State University. “People don’t realize that water is one of the six classes of nutrients,” says Clark. “The average person thinks of water as an insignificant beverage and it’s very significant. It’s like a vitamin or mineral — if you don’t get enough of it, you’re really missing out.”

There are both health reasons and physical performance reasons that make proper hydration important to all adults and children, agrees Larry Armstrong, Ph.D., professor of environmental and exercise physiology at the University of Connecticut. “Our bodies are made up of 60% water by weight, and we need to maintain that water for proper functioning of our cells and our body organs,” says Armstrong. “For example, the circulatory system includes blood which is primarily water and the inside of our cells contains primarily water; thus, it’s important to replace the water each day.” Our bodies also use water to convert food into energy, remove waste, regulate body temperature, and carry nutrients and oxygen throughout our bodies.

Unfortunately, however, it’s easy to be dehydrated and not even realize it. “We have the ability to mask our thirst mechanism,” explains Clark. “And when we do feel thirsty, we’re already about 2% dehydrated so the feeling of thirstiness is actually a symptom of dehydration.” (Dehydration is measured in percentages relating to body weight—for example, a 150 pound person who is 1% dehydrated has lost 1.5pounds in water weight.)

Just how does the thirst mechanism work? Your brain reads the concentration of your blood constantly, and when your body water level has been reduced by about 1% or 2%, you’ll feel thirsty and presumably drink something. The problem is that people often don’t drink enough to make up the difference and maintain that 1-2% level of dehydration over time.

At the gym, this can translate into decreased performance. “When you lose about 1% of your body weight, your body begins to show the signs of the strain that it’s experiencing in terms of increased heart rate and increased core body temperature,” says Armstrong. “At 3% body weight loss, endurance performance begins to decline, and at approximately 5% body weight loss strength and power performance degrade.” Even mild dehydration can affect your day-to-day life as well — you may feel lightheaded, dizzy, tired, headachy or have trouble focusing or concentrating as well.

getting what you need

So how much water should you be drinking? It’s probably more than you think—the average sedentary person loses about 2.5 quarts of water a day through ordinary activity alone. And if you exercise, you lose between .8 and 1.5 quarts of fluid each hour in addition to that. All of this fluid must to replaced to maintain optimal hydration.

You’ve probably heard or read that people need eight 8-ounce glasses of water each day, but that’s not necessarily true. “That recommendation came from literature on weight management, but there are no studies proving that the average person needs eight 8-ounce glasses of water,” says Clark. In fact, your water needs are probably higher than this baseline. The American College of Sports Medicine recommends that people drink 14-22 ounces of fluid 2-3 hours before exercise; 6-12 ounces of fluid every 15-20 minutes during exercise; and 16-24 ounces of fluid for every pound of body weight lost during exercise.

While water is always a good bet, you needn’t rely only on H2O to satisfy your fluid needs. Beverages like tea, soda, coffee, and juice all contribute to your daily total as do foods like soup, fruits and vegetables that are naturally high in water content. Because beverages that contain caffeine or alcohol can be dehydrating, however, you’ll want to make sure that you drink plenty of water to offset your coffee or beer consumption.

There are two ways to easily monitor your own body water status. Weigh yourself first thing in the morning and before and after exercise; then drink a pint of fluid for each pound you lose during your workouts. Or simply pay attention to the volume and color of your urine—it should be straw-colored or pale yellow, says Armstrong.

Make it one of your fitness priorities to aim for optimal hydration. If you’ve been drinking too little, you may notice a marked improvement in the way you look and feel when you increase your water intake. Even if you don’t notice a difference, by drinking more water you’ll also be helping your body function at its best. •

from the July-August 2009 issue

People don't realize
that water is one of the
six classes of nutirents.