Water Works.

Do you drink enough water? If you don't, you're affecting almost every aspect of your health.

Water provides true refreshment for the thirsty, but most people don't know that it also plays a vital role in all bodily processes. Unfortunately, most people don't drink enough water, perhaps because they don't realize just how important it is. The fact is, not drinking enough water affects every aspect of your body, right out to your skin.

Essential for Life

Although deficiencies of other nutrients can be sustained for months or even years, a person can survive only a few days without water. Experts rank water second only to oxygen as essential for life.

Water supplies the medium in which your body's various chemical changes occur, aiding in digestion, absorption, circulation, and lubrication of body joints. Water is used for virtually all bodily functions, including carrying nutrients and oxygen around the body and eliminating waste.

Water maintains body temperature through perspiration. It helps cushion joints and protect organs and tissue. Even your skin is affected. Since your body's major internal organs snatch up water first, skin gets only what's left--if there is any. When you stay well hydrated, however, skin stays supple overall and plumped up, lessening the visibility of fine lines and wrinkles.

Water constitutes about 90 percent of your blood; 75 percent of your brain and muscles; 25 percent of body fat, and 22 percent of bone. Males have a higher percentage of body water on average than females because they tend to have less body fat.

Benefits of Water

Water promotes good health in many ways, from reducing the risk of certain cancers to improving short-term memory and weight loss. For example, in a 10-year study of nearly 48,000 men, those who drank six eight-ounce glasses of water daily were half as likely to develop bladder cancer as those who drank just a glass a day. Although the study included only men (who run a higher risk of bladder cancer than women), drinking plenty of water and other fluids may well protect both sexes, says the study's lead author, Dominique Michaud, a researcher at the Harvard School of Public Health in Boston.

Not drinking enough water can also make you fat. When you don't drink enough water, your body secretes a hormone, aldosterone, that causes tissues to hold on to almost every molecule of liquid water retention. New research shows that a decrease in water may cause your body's fat deposits to increase.

Another side effect of hidden thirst is that you may think you're hungry when you're actually thirsty. Drinking water throughout the day keeps your stomach feeling full and reduces the desire to eat. The colder the beverage, the greater its fat-burning power. Maximize calorie burn by keeping the water ice-cold.

Kimberly Myers found this out after years of struggling to lose weight. "I could never figure out why I was always so hungry," Kimberly says. "But several months ago I read about how water deprivation can make you think you're hungry when you're not. I was skeptical, but I decided to give it a shot. I increased my water intake more than double of what it had been, and I no longer feel hungry all the time. The pounds have also been coming off consistently, and I feel better overall."

In a two-year project (funded by the Brita Products Company) Susan Kleiner, nutritionalist and assistant professor at the University of Washington, pulled together findings from more than 150 studies worldwide to present the most complete picture to date of the impact of hydration on health. "While we've long known the effects of severe dehydration, we're now beginning to understand the impact of chronic mild dehydration on health and performance."

Although more research is needed, Kleiner reports that one key study conducted at the Centre for Human Nutrition at the University of Sheffield in the United Kingdom found that water drinkers reduced their risk of breast cancer by 79 percent.

In a separate study conducted at the Fred Hutchinson Cancer Research Center in Seattle, Washington, researchers monitored women who drank more than five glasses of water a day and found that their risk of colon cancer was reduced by 45 percent.

According to Kleiner, research now shows that dehydration can trigger mitral valve prolapse--an irregular heartbeat--in women with the characteristic tall, thin body type associated with the disease. Kleiner reports that when the women in this study were rehydrated, their heartbeats returned to normal.

In a study conducted at the Defence Institute of Physiology and Allied Sciences, Delhi Cantt, India, Dr. Kleiner reports they found that a 2 percent loss of body fluid affected short-term memory and reduced the ability to add and subtract.

So How Much Is Enough?

While thirst signals the body's need for fluid, slight dehydration has already occurred by the time a person becomes thirsty. It only takes a loss of 1 to 2 percent of the body's total water content to cause dehydration. On average, you lose 10 cups of water a day and get only four back from your food. Each day a person will lose a minimum of 400 milligrams (about 1 1/2 (cups) of water through breathing, 400 milligrams through the skin, and 1,000 milligrams (4 cups) through the kidneys. (This is the minimum, so if you're active you'll lose more.)

The amount of water inside a cell, known as the cellular hydration state, can change within minutes. When you begin to lose as little as 1 percent of your body weight in water, your ability to regulate heat begins to be impaired. If you lose 7 percent of your body weight in water, you're likely to collapse when exercising in heat. If you dehydrate a muscle by as little as 3 percent, you can cause a loss in contractile strength of about 10 percent as well as a 12 percent loss in speed.

According to the American Dietetic Association, it's not eight glasses of water a day; it's eight eight-ounce servings--big difference. However, those eight cups are just a guideline. For instance, you should add a cup if you exercise, live in a warm climate, or drink more than two cups of coffee or alcohol a day, since these drinks act as a diuretic. Air travel and working in a climate-controlled office also adds a cup or two. And while some fruits and vegetables are as much as 95 percent water, these can't be included in your daily intake, because the eight cups were calculated assuming you eat plenty of fruits and vegetables.

Fully rehydrating the body doesn't occur as fast as you might think. Even after consuming large amounts of water, your dehydrated body can take from a few hours to a day or more to completely rehydrate. Tissues such as the muscles and skin, which are predominantly water, take the longest to recover from dehydration. A good sign is if you urinate every two to four hours, and your urine is clear or light in color.

Most people take water for granted, not realizing how desperately their bodies crave it. Don't wait until the tap runs dry to realize how important water is; start today replenishing your body, and begin to reap its many rewards.

Tammy Darling is a writer living in Three Springs, Pennsylvania.