The Truth About Water

Water – you can’t live without it. In fact, 50-70 percent of your body is comprised of water, which works to lubricate tissues, carry nutrients to your cells and waste products away from them, and regulate your body temperature by cooling you off when you’re too hot.

But while there’s no debate among health professionals that fluids are essential for life, there are a variety of claims about water that just aren’t borne of scientific research. Here are a few myths and their realities:

Myth: Everyone should drink eight 8-ounce glasses of water a day.

Reality: “Nonsense,” says Stanley Goldfarb, MD, FACP, nephrologist and Professor of Medicine at the Hospital of the University of Pennsylvania. “There’s no question that people in hot, dry climates or those who have certain medical conditions like kidney stones have an increased need for water. And if you’re exercising vigorously, you need to replace fluids lost through sweat. But average, healthy people don’t need to drink a lot of extra fluids.”

According to Goldfarb, you lose about 2-3 quarts of water a day through body processes such as breathing, sweating, and urination. This fluid loss can be replaced by drinking a variety of beverages, including milk and even caffeinated drinks – in moderation. While coffee and colas have a mild diuretic effect, the end result is that you retain nearly as much fluid with caffeinated drinks as you do with water. And water-loaded food sources, such as cucumbers, watermelon, tomatoes, and zucchini provide about half of the fluids you need daily.

Myth: You should drink lots of fluids before, during and after exercise – even if you’re not thirsty.

Reality: “Fluid needs vary from individual to individual and depend upon what you’re doing and whether you’re doing it inside or outside,” says James Muntz, MD and team doctor for the Houston Texans (NFL), Rockets (NBA) and Astros (MLB). And while you should hydrate before, during and after exercise, says Muntz, “thirst should be your guide.”

According to updated recommendations by the International Marathon Medical Directors Association (IMMDA), “Drinking to thirst is the body’s dynamic physiologic fluid calculator and in most cases will protect athletes from the hazards of both over and under drinking.” In other words, you don’t need to drink fluids just because you think you should or because there’s a water station and others are drinking. Drink when you’re thirsty and don’t drink when you’re not thirsty.

Myth: Sports drinks are always better than water when you’re exercising.

Reality: A good rule of thumb, says Muntz, is that if you’re working out strenuously for longer than 30 minutes or exercising in very high temperatures, you should drink sports drinks to help replace sodium lost through sweat and restore carbohydrates needed for energy. Older athletes may also need the sodium found in sports drinks while exercising because of age-related changes in sodium balance. Young healthy adults who are exercising lightly or moderately for 30 minutes or less, though, can adequately replenish fluid losses with water.

Myth: You can never drink too much water.

Reality: Yes, you can, says Goldfarb, “There’s more harm done by over drinking during an athletic event than by under drinking.” Drinking too much fluid can dilute the concentration of sodium in your blood and cause a condition called hyponatremia. This can result in severe symptoms such as confusion, muscle cramps, seizures or even loss of consciousness.

Hyponatremia can be avoided by following your body’s cues and drinking only when you’re thirsty during endurance events.

Myth: Drinking a lot of water suppresses the appetite.

Reality: As much as you may want this to be so, this is only true in the short term. “Drinking a lot of water may fill you up for a short period of time,” says Goldfarb. “But water moves through the gastrointestinal tract so quickly that the appetite suppressant effect doesn’t last very long.”

Myth: Fluid calculators/charts or weighing yourself pre and post exercise is the gold standard for determining fluid replacement needs.

Reality: While fluid calculators or charts can provide an estimate of body fluid losses for fluid replacement, athletes should defer to physiologic cues, such as thirst or concentrated urine (need to increase fluid intake) or dilute urine and bloating (need to decrease fluid intake). This is because charts and fluid calculators don’t take into account changes in ambient conditions or workout conditions, which change your sweat rate.

The bottom line? Whether from tap, fountain or bottle, water is the ideal drink. It’s calorie-free, inexpensive, and readily available. But the key thing to remember when it comes to water intake is to understand that you don’t need to force yourself to drink a certain amount – it’s more important to pay attention to your body and act accordingly. “Do what comes naturally,” says Goldfarb.

By Linda Hepler, BSN, RN