By Brierley Wright, M.S., R.D.
As a runner, I’ve always been an avid water drinker. And because I’m a dietitian and nutrition editor, I typically choose to hydrate with water (it’s calorie-free!) over other beverages like sweetened tea, soda or sports drinks, which can pack a hefty calorie and sugar punch. (That said, there is a time and place when nonwater drinks are worthy choices.
Still, I was surprised to learn just how essential water is for so many body processes. Here—as Rachael Moeller Gorman reported in EatingWell Magazine’s July/August issue—you can see what water does for your body, from your head to your toes.
Staying hydrated keeps your memory sharp, your mood stable and your motivation intact. When you’re well-hydrated, you can also think through a problem more easily. Researchers hypothesize that not having enough water could reduce oxygen flow to the brain or temporarily shrink neurons—or being thirsty could simply distract you.
Water keeps your throat and lips moist and prevents your mouth from feeling dry. Dry mouth can cause bad breath and/or an unpleasant taste—and can even promote cavities.
Dehydration lowers your blood volume, so your heart must work harder to pump the reduced amount of blood and get enough oxygen to your cells, which makes everyday activities like walking up stairs—as well as exercise—more difficult.
Your body releases heat by expanding blood vessels close to the skin’s surface (this is why your face gets red during exercise), resulting in more blood flow and more heat dissipated into the air. When you’re dehydrated, however, it takes a higher environmental temperature to trigger blood vessels to widen, so you stay hotter.
When you’re well hydrated, the water inside and outside the cells of contracting muscles provides adequate nutrients and removes waste efficiently so you perform better. Water is also important for lubricating joints. Contrary to popular belief, muscle cramps do not appear to be related to dehydration, but, instead, to muscle fatigue, according to Sam Cheuvront, Ph.D., an exercise physiologist for the U.S. Army Research Institute of Environmental Medicine.
When a person is severely dehydrated, skin is less elastic. This is different than dry skin, which is usually the result of soap, hot water and exposure to dry air. And, no, unfortunately, drinking lots of water won’t prevent wrinkles.
Your kidneys need water to filter waste from the blood and excrete it in urine. Keeping hydrated may also help prevent urinary tract infections and kidney stones. If you are severely dehydrated, your kidneys may stop working, causing toxins to build up in your body.
So now that you’ve read the total body benefits of drinking water, how much water do you actually need?
It isn’t eight 8-ounce glasses each day. The Institute of Medicine says adult men need about 13 cups (3 liters) per day of fluid; adult women need about 9 cups (2.2 liters) of fluid. (You get about an additional 2 1/2 cups of fluid from foods.)
“But one size doesn’t fit all,” says Leslie Bonci, R.D., C.S.S.D., director of sports nutrition at the Center for Sports Medicine at the University of Pittsburgh Medical Center and dietitian for the Pittsburgh Steelers. Your size and activity level affect your fluid requirements. Simply put, the larger and more active you are, the more you’ll need.
“The easiest thing that anybody could do on a daily basis is monitor their urine color,” says Douglas Casa, Ph.D., A.T.C., who studies hydration at the University of Connecticut. “Lighter urine color—like lemonade—means you’re generally well-hydrated. If it’s darker, like apple juice, you are most likely dehydrated.”
How much water do you drink every day?
Watch this video to learn how much water YOU should drink a day based upon your weight and activity level