How Much Water Should You Really Drink?

When it comes to staying hydrated, many women follow the old rule of thumb: 8 glasses of water a day. But does that guideline really, excuse the pun, hold water? And what about sports drinks? Are they more or less effective than H20? Experts weigh in on the importance of hydration – as well as how, when and where to get the fluids your body needs…

Do you diligently keep a water bottle handy at all times – on your desk, inside the car, beside the bed – to ensure you stay hydrated with 64 ounces of water a day?

You don’t have to. It turns out the 8-cup rule may be unnecessary.

How much water is needed to stay healthy depends on you and your lifestyle, says Barbara Rolls, Ph.D., professor of Nutritional Sciences and the Helen A. Guthrie Chair in Nutrition at Pennsylvania State University.

“Some people are thirsty all the time,” she says. “And some don’t need much and don’t get thirsty often – and they’re just fine.”

Eight glasses of water a day “are recommended to ensure that Americans consume adequate fluid each day and avoid dehydration,” says Bob Murray, Ph.D., who has done research on exercise science and sports nutrition.

“On a cool day without physical activity, a woman’s fluid needs might be 1-2 quarts lower than on a warm day when she’s out and spends time at the gym,” he says.

So what’s sensible when it comes to your fluids needs? Here’s the lowdown on how to stay hydrated properly.

Why you should stay hydrated
Like oil lubricating a car, being properly hydrated improves your body’s performance.

“Even a slight amount of dehydration [hurts] how we think and feel because our bodies rely on fluid to support virtually every process,” Murray says.

About 60% of your body weight is water.

It maintains metabolic functions, including carrying nutrients to cells, eliminating wastes and regulating temperature.

Your body loses water from urine – about 6.3 cups a day – sweat, bowel movements and even breathing. Fortunately, people have a warning system: If you don’t get enough water, you won’t feel well.

How to recognize dehydration
Common signs you’re getting dehydrated include thirst, headaches and fatigue, says Murray.

Urine color is another good indicator.

If it’s dark yellow, you need more water. In fact, many people have darker urine in the morning, after not drinking anything for eight hours.

If you aren’t thirsty and produce odor-free urine that’s slightly yellow, you’re getting enough fluids, says Brendon McDermott, Ph.D., assistant professor and co-director of the Applied Physiology Laboratory at the University of Tennessee at Chattanooga.

“It should be light yellow to yellow, like lemonade,” he says. “Darker urine resembling iced tea indicates dehydration.”

Darker, more concentrated urine also can lead to other health problems.

That’s because it can leave bacteria behind in the urinary tract and trigger bladder irritations and urinary tract infections (UTIs), says Ariana Smith, M.D., urologist and assistant professor at the University of Pennsylvania in Philadelphia.

When to drink more water than usual
Sometimes, your body might need more water than usual – for example, when you're in a hot or humid climate, sweating more than normal, breathing more rapidly, or at high altitudes of more than 8,000 feet.

Other situations for drinking more water to stay hydrated include:

You’re prone to certain health conditions such as kidney stones. Water helps flush stones through the system.

You’re sick with fever, vomiting or diarrhea. Your body loses additional fluids that need to be replenished.

You’re pregnant or breast-feeding. The Institute of Medicine recommends pregnant women drink nearly 10 cups of fluids a day, and breast-feeding mothers get 13 cups of fluids daily.


An intense workout is another reason to consume extra water.

Include that cold beer on a hot day, but beware: Alcohol is also a diuretic, and drinking too much may leave you feeling thirsty, not quenched.

For easy workouts, replenishing with plain water is fine.

But for intensive workouts – such as training for a marathon – consider a sports drink.

That’s because when you sweat, you use electrolytes, salts and minerals that conduct electrical impulses in the body.

Sports drinks are made to replace those losses.

In fact, a 2010 New Zealand study showed that sports drinks taste better the more unbalanced your electrolyte levels get.

“You would need very intense exercise that uses enough of your electrolytes [to] need a sports drink,” Rolls says. “If running a marathon, it doesn’t hurt.”

For those who don’t run marathons, sports drinks will do no harm, but water is still better, Rolls says.

Don’t get over-hydrated
Drinking more fluids than your body can handle decreases levels of sodium, which is key in maintaining blood pressure.

It may lead to a rare life-threatening condition called hyponatremia that often causes nausea, vomiting, confusion and loss of consciousness.

“Over-hydration can cause cramps, headaches, weakness – even epileptic seizures when sodium is excessively diluted,” says François Lette, M.D., a physician in Executive and International Medicine at Mayo Clinic’s Florida campus.

Fortunately, when we overconsume water our bodies have a built-in coping mechanism.

When blood sodium levels drop, “our thirst shuts off, we stop drinking and our kidneys turn on to excrete the excess water as urine,” Murray says.

Still, why do some people drink more water when they’re not thirsty?

It may be habit, Rolls says. “You can get conditioned to need it.”

Source: Lifescript