How Much Water Do I Need to Drink? What the Experts Say.

"Studies have produced varying recommendations over the years, but in truth, your water needs depend on many factors, including your health, how active you are and where you live."

  -Mayo Clinic Staff, April 19, 2008-



The whole controversy surrounding whether or not we really need to drink 8 X 8 ounce glasses of water a day started up all over again in April, when Drs. Negoianu and Goldfarb published their recent editorial, "Just Add Water" in the Journal of the American Society of Nephrology. They really hoped to debunk what they consider "the urban legend" of drinking 8 glasses of water a day.

 Back in 2002 Dr. Valtin of Dartmouth was the first one to try to figure out where this whole notion of drinking 8 glasses a day got started, and whether there was any truth to it. 

Now all of a sudden the press is saying "Forget about forcing down those 8 glasses of 8!"  I decided to read the studies myself and separate the truth from the fiction.  I also know how I feel when I drink my usual 64 ounces (8 glasses) of water (& other fluids) a day, and when I don't.  For me, it's all about "evidence-based living"!  Last weekend in Chicago, I didn't lug around my "stainless steel" water bottle, or down nearly enough liquid to fill my usual quota.  And yes, my body noticed it.  Won't do that again!  Needless to say, my trips to the bathroom were not what they should have been.  And as Dr. Goldfarb would say, "There was definitely less turgor in my skin."  (I looked wrinkled.)  As far as I'm concerned, water works!  I look better, my digestion is better, I feel better & even think better. You can decide for yourself, but here's what I learned about water.

What Drs. Goldfarb & Negoianu have to say:

• If you're healthy, live in a temperate climate and aren't exercising, just drink when you're thirsty.
• The notion of drinking extra water to remove toxins from your body is misguided.  In fact, if you drink too much water, you will decrease your kidney's filtration function.
• Increased water will improve the clearance of sodium, and since sodium-retention adversely affects blood pressure, this may be a benefit of drinking extra water.
• If water is supposed to improve the function of our body's organs, it must be retained in the body. Drs. G & N argue that water retention is just too variable, based on how quickly you are drinking.  A glass downed in 15 minutes will be excreted.  A glass downed over 2 1/2 hours will be retained. Women retain more water than men. Water mixed with easily-absorbed sugar is quickly excreted. My conclusion:  drink your water slowly and avoid sugary drinks!
• Drinking water before a meal will fill you up more than drinking after a meal. Eating foods containing water, e.g. soup, will fill you up & decrease your caloric intake more than just drinking a glass of water with a meal.  (see Barbarba Rolls, Volumetrics) And drinking water also increases the body's "calorie burn", aka "thermogenesis". 
• More research is needed to prove that drinking water will help us lose weight, and Drs. G & N think there's definite value in doing more research in this area.
• Decreased fluid intake has been associated with coronary disease, bladder cancer, urinary tract infections, colon cancer and kidney stones.  One trial even showed the possibility that increased water consumption might prevent migraine headaches. Drs. G & N recommend further study, but suggest that "Given that water cannot be patented, such trials seem unlikely."
• 2 cups of water increases the capillary blood flow to the skin, but  Drs. G & N aren't quite sure that this proves that water improves our skin tone.
• Drs. G & N's conclusion:  "Although we wish we could demolish all of the urban myths...regarding the benefits of supplemental water ingestion, we concede there is also no clear evidence of lack of benefit."  

What the Mayo Clinic and the Cleveland Clinic advise:

• According to Cleveland Clinic nutritionist Andrea Dunn, "Almost every cell in your body needs water to function properly.  Many of the patients I see don't drink enough water.  They aren't dehydrated, but they aren't drinking as much water as they should--especially considering how much your body needs."
• How much water do we "use up" every day?  Urine output=6 cups;  Sweat-bowel movements-breathing=almost 4 cups
• The body is between 55-75% water. More muscle=more water content.
• What if I don't drink enough water?  If you lose 10% of your weight in fluids you're dehydrated; but losing as little as 2% will cause tiredness, dull your critical thinking skills, and adversely affect your athletic performance.  
  
• What's the benefit of drinking adequate water?  Drinking enough water will lessen your chances of getting kidney stones, urinary tract infections, keep your joints lubricated, prevent or lessen the severity of colds & flu and prevent constipation.  For your body to be in tip top working order your must replenish the water you lose daily.

• How much do I need to drink a day?  

1. Andrea Dunn of the Cleveland Clinic advises her patients to drink 8-10 cups of water a day, and says, "Those who do report that they generally feel better."
2. According to the Mayo Clinic there are 3 ways you can approach this:  a.) Replacement approach: food accounts for 20% of your fluid intake, so add an additional 8 cups of water or other beverages to replenish what you've lost.  b.) Follow the 8 X 8 rule (not supported by scientific evidence, they add) & drink 64 ounces of fluids a day.  According to Dr. Valtin's article published in the American Journal of Physiology, you can count coffee, tea & soft drinks into the total as long as they're not a major portion of your fluid intake  c.)  The Institute of Medicine advises men to consume about 13 cups of total beverages a day and women to consume about 9 cups of total beverages a day.

• Under what conditions do I need to increase the recommended amounts of water?

1. Exercise:  If you sweat you need extra water to compensate for the fluid loss.  Short bouts of exercise require 1.5-2.5  extra cups.  More intense workouts, lasting more than an hour require more.  Drink sports drinks with sodium during long bouts of intense exercise.
2. Environment:  Hot or humid weather, heated indoor air, high altitudes, airplane flights all require more fluids.
3. Illnesses or health conditions: Fever, vomiting, diarrhea, (may require oral rehydration solutions), bladder infections or kidney stones.
4. Pregnancy & breast-feeding:  The Institute of Medicine recommends pregnant women to drink 10 cups of fluids daily, and breast-feeding moms to drink 13 cups.

• Tips to improve hydration

1. Drink tap water over bottled water.  The EPA regulates tap water & requires it to be analyzed for chemicals & bacteria. The FDA regulates bottled water & doesn't require analysis for these substances. 
2. Cleveland Clinic: The best way to stay hydrated is to sip 1/2 cup of water each hour you're awake, .  Remember Drs. G & N's finding that water is retained if it's drunk slowly?
3. Mayo Clinic: Drink a glass of water with each meal & between each meal.
4. Don't drink sugary water/soft drinks.  The sugar causes the water to be excreted.
5. Juicy fruits & veggies help to keep you hydrated.
6. Hydrate before, during & after exercise.
7. Don't use thirst alone as a guide for when to drink.  You may already be slightly dehydrated by the time you feel thirsty.
8. The older you are the less able your body is to sense dehydration, and for your brain to send the "drink now signal". 
9. Although it's very uncommon, & mostly seen in endurance athletes, too much water can cause hyponatremia. The kidneys are overloaded & can't excrete the excess water, which dilutes the mineral content of the blood, resulting in low sodium levels. Again, this is extremely rare.

• How can I tell if I'm drinking enough?   Use the color test.  If your urine is clear or pale yellow you're getting enough.  If it's intense yellow (excluding B vitamin coloring) or gold, you need more water.

As far as I'm concerned, Drs. Negoianu and Goldfarb didn't  convince me to stop drinking 8 X 8 glasses of water.  The evidence in the literature may not be there, but as they say, there's no patent on water, and no incentive to prove how beneficial it is.  Water makes me feel better, there are no adverse effects, so I'm following the advice of the Cleveland Clinic, the Mayo Clinic and my body.  How much do you drink a day & do you feel differently when you drink more?