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Water Water Everywhere, How Much Should I Drink?

"For optimum health, everybody should drink eight glasses of water a day."

It's a number often repeated in articles, on TV and circulated worldwide via email. I hear it so often; I began to wonder where the recommendation originally came from. More importantly, I wanted to know how it applies to people working out. I started looking for an answer in 2003.

What is discovered is that the "eight glasses of water a day" suggestion isn't based on research. There's no single study that ever led to that recommendation. There's not even an agreement about where the idea originated or who said it first. I had been searching for an urban myth.

That doesn't mean drinking reasonable amounts of water is bad for you. In fact there are dozens of studies that have demonstrated increased fluid intake is beneficial for well-recognized disease states. It's also a widely documented fact that people who live in hot dry climates and people who exercise should drink more. It's even been documented that some diseases require fluid restrictions for optimum health.

But what I wanted to know is, how much water should the average person, and the average athlete drink every day?

In 2004 the Institute of Medicine of the National Academies (also called the IOM) released a report called, "Dietary Reference Intakes: Water, Potassium, Sodium, Chloride, and Sulfate." The IOM is the organization responsible for making recommendations on the quantity of nutrients Americans should be taking in daily. I figured they would give me the answer. Here's what they said.

"The vast majority of healthy people adequately meet their daily hydration needs by letting thirst be their guide. The report did not specify exact requirements for water, but set general recommendations for women at approximately 2.7 liters (91 ounces) of total water -- from all beverages and foods -- each day, and men an average of approximately 3.7 liters (125 ounces daily) of total water. The panel did not set an upper level for water."

That was it. Unfortunately it was a number I couldn't use. Since most people don't know how much water their food contains, there was no way to calculate how much water would still be needed. It was a dead end.

I put my search on hold until March of 2006 when The American Journal of Clinical Nutrition released a report called, "A new proposed guidance system for beverage consumption in the United States." They looked at combinations of all the typical things Americans were drinking and they attempted to calculate how much fluid would be appropriate for each individual.

The study came through with a few recommendations. One was that Alcohol consumption should be limited to, "no more than one drink for women and 2 for men (daily)." They also said that sports drinks should be, "consumed sparingly, except by endurance athletes because these beverages provide calories."

What did they say about water?

"It is not possible to define a set amount of water for each person because the water needs depend partially on overall diet and the water contained in the foods."

It was another dead end.

Finally, in March of 2008 Doctors Dan Negoianu and Stanley Goldfarb released a report titled "Just Add Water" where they looked into the eight glasses a day idea along with several others floating around the internet. What did they conclude?

"There is no clear evidence of benefit from drinking increased amounts of water. Although we wish we could demolish all of the urban myths found on the Internet regarding the benefits of supplemental water ingestion, we concede there is also no clear evidence of lack of benefit. In fact, there is simply a lack of evidence in general."

Dr. Goldfarb said, "A little mild dehydration for the most part is OK, and a little mild water excess for the most part is OK. It's the extremes that one needs to avoid..."

That was the answer. Unless you're drinking a prescribed amount of fluids under doctor's orders, you should let your thirst be your guide. If you're thirsty, drink more. When you're not, stop. It's just that simple.


Just Add Water also looked at what Dr. Goldfarb and Dr. Negoianu called the "four major myths" surrounding water consumption. This is what they concluded about three of the myths and what research has found out about the fourth.

Drinking More Water Helps Speed Toxins Out of the Body - NO

"The kidneys clear toxins. This is what the kidneys do. They do it very effectively. And they do it independently of how much water you take in. When you take in a lot of water, all you do is put out more urine but not more toxins in the urine,"

-Dr. Goldfarb


Drinking More Water Improves Skin Tone - NO

"Although frank dehydration can obviously decrease skin turgor, it is not clear what benefit drinking extra water has for skin... We were unable to find any other data regarding the impact of water intake on skin in otherwise healthy people."

-From the report, "Just Add Water"


Drinking Water Wards off Headaches - MAYBE

"To our knowledge, only one trial has examined headache prevention by increasing water intake. Fifteen patients with migraine headaches were randomly assigned to increased water intake or placebo for 12 wk. The number of hours of headache was quantified over 14-d intervals at the beginning and at the end of the trial. Although the treatment group had 21 fewer hours of headache compared with the control group, this difference did not reach statistical significance (the number of patients was obviously quite small). Given the economic impact of migraine on time lost from work, this area would seem to be ripe for further study."

-From the report, "Just Add Water"



Drinking Water Helps With Weight Loss - YES if you're over 35

There has long been speculation that drinking water before a meal would help with weight loss. Now studies show it's true, but it doesn't work for everybody. In a 2010 report released by Virginia Tech, they found that subjects who drank 16 ounces of water (about two cups) before every meal, lost more weight than people who didn't drink water before eating.

The study was small, (only 48 people) but it confirmed similar studies done at Virginia Polytechnic Institute in 2007 and one done at Virginia Tech in 2008.

Over the course of the three-month study the water drinkers lost an average of 15.5 pounds compared with a loss of 11 pounds for the control group. After a year the water drinkers lost even more weight for a year-end total of 17 pounds weight loss. Meanwhile the non-water drinkers gained weight and ended the year with an average of only 9 pounds weight loss.

But there's a catch. It didn't work for people who were under the age of 35. It takes longer for the stomach of an older person to empty, so researchers think the water made them feel fuller and less hungry. In younger people the water leaves the stomach much quicker and may not provide the same feeling of fullness.

If you're trying to lose weight, are over the age of 35 and aren't on a fluid restriction, start drinking two 8-oz. glasses of water before each meal.


Camelbak Hydration Calculator

There's a great hydration calculator created by camelbak products. It gives you an idea of how much water you'll need when engaging in various sports activities. Click Here for the Hydration Calculator.

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8/24/2008
Updated 2/17/2011
Updated 8/3/2016
Updated 3/7//2017