You Ask, I Answer: Water

When did [the "8 glasses of water a day" myth] get started and how? Seems like for the past 7 years, [my] friends started talking about it.

But, just before that, bottled water became a trend to carry around. Please tell me it wasn't the bottle water companies who started this! You're suggesting, "drink water when you're thirsty" sounds unique, but hey, that's how I grew up.

-- "R from Ohio" (via the blog)

Dr. Heinz Valtin of Dartmouth's Medical School -- a kidney and water balance expert -- had that same question back in 2002 and decided to do a little investigating.

His conclusion? You can partially blame the Food and Nutrition Board of the National Research Council for starting this trend.

In a report, they recommended people take in a milliliter of water per calorie of food. If we apply that to a daily intake of 2,000 calories a day, we get two liters (or eight eight-ounce glasses) of water.

Why just partial blame? Well, that same recommendation also read, "most of this quantitiy is contained in prepared foods."

Pardon the cliche, but blame the media for spreading incorrect information. The water bottle, companies, of course, remained mum on the gaffe. Thus, here we are in the era of Vitamin/Smart/Protein water (some of which have almost as much sugar as a can of soda!)

This is not to say you shouldn't drink water. However, it should be a matter of drinking when you are thirsty (whether that adds up to four or nine glasses a day), not "because it's good for you."

You Ask, I Answer: Water/Dehydration

Sometimes I'm really thirsty in the summer and feel weak from the heat. What's the story on fitness waters and flavored sports drinks?

-- Antoinette Moore
Austin, TX

Good, plain old water is undoubtedly the most important nutrient. Not only is 65% of our body made up of it, we also need it to regulate bloodflow and keep all systems and internal organs running smoothly.

Dehydration is the direct result of fluid loss, which mainly occurs through urination and sweat (which is why our dehydration risk increases as temperatures rise).

One good way to tell if you are dehydrated is by looking at your urine. If it is a very dark, yellow color – and if your urine output is very low – you may be at risk for dehydration.

As far as fitness waters and flavored sports drinks go, please read the following posts to see what I think of Gatorade and Propel Fitness Water.

Vitamin Water, as healthy as it sounds, has as much sugar as soda. In my mind, it should be viewed as popping a vitamin and downing it with a soft drink.

In short, nothing beats water for combating thirst.

That being said, you should only drink water when you feel thirsty. Chugging down bottle upon bottle of water because “you have to” will do nothing but place unnecessary stress on your kidneys and bladder.

The often-quoted recommendation of eight glasses of water a day is the misinterpretation of a report that recommended said amount of total liquid (including that found in our foods as well as drinks other than water) daily.

If, however, your only sources of fluids are coffee and soda, I would encourage you to add in a two or three glasses of water to your day.