Myths and Facts About Hydration Requirements
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Sarauk2sf
Posts: 28,072 Member
Obviously, water is not a myth, but there are two main myths or misconceptions that abound: 1) you need at least eight glasses of water a day, and 2) only water hydrates you.
1) You need at least eight glasses of water a day
Proper hydration is required to flush toxins from vital organs, carry nutrients to your cells and a host of other things. However, the question is, how much do we need? The ‘eight glasses a day’ is a recommendation that is seen a lot, including here.
It is not completely clear where the 8 glasses a day came from, but there is no evidence to support the requirement.
Heinz Valtin did an extensive review of this recommendation, which was published in the American Journal of Physiology (http://ajpregu.physiology.org/content/283/5/R993.long). He concluded that there is lack of any evidence supporting the eight glasses a day. “I have found no scientific proof that we must “drink at least eight glasses of water a day,” nor proof, it must be admitted, that drinking less does absolutely no harm. However, the published data available to date strongly suggest that, with the exception of some diseases and special circumstances, such as strenuous physical activity, long airplane flights, and climate, we probably are currently drinking enough and possibly even more than enough.”
In fact, in extreme circumstance, drinking excessive amounts of water can actually be dangerous, resulting in hyponatraemia (water intoxication).
So how much water, or other fluids, should you drink a day? That depends on your personal circumstances including how active you are, climate, how much fluid you get from your diet and your general health. The following is a quote from the Mayo Clinic: “Generally if you drink enough fluid so that you rarely feel thirsty and produce 1.5 liters (6.3 cups) or more of colorless or light yellow urine a day, your fluid intake is probably adequate. If you're concerned about your fluid intake or have health issues, check with your doctor or a registered dietitian. He or she can help you determine the amount of water that's right for you.”
2) Only water hydrates you
The simple answer is that you can obtain fluids for hydration from beverages and food. It is not just plain water that hydrates you and caffeine is basically no more a diuretic than water is unless consumed in large quantities, and even then, the diuretic effect is minimal. You do obviously have to count the calories in your beverages/food.
For the geeks, or if you do not believe me:
http://www.mayoclinic.com/health/water/NU00283 - any beverage counts
"beverages such as milk and juice are composed mostly of water. Even beer, wine and caffeinated beverages — such as coffee, tea or soda — can contribute"
"What you eat also provides a significant portion of your fluid needs. On average, food provides about 20 percent of total water intake."
http://www.jacn.org/content/22/2/165.short flavored plain water counts
"Inclusion of plain drinking water compared to exclusion of plain drinking water in the diet did not affect the markers of hydration used in this study."
http://www.jacn.org/content/19/5/591.short any beverage counts
"This preliminary study found no significant differences in the effect of various combinations of beverages on hydration status of healthy adult males. Advising people to disregard caffeinated beverages as part of the daily fluid intake is not substantiated by the results of this study."
http://bjsportmed.com/content/40/5/406.abstract sports drinks can hydrate more than plain water in some situations
"Ad libitum consumption of a CHO-E drink may be more effective than water in minimising fluid deficits and mean core temperature responses during tennis and other similar training in adolescent athletes."
http://www.jacn.org/content/26/suppl_5/592S.short food counts
"Various reports indicate that humans receive 20–25% of their daily water intake from food. Fruits, vegetables and other high-moisture foods, therefore, make an important contribution to total fluid intake."
http://europepmc.org/abstract/MED/12834577 the diuretic effect of caffeine is minimal
"...nor does it cause significant dehydration or electrolyte imbalance during exercise."
http://europepmc.org/abstract/MED/12187618 the diuretic effect of caffeine is minimal
"The literature indicates that caffeine consumption stimulates a mild diuresis similar to water, but there is no evidence of a fluid-electrolyte imbalance that is detrimental to exercise performance or health"
"Investigations comparing caffeine (100-680 mg) to water or placebo seldom found a statistical difference in urine volume."
http://jap.physiology.org/content/83/4/1152.abstract? interesting one about alcohol post exercise and recovery
“There appears to be no difference in recovery from dehydration whether the rehydration beverage is alcohol free or contains up to 2% alcohol, but drinks containing 4% alcohol tend to delay the recovery process.”
In the interest of clarity, this post is not intended to encourage people not to drink water – it has zero calories and is free/cheap, but to try to clear up any misunderstandings with regard to hydration.
1) You need at least eight glasses of water a day
Proper hydration is required to flush toxins from vital organs, carry nutrients to your cells and a host of other things. However, the question is, how much do we need? The ‘eight glasses a day’ is a recommendation that is seen a lot, including here.
It is not completely clear where the 8 glasses a day came from, but there is no evidence to support the requirement.
Heinz Valtin did an extensive review of this recommendation, which was published in the American Journal of Physiology (http://ajpregu.physiology.org/content/283/5/R993.long). He concluded that there is lack of any evidence supporting the eight glasses a day. “I have found no scientific proof that we must “drink at least eight glasses of water a day,” nor proof, it must be admitted, that drinking less does absolutely no harm. However, the published data available to date strongly suggest that, with the exception of some diseases and special circumstances, such as strenuous physical activity, long airplane flights, and climate, we probably are currently drinking enough and possibly even more than enough.”
In fact, in extreme circumstance, drinking excessive amounts of water can actually be dangerous, resulting in hyponatraemia (water intoxication).
So how much water, or other fluids, should you drink a day? That depends on your personal circumstances including how active you are, climate, how much fluid you get from your diet and your general health. The following is a quote from the Mayo Clinic: “Generally if you drink enough fluid so that you rarely feel thirsty and produce 1.5 liters (6.3 cups) or more of colorless or light yellow urine a day, your fluid intake is probably adequate. If you're concerned about your fluid intake or have health issues, check with your doctor or a registered dietitian. He or she can help you determine the amount of water that's right for you.”
2) Only water hydrates you
The simple answer is that you can obtain fluids for hydration from beverages and food. It is not just plain water that hydrates you and caffeine is basically no more a diuretic than water is unless consumed in large quantities, and even then, the diuretic effect is minimal. You do obviously have to count the calories in your beverages/food.
For the geeks, or if you do not believe me:
http://www.mayoclinic.com/health/water/NU00283 - any beverage counts
"beverages such as milk and juice are composed mostly of water. Even beer, wine and caffeinated beverages — such as coffee, tea or soda — can contribute"
"What you eat also provides a significant portion of your fluid needs. On average, food provides about 20 percent of total water intake."
http://www.jacn.org/content/22/2/165.short flavored plain water counts
"Inclusion of plain drinking water compared to exclusion of plain drinking water in the diet did not affect the markers of hydration used in this study."
http://www.jacn.org/content/19/5/591.short any beverage counts
"This preliminary study found no significant differences in the effect of various combinations of beverages on hydration status of healthy adult males. Advising people to disregard caffeinated beverages as part of the daily fluid intake is not substantiated by the results of this study."
http://bjsportmed.com/content/40/5/406.abstract sports drinks can hydrate more than plain water in some situations
"Ad libitum consumption of a CHO-E drink may be more effective than water in minimising fluid deficits and mean core temperature responses during tennis and other similar training in adolescent athletes."
http://www.jacn.org/content/26/suppl_5/592S.short food counts
"Various reports indicate that humans receive 20–25% of their daily water intake from food. Fruits, vegetables and other high-moisture foods, therefore, make an important contribution to total fluid intake."
http://europepmc.org/abstract/MED/12834577 the diuretic effect of caffeine is minimal
"...nor does it cause significant dehydration or electrolyte imbalance during exercise."
http://europepmc.org/abstract/MED/12187618 the diuretic effect of caffeine is minimal
"The literature indicates that caffeine consumption stimulates a mild diuresis similar to water, but there is no evidence of a fluid-electrolyte imbalance that is detrimental to exercise performance or health"
"Investigations comparing caffeine (100-680 mg) to water or placebo seldom found a statistical difference in urine volume."
http://jap.physiology.org/content/83/4/1152.abstract? interesting one about alcohol post exercise and recovery
“There appears to be no difference in recovery from dehydration whether the rehydration beverage is alcohol free or contains up to 2% alcohol, but drinks containing 4% alcohol tend to delay the recovery process.”
In the interest of clarity, this post is not intended to encourage people not to drink water – it has zero calories and is free/cheap, but to try to clear up any misunderstandings with regard to hydration.
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Replies
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You had me at "beer"!
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You had me at "beer"!
and also with you:drinker:0 -
Next round's on me!0
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:drinker: :drinker: :drinker:0
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Wonderful, wonderful!!0
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I saw a new one in my newsfeed recently: you have to drink a certain amount of water to lose weight, and many failing to lose weight just aren't drinking enough.
And she called me ignorant for not believing such complete tosh.:huh:0 -
Excellent post.0
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Great post! This is why I quit logging water a long time ago. :drinker:0
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It takes 8 liters [of water] to make one liter of beer. So for every liter of beer I drink I log 8.
Done!
Edit: of water.1 -
I only have anecdotal evidence to support this, but every day after I drink my morning coffee I have to poo. So I say it's a diuretic.1
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You're a fcking genius!It takes 8 liters [of water] to make one liter of beer. So for every liter of beer I drink I log 8.
Done!
Edit: of water.0 -
I only have anecdotal evidence to support this, but every day after I drink my morning coffee I have to poo. So I say it's a diuretic.
A diuretic is about pee not poo.
Also, if you look at all the peer reviewed studies I provided, it is not. It is a stimulant however.
Sorry - but I just had to add this:
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I only have anecdotal evidence to support this, but every day after I drink my morning coffee I have to poo. So I say it's a diuretic.
A diuretic is about pee not poo.
Also, if you look at all the peer reviewed studies I provided, it is not. It is a stimulant however.
Sorry - but I just had to add this:
Perfect!! If your lyin' your dyin'!! love it.0 -
YAY!!!!! Coffee drinkers unite!!!!0
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I saw the reference to where the 8 glasses, or 64 oz's of water came from.
http://www.scientificamerican.com/article.cfm?id=eight-glasses-water-per-day
In 1945 the Food and Nutrition Board, now part of the National Academy of Sciences's Institute of Medicine, suggested that a person consume one milliliter of water (about one fifth of a teaspoon) for each calorie of food. The math is pretty simple: A daily diet of around 1,900 calories would dictate the consumption of 1,900 milliliters of water, an amount remarkably close to 64 ounces. But many dieticians and other people failed to notice a critical point: namely, that much of the daily need for water could be met by the water content found in food.0 -
I saw the reference to where the 8 glasses, or 64 oz's of water came from.
http://www.scientificamerican.com/article.cfm?id=eight-glasses-water-per-day
In 1945 the Food and Nutrition Board, now part of the National Academy of Sciences's Institute of Medicine, suggested that a person consume one milliliter of water (about one fifth of a teaspoon) for each calorie of food. The math is pretty simple: A daily diet of around 1,900 calories would dictate the consumption of 1,900 milliliters of water, an amount remarkably close to 64 ounces. But many dieticians and other people failed to notice a critical point: namely, that much of the daily need for water could be met by the water content found in food.
Yes - that was concluded in the study I linked by Heinz Valtin as the most likely, but misinterpreted source of the 8 glasses myth.0 -
A recent article I read by another psychologist indicated that the recommendation was from a panel regarding space travel very early on (if I recall correctly, ca 1950's); apparently, they surmised that a human would need 8 cups of water per day in space. And here we are... LOL. If you are interested in the link, message me and I will locate it.0
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A recent article I read by another psychologist indicated that the recommendation was from a panel regarding space travel very early on (if I recall correctly, ca 1950's); apparently, they surmised that a human would need 8 cups of water per day in space. And here we are... LOL. If you are interested in the link, message me and I will locate it.
Could be another reason the myth came about..I had not heard of that one.0 -
It takes 8 liters [of water] to make one liter of beer. So for every liter of beer I drink I log 8.
Done!
Edit: of water.
Yes, but only because of water that evaporates during boiling and that taken to grow and malt the grain... :laugh:0 -
I've always thought the 8 glasses wasn't accurate. I always thought though, that it was half your body weight in water. But lately I've been aiming for clear toilet bowls, and have gotten them. 0
