Mythbusting

[trixtah]

I've come across that old chestnut that averagely-active people "MUST drink 8 glasses of water a day" four times in the last week, in various formats. And I wish that people would stop spreading that idiocy around. Yes, we do need to consume about that much fluid in a day, but, surprise, surprise, we get at least half of it in our food. The component of that myth that I find particularly galling is that "when you're thirsty, you're already dehydrated". What crap. Thirst is how your body stops you from being dehydrated.

A well-publicised review was carried out a few years ago by Dr Heinz Valtin, who pretty much debunked all those myths after examining extant literature and studies. Here's the part about the "thirsty is too late" myth:

...a rise in plasma osmolality of less than 2% can elicit thirst, whereas most experts would define dehydration as beginning when a person has lost 3% or more of body weight, which translates into a rise in plasma osmolality of at least 5%.

Oh, and as for the rubbish that caffeinated drinks don't count for fluid intake because they act as diuretics? Well, they're not diuretic enough to totally purge you of all that liquid you just consumed, thus upping your total fluid intake. Alcohol, however, will dehydrate you. And if anyone has experienced a hangover, you know how different that feels compared to being a bit thirsty.

Snopes has a good rebuttal of that stupid "75% of Americans are chronically dehydrated" email that appears to be doing the rounds again. But the Valtin study is very readable as well, and good for more background.

Really, like anything else, it all comes down to listening to what your body is telling you. If you are thirsty, drink. Simple.

Comments

[trixtah.livejournal.com]

Oh, absolutely. I'm ranting about that kneejerk advice that's handed out to people who are never in non-temperate environments and who exercise by walking to the coke machine twice a day. I myself normally go through about 700ml of liquid in an hour's workout, which is the same as what I drink all day when I'm not exercising. And I sweat quite lightly.

I think sometimes people get used to ignoring their body's cues, and don't notice that they're getting thirsty. Hell, our bodies are all different and have different needs, which the "health" fascists often seem to forget. Frequently. (I should have appended my other rant that pure water is actually not terribly efficient for rehydration, but I'd best leave that for another time.) But I am totally of the view that people should learn what their own bodies need, rather than carrying out spurious advice by rote.

[damned-colonial.livejournal.com]

Yeah. That whole "listening to your body" thing is a weird one. Mine's incredibly communicative if I give it half a chance, but I get the impression this is not commonly the case. I hear lots of people can't even tell where they are in their menstrual cycle without counting. Wtf?

listening to your body

[saluqi.livejournal.com]

Giving your body a chance to communicate is such a loaded thing to do for many people, it doesn't surprise me that people lose the ability.

Sometimes it's trained out of you as well, especially if you're raised in a religious tradition that is big on the mind ruling the flesh. Hell, just being female is enough to get a dose of professionally authorised mind/body disconnect. Plenty of women get told by doctors that common menstrual ailments are all in their head. My sister went through a number of doctors basically telling her she was fat and lazy until her PCOS was diagnosed for example. Part of her believed it too, fortunately other part of her kept looking for a solution and eventually found it - tho' it took years.

I don't have any grand solutions to this, but if I had been told "listen to your body" as a 23 year old I would have nodded wisely and internally dismissed it. Partly because of my values, but also partly because I just didn't understand what it meant. It was martial arts training and bottoming that finally cracked open a few clues. Now of course, my problem is getting it to shut up ;-)