44 comments

[ 5.9 ms ] story [ 106 ms ] thread
Given how critical this is I suspect your body is better at it then you are...

I'd say "Drink when you are thirsty".

And when your pee is yellow / yellowish ...
And double check intake if you get a headache (typical symptom of dehydration).
I'm pretty sure yellow pee is normal. It's when it gets dark and turns towards brown that you have a problem.
Yes, yellow pee is normal. But it can also be an indicator that you have consumed less water. When we drink "adequate" water, our pee is less yellowish and can even be quite clear.
https://xkcd.com/1708/

I often heard really exaggerated advice about how much water to guzzle every day. It got crazy.

One day several years ago, a nurse was taking vitals on me and told me to drink, I don't know, 48 cups per day or something? It was huge. And I regarded her with incredulity. So upon being taken in to see the doctor, and this was a physician that I really trusted and had a good long tenure, I repeated the advice and I said, "That's BS, right?" and she said yep, and I'll talk to that nurse...

I am especially wary of my fluid intake because I live in an urban desert. Therefore I must constantly drink fluids when it's hot to stay healthy and hydrated. However, I must also gauge my ability to find a bathroom while out on the road, and when you ride the bus, good luck with that! It might be 3 hours, or you're forced to make a small order at a restaurant to become a customer. So it's really a delicate balancing act of how much to drink. And also, remembering to use the bathroom at every opportunity!

> One day several years ago, a nurse was taking vitals on me and told me to drink, I don't know, 48 cups per day or something? It was huge. And I regarded her with incredulity.

That sounds like enough water to actually be harmful/deadly, especially depending on what "cups" means there.

I wonder if that nurse was confusing "cups" with "ounces".
Or maybe “four to eight” cups. The idea of drinking almost 12 liters of water each day is pretty amusing.
Ha! would love to see that scene where the nurse gets shit from the doctor.
Y'all took me quite literally as I exaggerated for effect. I am merely a panel in that xkcd comic. Which hat I am wearing is left as an exercise for the reader.
Amusing and unrealistic if you consider our ancestors and cultures in hot and cold climates...

It makes me wonder how some people don't seem to recognize, that we as a species have been on this planet for quite some time now, and that IS the greater part of out existence on this planet when compared to how long we've studied science and medicine of today!

The timeline of either is heavily weighted on the side absent of anything we would call "modern." :-)

You know what even cooler than an online calculator? Your hypothalamus, kidneys and hormones that regulate water intake and excretion!
Converting the article's recommendations to metric, that's 1/32 of your body weight + 680g per hour of exercise + 680~907g depending on weight if you're pregnant or breastfeeding.
Drink when you're thirsty. Most anything above that is probably fine.
As we age our "thirst response" becomes less reliable. I really don't get thirsty until I am starting to become dehydrated. It's good to have a guideline to inform my self-imposed daily drinking regimen.(which I have a hard time keeping)
Also, I've found, temperature can have a huge influence. I like to do winter camping in the middle of nowhere in the mountains. I was surprised to discover that when I'm in freezing conditions like that, I simply won't feel thirsty -- apparently ever -- so I set a timer to remind me to drink.

I learned this the hard way on the third day of my first such trip, when my urine had become brown due to dehydration.

It is probably best to follow real information then.

Note that while your thirst response may be declining as you age, mine hasn't.

Annicdodes aren't data, mine or yours.

IMHO the 8x8 myth may or may not be optimal guidelines for you as they aren't based on anything but rumors.

It's not just aging that makes us bad at noticing when we're dehydrated. The ubiquity of so many types of foods has given us the ability to satisfy the craving for that which stimulates our senses, not necessarily what we need.

I know this is anecdotal, but I've heard so many people tell me that they skip meals because they simply "forgot to eat." Do you think those people remembered to drink water? I don't think so.

So, yes, people tend to be terrible at noticing what they need, and when they do notice they are terrible about doing something about it.

Looking at the folks around me, skipping an occasional meal seems like the least of our problems.
Drink when you haven't peed for a while or your last pee was yellow. This is actual advice given to athletes and it's pretty effective IMO.
This is not necessarily reliable when traveling to high altitude or in unusually hot conditions.
Which is both true, but also irrelevant for 99% of the people for 99% of the time.
I'm not drinking 4 Nalgene bottles of water a day. That's not going to happen.
Also, if you’re exercising a lot and/ or are otherwise heavily sweating, make sure to consume electrolytes. Hyponatremia is a thing.
There's no mention of the fact that the food we eat is also a significant source of water.

This is a common misunderstanding around those "you need X glasses of water per day" recommendations -- much (sometimes, most) of your needed water comes in your food and doesn't need to be consumed as a separate thing.

And even though there are other health considerations to them, water you take in the form of coffee, tea, soda, etc., also counts.

Isn't the 8x8 rule that they try to expand on firmly established to be pseudo scientific myth?

https://journals.physiology.org/doi/full/10.1152/ajpregu.003...

Woo + math == woo

I think the 64oz assumes you will get more from food and other beverages besides "water" and is probably plenty for an average person with an average level of activity.
Yes. There is no medical basis for any amount of water above "what you're thirsty for".

Our thirst system is as precise and robust regarding water as our pancreas is for glucose.

My pancreas doesn't tell me when I need more sugar.
I think they mean that your pancreas automatically spits out the right amount of insulin for the sugar in your bloodstream.
Someone always claims this.

If I only drink when I'm thirsty, then half the time I'll be depressed and headachey and unfocused and not thirsty until I idly grab a drink and suddenly find myself standing in front of the sink chugging three glasses of water.

If your thirst system is finely tuned, that's nice for you. I and millions of others could use a better system.

If your spit isn't wet like water, then you could do with a drink, although being in an anxious state may indicate a false positive.

Thirst is an early'ish warning, but not early enough if you've eaten food that needs more water in order for your body to process it than you have consumed prior to eating, or you have diarrhea, or you are low on electrolytes, or your kidneys have problems monitoring and maintaining the balance of said electrolytes.

See also:

https://pubmed.ncbi.nlm.nih.gov/31082167/

1ml per every kcal consumed.
IMO people way overthink this. The range of acceptable amount of water is large, you don't need a formula to calculate some exact amount per person.
After having a kidney stone removed I've implemented some simple rules: glass of water after waking up and before going to bed, glass of water with meals, drinking during physical activity and then during the day I monitor my urine color and drink a glass of water straight away when if it's dark.
I am surprised they don't mention salt.
You have a hyper-intelligent system that calculates how much you should drink, it's called thirst. Drink when you're thirsty, mostly water, end of story.