Eight glasses of water a day excessive for most people, study suggests | Hacker News Reader

Eight glasses of water a day excessive for most people, study suggests

theguardian.com

24 pointsmr_toad45 comments

>Many people only require about 1.5 to 1.8 litres a day, lower than the two litres typically recommended, the research suggests.

Of all the overzealous health advice we give this one seems pretty minor. The article is saying that we "require" six glasses. The article also says there is no downside to your health for drinking more.

> The article also says there is no downside to your health for drinking more.

You can poison yourself by drinking too much water. Can happen amongst very fit people doing a lot of exercise who think this means they have to down 10 litres of water in half an hour.

I don't know how anyone can do this without feeling intensely ill. I drank a gallon in about 40 minutes once, and it was readily apparent that nothing about it could be healthy, pleasant, or in almost any way a good idea.

I think they build up to it over time, all trying to out drink each other. I’ve seen mild cases in people in practice - people told to just sip a bit of water but they go ahead and drink multiple gallon jug fulls and then wonder why their legs stop working.

10 litres was an exaggeration of course. I think like 6 or something in a couple of hours is dangerous from the doctors I worked with?

This is from a group of fitness obsessed people doing very arduous exercise.

It's a common problem at large trail races. Enough so that it's one of the two things usually explicitly called out in the race briefings (the other is a reminder to not take ibuprofen).

Why no ibuprofen? I’m not a distance runner so I wouldn’t know.

What’s the problem with ibuprofen?

Ulcers, heart-attacks, kidney damage. But also they mask pain via reducing inflammation and the point of pain is to let you know something is wrong.

Like water it’s fine until you’re swallowing pill after pill.

>Ulcers, heart-attacks, kidney damage

Also, tendon injury/tendonitis seems linked to ibuprofen use. It may delay other kinds of healing (bone fractures, etc)

Not disagreeing with anything here, but are these specific to trail racing?

No, but if it's something that happens commonly in that context it makes sense to call out when in that context.

Yes. You can. But that is 5x the "eight glasses a day" rec.

I'd also wager the amount of people with health related issues due to too much water consumption is very little compared to too little water consumption.

Hyponatremia is indeed a risk for endurance athletes, and can occur even with drinking less than 10 liters of water. People have somehow got this idea that they need to be constantly drinking water during any exercise, but the reality is there is no health or performance impact to being a little dehydrated for a few hours.

https://www.nejm.org/doi/full/10.1056/nejmoa043901

https://wwnorton.com/books/Good-to-Go/

I just saw a study yesterday that concluded that this was the actual cause of Bruce Lee's death, I don't have the actual study now, but here's the first google link I found:

https://www.abc27.com/news/entertainment/doctors-believe-bru...

As I understand it, the advice is not meant to promote a specific amount of water (what unit of measurement is a "glass"?), but that one should drink water consistently throughout the day, as in a glass of water every couple hours that you're awake.

1 glass = 200ml 8 glasses = 1.6 metric liters

Not to be confused with imperial litres.

A bit tangential but..

A couple of years ago, I researched and wrote up an article on the effects of drinking additional water and weight loss. I was just curious because I was dieting and consistently read advice to drink lots of water to help aid dieting.

tldr: "thermogenic" (calorie-burning) effects of additional water intake are mostly negligible and based on old, non-replicated research. There may be very modest benefits for obese people during dieting, but the research is unclear. No other clear benefits that have a solid backing of research (that I could find).

https://ericra.com/writing/water_energy.html

I feel like drinking more water will make you feel more full which will cause you to consume more calories.

I believe 8 glasses came from a study that said we need approx. 8 glasses of water per day from all source, e.g. including food. But media outlets spread this as we should drink 8 glasses day and it stuck ever since.

8 glasses advice is sensible if you weren't also consuming liquid in other form (such as food, etc). If you are, then 8 might end up being too much. Think: soup/stew, cereal, certain forms of salad, yogurt, ice cream and so on. All contain water.

If your pee is clear, then you're probably hydrated just fine.

That's a myth. Unless it's really dark, urine color is not a useful indicator of hydration state.

https://pubmed.ncbi.nlm.nih.gov/10230169/

There's no sense in any particular quantity. If you're thirsty then drink some water. That's it.

My reasoning is simple: Do you believe humans have been drinking 2-3 liters per day historically? If you don't think so, why are you drinking as much today?! Unless you have some condition, don't drink water when you're not thirsty!

People tend to have a really strong reaction if you tell them they only need to drink when they're thirsty. I've stopped bringing it up in public since it's such a divisive topic.

Maybe if you tell them, "Well, then go to the bathroom every 30 minutes - it's healthier for you." then they will get the simple wisdom that we've survived so far following our internal signaling about our needs.

yeah outside of meat, a lot of what we eat is like 50-70% water as well. Most people get plenty of water. I guess I'm not an r/hydrohomies :) . I drink plenty between coffee, water, veggies, and occasional soda. I have had long arguments with people that while you will tend to pee a bit more with coffee/tea/soda, it's still a -net- source of water rather a dehydrator. It's a hard sell to people

Even cooked meat is something like 60% water (unless it's specifically dried out).

This is the naturalistic fallacy. Historically, people also lived in near starvation conditions, average lifespans were much shorter and a broken leg could be a death sentence.

If you apply the same logic to hunger, for example, even more people would be obese if they ate when they felt hungry, or if they followed their ancestors' instincts to gorge until full whenever the opportunity arose.

It's possible that we've historically survived in a local maxima of resource scarcity, and that "optimal" metabolic performance exists in a place beyond that, where resources are less scarce.

This is the fallacy fallacy.

How does infant mortality help us to reason that we should drink beyond thirst?

It would be the fallacy fallacy if I thought they were wrong, but I don't think they are. I think their reasoning behind their conclusion isn't completely sound, though.

It's not a fallacy. There is no proven health benefit to drinking water beyond your level of thirst.

I typically tell people like nikolai that they should also never eat fruit in winter because historically people didn't if it doesn't naturally grow where you live. After all, if we are imitating history then seasonal scurvy is a must (also seeing your teeth fall out will quickly cure you of this worldview).

People used to eat fruit during the winter - in the form of jams and dried or preserved fruit. Also, sauerkraut was an effective way to prevent scurvy.

Thirst is "drop everything and drink or you'll die soon", not "it would be good for you will being to have some water". In modern world with various soft drinks and soups you can drink no water at all and not feel thirsty once. See the problem?

It’s really not. Almost everybody is a couple of days away from serious dehydration health risks. You are not near death every time you’re thirsty.

I've been doing 3-day dry fasts for over 5 years and I'm fine. It was a bit harsh when I tried a 5-day one though.

You are missing the point. A modern human may not drink water for weeks and not want water. (First hand I went through coffee/alcohol/soft drinks periods at the uni, I know I'm not the only one.) It is objectively bad long term. The way out of this is to drink water, not to wait for thirst to start.

Thirst is an emergency signal not a useful metric to depend on planning water intake.

That is misinformation. There is no proven medical or performance benefit to drinking water when you're not thirsty. Where are you getting this ridiculous "emergency signal" nonsense?

https://wwnorton.com/books/Good-to-Go/

"Do you believe humans have been drinking 2-3 liters per day historically?"

Why not? Humans generally avoided arid climates until fairly recently, so I wouldn't consider the idea of drinking 2 liters per day as absurd on its face.

Also, one of our killer features is the ability to cool our bodies down by sweating. That makes us incredible endurance hunters, who can eventually exhaust even much larger and faster prey by simply following it around until it collapses from excess heat. But that requires drinking water.

So, hunters carried 2-3 liters of water during hunting? Have you seen in the museums the water pouches made from leather? They barely hold a liter to a liter and a half. Even the ones I've seen made from wood barely hold more than a liter. I doubt people always hunted close to streams so that they didn't need to carry water with them.

"They barely hold a liter to a liter and a half."

Depending on where you live, you will sweat out a lot more water on a daylong hunt.

But in semi-arid climates, where streams are rare, animals tend to gather around watering holes, so that might actually be the best place to start your hunt.

Drink water until your pee is mostly clear. Any exact X amount of recommendation is inaccurate because diets vary in the water content of your food and other drinks.

That's a myth. Unless it's really dark, urine color is not a useful indicator of hydration state. There is no reliable clinical evidence that having mostly clear urine produces better health outcomes.

https://pubmed.ncbi.nlm.nih.gov/10230169/

„Adam Ruins Everything” did a video on this:

https://youtube.com/watch?v=FwdqFHBaPwY

TL;DW: marketing by drink producers invented a problem to sell people who pursue healthy habits bottled water.

Not to mention corporations getting state permits to emptying reservoirs for free.

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