fasthands9 4 days ago

>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.

  • chrisseaton 4 days ago

    > 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.

    • tbihl 4 days ago

      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.

      • gregoryl 4 days ago

        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).

        • Our_Benefactors 4 days ago

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

        • plugin-baby 4 days ago

          What’s the problem with ibuprofen?

          • chrisseaton 4 days ago

            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.

            • plugin-baby 3 days ago

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

              • andreareina 3 days ago

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

            • joecool1029 3 days ago

              >Ulcers, heart-attacks, kidney damage

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

      • chrisseaton 4 days ago

        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.

    • nradov 3 days ago

      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/

    • fasthands9 4 days ago

      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.

zach_garwood 4 days ago

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.

unixhero 4 days ago

1 glass = 200ml 8 glasses = 1.6 metric liters

  • bradwood 3 days ago

    Not to be confused with imperial litres.

ericra 4 days ago

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

  • smabie 3 days ago

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

pleb_nz 3 days ago

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.

deafpolygon 3 days ago

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.

  • nradov 3 days ago

    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.

nikolay 4 days ago

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!

  • heavyset_go 3 days ago

    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.

    • throwaway290 3 days ago

      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).

      • nikolay 2 days ago

        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.

    • nradov 3 days ago

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

    • fullmoon 3 days ago

      This is the fallacy fallacy.

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

      • heavyset_go 2 days ago

        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.

  • inglor_cz 3 days ago

    "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.

    • nikolay 3 days ago

      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.

      • inglor_cz 3 days ago

        "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.

  • dorkwood 4 days ago

    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.

    • stjohnswarts 3 days ago

      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

      • nradov 3 days ago

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

    • nikolay 4 days ago

      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.

  • throwaway290 3 days ago

    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?

    • colechristensen 3 days ago

      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.

      • throwaway290 3 days ago

        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.

        • nradov 3 days ago

          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/

      • nikolay 3 days ago

        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.

reducesuffering 3 days ago

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.

  • nradov 3 days ago

    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/

Ralfp 4 days ago

„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.

  • egberts1 4 days ago

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