Why do our bodies not get thirsty enough to drink the “recommended” amount of water?


I keep seeing these things about how people should drink 2 liters a day or 3 liters or whatever but if i had to estimate i think i drink about 0.5 to 1 liter a day, i just drink when i feel thirsty and that’s the amount i need to drink in a day to not feel thirsty…

If we only eat when we’re hungry why do we have to drink when we’re not thirsty?

In: Biology


It’s actually a myth that we need 2 liters a day. A lot of studies that say we do need that much, were funded by bottled water manufacturers. There was a medical journal in 1945 that said we needed 2.5L, but it also rightfully pointed out we get most of that from food. Real answer is, your thirst is like your hunger – Drink when thirsty, eat when hungry

Assuming there’s no underlying disorders or health problems affecting a person’s eating/drinking habits, doing as the body wants isn’t a terrible idea.

However, 2L of water isn’t an unreasonable amount of fluids. I’d look at your urine color, for a more precise judgement. There’s plenty of resources out there to illustrate the exact shades you’re looking for.

And with all things health related, asking your doctor never hurts.

You’re not supposed to feel thirsty. You’re supposed to drink to avoid the feeling of thirst.

1) The recommendations are junk

2) The amount YOU require varies enormously from person to person.

3) The amount you require varies according to what you’ve been doing, sweating, local temperatures, time of day, how much you pee, etc.

4) You get an awful lot of water from food. A potato is something like 80% water. 20% solids.

5) Your body knows far better than any statistic what it needs, and will make you desire certain things. Of course, you have to moderate your bodies desires (like all such things) but if you’re thirsty, then drink and if you’re not you likely don’t need water.

Sometimes we confuse thirst with hunger. We think we’re hungry when we’re actually just dehydrated.

Also, you can ‘get used’ to the feeling of dehydration just because you don’t know what it’s like to be hydrated. i.e. chronic dehydration causes dry skin, sluggishness etc. but you might blame those problems on other factors. Point is that the symptoms of dehydration are more than just thirst.

We have three sensations related to thirst and hunger.

Dire thirst – really need water. Associated with dry mouth, chapped lips, dehydration, etc
Starvation – when hunger pangs turn into hunger stabbing
Hunger – day to day sensation that it’s time to eat. This feeling occurs when you need food or water.

So this is why it is advised to drink some water if you are hungry. The feeling may go away. Your body may be craving water, but there is no separate sensation for this.

You don’t have a drive to drink water because we are taught incorrectly how to listen to our bodies. It is there, but we typically just snack when hungry.

When you’re thirsty, you already started the dehydration process. You should be drinking before your body is thirsty.

A lot of people have explained it. To sum it up? Water bottle companies funded studies to “prove” we needed that much water. Your body knows best. Listen to it’s signs. As stated before. Eat when hungry. Drink when thirsty.

Those recommendations are based on total water consumption, not just drinking water. If your diet has other components than Jacob’s cream crackers, you are consuming significant amounts of water through the food you eat.



Well you do. The difference is that you get a lot of water from your food. The water requirement you mention is absolute and doesn’t care if the water comes from food or the tap. That said drinking more water than you need generally isn’t bad for you assuming you don’t way over do it so if you drink that much a day you should still be fine.

1) Are you getting the recommended amount of physical activity? Working up a regular sweat, getting in your 10,000 steps, are all going to take water.

2) Do you eat foods with fairly high water content? If your favourite foods are watermelon, soup, and grapes I’m betting you get a fair amount of water that way.

3) Do you live in the average climate? Perhaps you live somewhere cooler and damper where your body isn’t going to have as much water sucked out if it by the air.


You don’t have to drink when you are not thirsty. That’s a myth. Your body regulates it’s own water intake using thirst far better than you ever good.

It started with an estimate for the average amount needed by the average human adult. Notice I used words like average and estimate. The actual amount of water you need varies wildly from person to person and from day to day.

Drink when you are thirsty and you will get the right amount for your current needs. Only exception is when you consume a lot of something that messes with your water balance, such as alcohol.

We need approximately 30 ml per kg of body weight. For a 70 kg person, it is a little over 2 lts of water per day. But this doesn’t mean 2 liters of “pure” water.

Beverages like juice, milk, sodas, coffee, all have water. It is not the same as drinking only water, but still hidrates you. Coffee is a weak diuretic (actually a calciuric, meaning it makes you pee calcium among other minerals) but the effect is minimal so it still hydrates you. Alcohol on the other hand, it is a diuretic which can dehydrate you (and dehydration is one of the reasons you get a hangover).

Also the foods we eat have water, fruits and vegetables have lots of water and tgis hydrates you.

In some metabolic reactions in your body water is a byproduct, so this provides a small quantity of water for your body (but just water, not electrolytes).

So even if we need around 2 lts of water, we have many more resources besides a glass of water to get it, which is why your body isn’t thirsty all the time

Every time I drink the daily recommended water I pee every 10 minutes including the night, even if I stop drinking water a few hours before bed. I just drink when I feel like I need it lol

Bodies are weird. I drink almost a gallon of water per day, my bestie drinks maybe 1 can of soda per day and that sustains him.

Your body and your activities are the biggest factor.

When I spend time out in the desert, like Utah red-rock regions, Arches, and similar, I completely finish two full gallons during the day (8 liters for the rest of the world). I usually drink even more after getting back to camp, or the motel. I insist that my family carries at least a full gallon per person, with more in the vehicle for refills.

On the opposite end of the spectrum… If your day is spent sitting in front of the computer all waking hours, in a temperature controlled, humidity controlled apartment with no notable exercise, you will need much less water.

If you get out and exercise, or do strenuous work, or even tasks like gardening, you can lose a lot of water.

Your mileage may vary.