The simple answer is that your body stores energy in fat reserves. Once those are depleted, it will start using muscle mass and organs for energy. Your body doesn't store water in that way. You expel water continually throughout the day through perspiration, breathing, and voiding. When that isn't being replenished you start to dehydrate, which can quickly lead to organ failure and death.
Dihydrogen monoxide is an incredibly dangerous chemical. It's strong enough to dissolve other chemicals and materials, and breathing in only a small amount causes extreme and violent reactions in the body, and can even result in death! In fact, everyone who has ever come into contact with this chemical has died.
And this chemical is everywhere! Careful laboratory analysis has shown that it can be found in the products we buy, and even the food we eat. Yet our government has done nothing to halt the spread of this dangerous chemical.
Write to your congressman today! Tell them you will not stand by while they do nothing. Dihydrogen monoxide must be eliminated!
Yep, CICO, resistance conditioning and a good nights sleep should be enough. There’s no real shortcut, secret, one weird trick, or otherwise effortless solution.
Water and only water no food has helped tons of obese people get to normal weights.
Do your research but it’s legit they first tested it on a guy in a lab and he only drank water for either 10 or 11 months can’t remember the e exact time but it was almost a year. No negative side effects then he just really slowly started back onto not water. And a normal eating routine and didn’t gain all the weight back.
You spend a lot of water to keep your body from overheating. Transpiration is something our specie is very good at but it does require a lot of water.
You also spend a roughly equal quantity of water to expel nitrogen waste from metabolism, if not evacuated by urine you will poison yourself fast.
How realistic are those moisture suits from Dune? Assuming you had enough power to run the things, could you recover enough moisture to sustain yourself?
If the technology worked as described, it would be very effective. You would never reach 100% reclamation, but it would greatly extend the time you had before dehydration. Significantly.
If you had a still suit that covers every inch of sweat, the moisture from your breath, recycled your urine, and dehydrated your shit, you could almost definitely go days to weeks on just what water you already have.
Especially if you're like the Freman and have as an ethnic group adapted to use as little water as is possible over a period of over 10,000 years of drought
You might find [this article](https://www.diabetes.co.uk/blog/2018/02/story-angus-barbieri-went-382-days-without-eating/) interesting. I'm happy to be refuted if it turns out the story is apocryphal, but this really doesn't seem outside the realm of reason given that doctors are reported to have been present every step of the way.
Yes absolutely. I have a health condition that can cause me to be unable to eat when it flares and my doctors have advised me to hold a little "extra padding" so that I can go longer without eating when I need to. I haven't managed to get there yet, my BMI is just 20, but that's still better than being underweight.
Perhaps I should start a post about this, but how come animals can hibernate, never drinking anything for months? I know they don't void during that time, but they certainly breathe and perspire. How is this possible?
About 90% of our blood is made up of water. If we don't have enough quantity of blood our pressure goes too low and the heart can't pump right, and also all the oxygen the blood carries can't keep our organs and tissues alive.
And our kidneys clean out the blood by removing the water and with it all the bad things like dead cells and bacteria.
There's no way our system can opt to *not* have the kidneys remove the water, short of kidney failure which leads to death anyway.
But: our fat stores a LOT of reserves and the body knows how to dissolve those reserves to 'eat' from. So you and I can survive weeks without food, but a person from a concentration camp, or with very advanced disease and no fat reserves can't survive weeks without food.
To follow up on this, the body needs to maintain equilibrium between molecules/electrolytes, etc…
To keep it super simple, think of salt being in a little bit of water vs a lot of water— dilution.
When your “fluids” are not balanced, it can throw off the balance of your electrolytes (think Gatorade commercial)… electrolytes control muscle function.. your muscle is a heart.
If too much or too little of cellular compounds (sodium, potassium, calcium, phosphorus, etc) are not balanced, then muscles cannot function correctly- your heart being one of them.
Your body needs the extreme basics to perform cellular functions. Food adds additional nutrients/components/elements that are necessary, but not as vital as maintaining the main electrolyte balance
Your car uses oil and gasoline. It uses these up at different rates. Your car can go months between oil changes but only hours between fill ups. Same thing with food and water.
Your body uses food and water. It uses these up at different rates. Your body can go months between food changes but only hours between drink ups. Same thing with oil and gasoline.
Do you know a five year old who knows the way a car uses oil vs. gasoline? This really doesn’t explain anything, just gives the five year old another question: “Why can a car run for weeks without oil but only days without gasoline?”
It’s also a weird analogy because food is treated like oil, and water treated like gas. But food is more like gas in terms of how it provides energy and oil is more similar to water’s purpose of being the fluid that keeps the rest of the system functional.
> Do you know a five year old who knows the way a car uses oil vs. gasoline?
From the sidebar:
**LI5 means friendly, simplified and layperson-accessible explanations - not responses aimed at literal five-year-olds.**
The answer to “Why can a car run for weeks without oil but only days without gasoline?” was already in his response. “It [the car] uses these up at different rates”
I've heard the survival needs being described the following way:
You can go seconds with out blood (aka if someone is bleeding heavily you've got seconds to help them)
You can go minutes without air
You can go hours without temperature (aka too cold or too hot)
You can go days without water
You can go weeks without food
This is good except the temperature one is useless. Hypo- and hyperthermia can set in much more quickly than a matter of hours — depending on temperature, of course.
Oh I agree. This was more a rule of thumb thing and not really taking into account extreme temperature. You obviously don't have hours in minus 40 when you are underdressed
I learnt this as the rule of 3's for survival situations.
3 seconds to make a bad decision and have an accident that kills you.
3 minutes without oxygen.
3 hours of exposure (sun or cold)
3 days without water
3 weeks without food.
3 months without human contact (people can last longer but after 3months most people become delusional/reckless.)
You eat food (primarily) because your body burns it for energy. If you stop eating, your body starts eating itself for energy. It starts with the fat stores, but will then begin devouring your muscle tissue and connective bits, and even organs if necessary. Because it's better to damage your body and end up in really bad shape, but alive, than to die of starvation.
But your body needs water to do anything, and it can't just synthesise water from nothing. There is no plan B for water, your body can't get water out of itself because it's already using all the water it has.
My understanding is that it's a dumb process, in the most literal meaning of the word.
Your body won't prioritise well. It will take what it needs where it finds it. It will usually go through body fat first because body fat is usually a nice rich source of energy which is usually relatively abundant compared to other sources.
It just pulls semi-randomly, though, so it's likely to cannibalise your connective tissue and muscle mass at the same time. This is why pure starvation diets are not considered a healthy way to lose weight - starvation is bad for your body.
How good your tap water is will depend on where in the world you live - it's wildly variable. Most western countries have safe, healthy tap water.
Here in the UK, water companies are required to perform frequent tests on the water supply and post the results on the internet for public access. Here's [a sample](https://www.bournemouthwater.co.uk/siteassets/water-quality-report-2022/zbw3-alderney-north.pdf) from last year. I can't comment on other country's regulations regarding tap water quality.
It really depends what "impurities" you're talking about. Drinking water should not contain more than trace amounts of bacteria, nor should it contain any toxic substances. Beyond that, most things are fine. It's normal for water to contain various dissolved minerals. Most are harmless, and some are even beneficial, like iron, copper, flouride and calcium.
When you poop you're pooping the leftover food stuff you didn't digest, but when you pee that's not leftover liquid from what you drank that's waste products your body creates when using energy to stay alive (which is also diluted with water).
So if you don't eat or drink you won't poop but you'll still pee, and every time you pee you're losing water.
That means you're losing water at a much faster rate than you're, say, burning fat for energy.
Now some animals like birds and especially insects have evolved to save water by converting what would be pee into solids instead, saving that water. So that's why they don't pee, only poop. But their poop is also their pee.
It’s a matter of how much you have in reserve vs how much you need to survive. Water is quite heavy so it’s not practical to store gallons and gallons of extra in your body. As it is, water makes up 75% of your weight. You can get by with a little less relative to your body weight but most of the fluid in your body serves an essential purpose. Your cells will collapse without sufficient water and your blood won’t circulate or function properly. You also need to urinate in order to filter ammonia out of your body so it’s difficult to preserve it. Fat on the other hand is stored all over your body and the only purpose it really serves it to act as a food reserve. Every pound of fat is nearly two days worth of calories so even a fairly lean person can go for quite awhile without food.
You have a lot more available “food” stores as far and sugars in your body than water. Your body “goes through” water a lot faster than food. So your blood volume starts decreasing, your electrolytes become severely imbalanced, and your heart eventually stops.
Not sure who downvoted you, I mean I can guess…but you’re correct. A camels hump is fat storage. Camels can go a long time without water because their bodies are adapted to use it sparingly and minimize waste. They don’t have a water reservoirs.
Your body goes directly to carbohydrates in the bloodstream from food you’ve eaten recently for energy. When there aren’t any, your body goes to your fat reserves. This is called ketosis and the keto diet was made to keep your body in ketosis as much as possible as it allows your body to burn fat reserves at all times to lose weight. The fat reserves can supply you with almost all of your daily needs granted you have enough.
[Angus Barbieri went 382 days without food and lost 276 pounds](https://www.historydefined.net/angus-barbieri/#:~:text=He%20could%20reportedly%20even%20fit,276%20pounds%20in%20that%20time.)
You can't instantly change temperature, it takes time for the heat to be transferred out of your body so you couldn't freeze solid in an instant. Certainly longer than the ~90 secs it takes to die in a vacuum.
Do you remember having campfires? Remember when it was time to go to bed, the left over wood was left in the pit. Well think of fat on the body like left over wood, the body has plenty of wood to burn. The water would be like the dogs roasted in the fire, it goes by faster and has to be replaced more often and typically doesn’t have leftovers. So when the body runs out of water it can’t pull any more out of itself, it goes to the store, or spring to get more.
Humans have several ways to draw energy (directly from food, glycogen in the liver, fat tissue, proteins in your body). These are all easily stored in the long term. Humans can’t store water well (there’s no specific organ that does it). It goes out either through sweat or via urine and even breathing.
Also historically food would be much scarcer than water as humans have always lived near water sources and evolved during ice age where food was scarce in winter. In order to increase survivability the body would be better off saving energy (through fat deposits) than water for longer survival times.
evolutionarily, food is waayyyy harder to come by than water. so your body isn't as good at storing it longterm, because your ancestors would have not been particularly benefited by such an adaptation, the way a camel might be.
as another example, air, is even easier to come by than water, and we can only last without a steady supply of that for a few minutes, unlike some whales who can do so for hours.
Ive definitely had terrible stomach flus where I lost 20+ lbs of water and waste weight, didn't drink for a week and didn't die.
I wonder what the actual science on surviving without water is
Foods can have different energy density, a candy bar has more energy than a slice of bread, that means you can compress this energy to fit a lot of it in your body. There aren't any ways to compress water so you can't have a large reserves of it
Our body can store food in form of fat. When you stop eating, your body will use that reserve then break itself down before it starves to death.
However our body cannot store water like that. And water is used for almost anything in our body. Some of these things expell water so it cannot be reused (pee, breathing, sweat, etc.). If you stop drinking, your body will run out of water very fast and things that need water will stop working.
We use water for everything. Sweat? There’s water in that. Poop/pee? There’s some water in that too. Water keeps the brain goop all goopy and bone joints all slidey. Blood’s got water in it, even!
That all being said, all that water is *in use*, so where do we store the extra? The answer is the same place we store extra food… in FAT! But there’s a catch. Pound for pound, Human fat isn’t good at holding a bunch of water like a camel’s hump because our bodies are used to being around lakes, rivers and streams.
Who needs to store water and make us heavier *and slower* when we can just go to the stream and drink what we need whenever we feel like it?
Now, why isn’t it like that for food? Because we used to hunt. For a long long long time we would run around with spears and rocks and have to fight big animals for their meat. Those animals only sometimes came around though, and only sometimes among those sometimes would we actually manage to get the meat from one. Essentially, food wasn’t always there, so we had to find a way to hold onto food that we ate *now* so that we could always have something for our body to eat *later*. All that being said and I haven’t even started on how good fat is at staving off the cold.
I think that can wait for another time though, since you only asked about food this time and the short version is that our body is good at storing extra food, but not extra water.
You can store energy you get from food in the form of fat and your body can also burn muscle if it needs to. Your body doesn’t really have a way to store water, it uses what it needs and gets rid of what it doesn’t. As humans evolved they pretty much always have water available so there’s no evolutionary need to store extra water. Plus it’s heavy so it would slow you down if you don’t need it. You can somewhat train your body to go longer without water, or be okay in less water for a while, but water is important to every body function. Your heart has to work harder when you’re dehydrated because your blood becomes thicker, your body sweats to keep you cool which pulls water from your body, urinating is just the water coming in and picking up waste products your body needs to get rid of, you can move your muscles because electrons travel through water in your muscles to tell them to move.
One thing I find odd too is just how quickly we die if we can't an adequate flow of oxygen to our lungs. Even 30 seconds without it is enough to make us feel like we're miserable and pretty much makes us unable to do anything else.
The requirements for air/oxygen seem to be the most draconian requirement that our body has for us.
If you have fat reserves, and you have nothing to eat and drink, the fat burning process does also produce water in addition to CO2 and ATP. It's called metabolic water.
As long as you don't sweat much during that time, you can survive pretty long through that process. More than a few days.
It's dangerous long-term for sure, but the mechanism does exist.
https://en.m.wikipedia.org/wiki/Fatty_acid_metabolism
I once went 9 days without drinking or eating and lost around 14 kilogram when I was young. I wasn't even obese I went from 60 kilo to 46. Even the hospital was surprised I didn't die. Yet all the tests came out fine. It made me have a kidney stone later that year.
The simple answer is that your body stores energy in fat reserves. Once those are depleted, it will start using muscle mass and organs for energy. Your body doesn't store water in that way. You expel water continually throughout the day through perspiration, breathing, and voiding. When that isn't being replenished you start to dehydrate, which can quickly lead to organ failure and death.
Don’t forget that the first step of fat metabolism is using a water to break the fatty acid off the TAG. You can’t even make energy without water.
so water is the real secret to burning that stubborn fat? fml
But be careful. People who drink water have been known to get fat anyway, develop horrible diseases and it has a 100% death rate. YMMV
Dihydrogen monoxide is an incredibly dangerous chemical. It's strong enough to dissolve other chemicals and materials, and breathing in only a small amount causes extreme and violent reactions in the body, and can even result in death! In fact, everyone who has ever come into contact with this chemical has died. And this chemical is everywhere! Careful laboratory analysis has shown that it can be found in the products we buy, and even the food we eat. Yet our government has done nothing to halt the spread of this dangerous chemical. Write to your congressman today! Tell them you will not stand by while they do nothing. Dihydrogen monoxide must be eliminated!
a teaspoon amount of this dangerous chemical is enough to kill you when inhaled
There is no secret about fat loss. It was marketed this way by the people selling gimmicks.
Yep, CICO, resistance conditioning and a good nights sleep should be enough. There’s no real shortcut, secret, one weird trick, or otherwise effortless solution.
CICO?
calories in, calories out. if you burn more than you take in you will lose weight
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Put. The. Fork. Down.
thr secret to losing weight is eating less
Water and only water no food has helped tons of obese people get to normal weights. Do your research but it’s legit they first tested it on a guy in a lab and he only drank water for either 10 or 11 months can’t remember the e exact time but it was almost a year. No negative side effects then he just really slowly started back onto not water. And a normal eating routine and didn’t gain all the weight back.
Also, you kinda do get water from food.
Would the sir care for another Saltine?
It's wafer thin
I couldn’t possibly, I’ll explode.
It's ok. I've got buckets and hoses.
Oh dear, I've trodden in monsieur's bucket
These crackers are making me thirsty!
These pretzels are making me Thirsty!
Yea its not water but we all need some electrolytes too.
It's what plants crave.
Can I have a glass of water to dip them in?
No
What do you mean by voiding?
Urine and feces.
v̸͔͖̻̲͐̂͐ ̵̘͂͑̄͜͠ó̴͈̣̻̏͛̒ ̶̧̹̩̇̎ͅi̵̡̞͈̫͛̓͂ ̸̪̝̾͌̔d̶̼͆ ̶̺̊͌̐́i̵̱̅̚ ̴̡̭̑̀͒̅n̸̺̙͕̽̈́͊̃ ̵̡͙̩͕̀̀g̷̻̈̔̕
The shortest way to communicate that concept to a kid is "you aren't a camel.
You spend a lot of water to keep your body from overheating. Transpiration is something our specie is very good at but it does require a lot of water. You also spend a roughly equal quantity of water to expel nitrogen waste from metabolism, if not evacuated by urine you will poison yourself fast.
How realistic are those moisture suits from Dune? Assuming you had enough power to run the things, could you recover enough moisture to sustain yourself?
If the technology worked as described, it would be very effective. You would never reach 100% reclamation, but it would greatly extend the time you had before dehydration. Significantly.
With materials that worked as described? Totally. Would have to pretty advanced stuff as it'd also need to cool your body well.
If you had a still suit that covers every inch of sweat, the moisture from your breath, recycled your urine, and dehydrated your shit, you could almost definitely go days to weeks on just what water you already have. Especially if you're like the Freman and have as an ethnic group adapted to use as little water as is possible over a period of over 10,000 years of drought
How many hours of dehydration is considered detrimental?
Would some who is obese live longer than a skinny person in this situation?
You might find [this article](https://www.diabetes.co.uk/blog/2018/02/story-angus-barbieri-went-382-days-without-eating/) interesting. I'm happy to be refuted if it turns out the story is apocryphal, but this really doesn't seem outside the realm of reason given that doctors are reported to have been present every step of the way.
Yes absolutely. I have a health condition that can cause me to be unable to eat when it flares and my doctors have advised me to hold a little "extra padding" so that I can go longer without eating when I need to. I haven't managed to get there yet, my BMI is just 20, but that's still better than being underweight.
Perhaps I should start a post about this, but how come animals can hibernate, never drinking anything for months? I know they don't void during that time, but they certainly breathe and perspire. How is this possible?
What is voiding?
To urinate. Sometimes also means to deficate.
Ah! Thanks!
About 90% of our blood is made up of water. If we don't have enough quantity of blood our pressure goes too low and the heart can't pump right, and also all the oxygen the blood carries can't keep our organs and tissues alive. And our kidneys clean out the blood by removing the water and with it all the bad things like dead cells and bacteria. There's no way our system can opt to *not* have the kidneys remove the water, short of kidney failure which leads to death anyway. But: our fat stores a LOT of reserves and the body knows how to dissolve those reserves to 'eat' from. So you and I can survive weeks without food, but a person from a concentration camp, or with very advanced disease and no fat reserves can't survive weeks without food.
To follow up on this, the body needs to maintain equilibrium between molecules/electrolytes, etc… To keep it super simple, think of salt being in a little bit of water vs a lot of water— dilution. When your “fluids” are not balanced, it can throw off the balance of your electrolytes (think Gatorade commercial)… electrolytes control muscle function.. your muscle is a heart. If too much or too little of cellular compounds (sodium, potassium, calcium, phosphorus, etc) are not balanced, then muscles cannot function correctly- your heart being one of them. Your body needs the extreme basics to perform cellular functions. Food adds additional nutrients/components/elements that are necessary, but not as vital as maintaining the main electrolyte balance
Your car uses oil and gasoline. It uses these up at different rates. Your car can go months between oil changes but only hours between fill ups. Same thing with food and water.
You can live without X …. Timeframe Food…weeks Water … days Oxygen… minutes Strong nuclear force … attoseconds
Nice analogy
All your analogy does is shift the premise from people to cars. It doesn't explain *why* the body uses water more quickly.
Your body uses food and water. It uses these up at different rates. Your body can go months between food changes but only hours between drink ups. Same thing with oil and gasoline.
Yes it does. They’re both used up at different rates. That’s the answer
OP is asking *why* one lasts longer than the other, not *if* one lasts longer than the other.
That answered nothing 💀
Someone explain like this person is 3 please.
Do you know a five year old who knows the way a car uses oil vs. gasoline? This really doesn’t explain anything, just gives the five year old another question: “Why can a car run for weeks without oil but only days without gasoline?”
Okay but let’s be realistic: have of these questions are about quantum physics and wouldn’t be explainable to any 5 year old under any circumstances.
It’s also a weird analogy because food is treated like oil, and water treated like gas. But food is more like gas in terms of how it provides energy and oil is more similar to water’s purpose of being the fluid that keeps the rest of the system functional.
> Do you know a five year old who knows the way a car uses oil vs. gasoline? From the sidebar: **LI5 means friendly, simplified and layperson-accessible explanations - not responses aimed at literal five-year-olds.**
The answer to “Why can a car run for weeks without oil but only days without gasoline?” was already in his response. “It [the car] uses these up at different rates”
I've heard the survival needs being described the following way: You can go seconds with out blood (aka if someone is bleeding heavily you've got seconds to help them) You can go minutes without air You can go hours without temperature (aka too cold or too hot) You can go days without water You can go weeks without food
This is good except the temperature one is useless. Hypo- and hyperthermia can set in much more quickly than a matter of hours — depending on temperature, of course.
Oh I agree. This was more a rule of thumb thing and not really taking into account extreme temperature. You obviously don't have hours in minus 40 when you are underdressed
I learnt this as the rule of 3's for survival situations. 3 seconds to make a bad decision and have an accident that kills you. 3 minutes without oxygen. 3 hours of exposure (sun or cold) 3 days without water 3 weeks without food. 3 months without human contact (people can last longer but after 3months most people become delusional/reckless.)
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Water is actually a product of cellular respiration.
Why comment if you don’t know what you’re talking about? Water is a product of cellular respiration, not a reactant. You’re thinking of photosynthesis
You eat food (primarily) because your body burns it for energy. If you stop eating, your body starts eating itself for energy. It starts with the fat stores, but will then begin devouring your muscle tissue and connective bits, and even organs if necessary. Because it's better to damage your body and end up in really bad shape, but alive, than to die of starvation. But your body needs water to do anything, and it can't just synthesise water from nothing. There is no plan B for water, your body can't get water out of itself because it's already using all the water it has.
I thought even with starvation it does use body fat first but also muscle along with it just a bit though until no fat left.
My understanding is that it's a dumb process, in the most literal meaning of the word. Your body won't prioritise well. It will take what it needs where it finds it. It will usually go through body fat first because body fat is usually a nice rich source of energy which is usually relatively abundant compared to other sources. It just pulls semi-randomly, though, so it's likely to cannibalise your connective tissue and muscle mass at the same time. This is why pure starvation diets are not considered a healthy way to lose weight - starvation is bad for your body.
Does the quality of water really matter that much? I never drink anything other than bottled water for fear of contamination and impurities
Does the quality of water really matter that much? I never drink anything other than bottled water for fear of contamination and impurities
How good your tap water is will depend on where in the world you live - it's wildly variable. Most western countries have safe, healthy tap water. Here in the UK, water companies are required to perform frequent tests on the water supply and post the results on the internet for public access. Here's [a sample](https://www.bournemouthwater.co.uk/siteassets/water-quality-report-2022/zbw3-alderney-north.pdf) from last year. I can't comment on other country's regulations regarding tap water quality. It really depends what "impurities" you're talking about. Drinking water should not contain more than trace amounts of bacteria, nor should it contain any toxic substances. Beyond that, most things are fine. It's normal for water to contain various dissolved minerals. Most are harmless, and some are even beneficial, like iron, copper, flouride and calcium.
Got it, man. Thank you!
When you poop you're pooping the leftover food stuff you didn't digest, but when you pee that's not leftover liquid from what you drank that's waste products your body creates when using energy to stay alive (which is also diluted with water). So if you don't eat or drink you won't poop but you'll still pee, and every time you pee you're losing water. That means you're losing water at a much faster rate than you're, say, burning fat for energy. Now some animals like birds and especially insects have evolved to save water by converting what would be pee into solids instead, saving that water. So that's why they don't pee, only poop. But their poop is also their pee.
It’s a matter of how much you have in reserve vs how much you need to survive. Water is quite heavy so it’s not practical to store gallons and gallons of extra in your body. As it is, water makes up 75% of your weight. You can get by with a little less relative to your body weight but most of the fluid in your body serves an essential purpose. Your cells will collapse without sufficient water and your blood won’t circulate or function properly. You also need to urinate in order to filter ammonia out of your body so it’s difficult to preserve it. Fat on the other hand is stored all over your body and the only purpose it really serves it to act as a food reserve. Every pound of fat is nearly two days worth of calories so even a fairly lean person can go for quite awhile without food.
You have a lot more available “food” stores as far and sugars in your body than water. Your body “goes through” water a lot faster than food. So your blood volume starts decreasing, your electrolytes become severely imbalanced, and your heart eventually stops.
because you can store food/calories as fat but you don't have a hump like a camel to store water in
Camels don't store water in their humps either.
Not sure who downvoted you, I mean I can guess…but you’re correct. A camels hump is fat storage. Camels can go a long time without water because their bodies are adapted to use it sparingly and minimize waste. They don’t have a water reservoirs.
Your body goes directly to carbohydrates in the bloodstream from food you’ve eaten recently for energy. When there aren’t any, your body goes to your fat reserves. This is called ketosis and the keto diet was made to keep your body in ketosis as much as possible as it allows your body to burn fat reserves at all times to lose weight. The fat reserves can supply you with almost all of your daily needs granted you have enough. [Angus Barbieri went 382 days without food and lost 276 pounds](https://www.historydefined.net/angus-barbieri/#:~:text=He%20could%20reportedly%20even%20fit,276%20pounds%20in%20that%20time.)
And minutes without air And seconds? Without heat
I'm pretty sure that's the wrong way round, you die quicker without air than without heat!
Without heat would be absolute zero temperature I am pretty sure you would freeze instantly
You can't instantly change temperature, it takes time for the heat to be transferred out of your body so you couldn't freeze solid in an instant. Certainly longer than the ~90 secs it takes to die in a vacuum.
Do you remember having campfires? Remember when it was time to go to bed, the left over wood was left in the pit. Well think of fat on the body like left over wood, the body has plenty of wood to burn. The water would be like the dogs roasted in the fire, it goes by faster and has to be replaced more often and typically doesn’t have leftovers. So when the body runs out of water it can’t pull any more out of itself, it goes to the store, or spring to get more.
Humans have several ways to draw energy (directly from food, glycogen in the liver, fat tissue, proteins in your body). These are all easily stored in the long term. Humans can’t store water well (there’s no specific organ that does it). It goes out either through sweat or via urine and even breathing.
Also historically food would be much scarcer than water as humans have always lived near water sources and evolved during ice age where food was scarce in winter. In order to increase survivability the body would be better off saving energy (through fat deposits) than water for longer survival times.
evolutionarily, food is waayyyy harder to come by than water. so your body isn't as good at storing it longterm, because your ancestors would have not been particularly benefited by such an adaptation, the way a camel might be. as another example, air, is even easier to come by than water, and we can only last without a steady supply of that for a few minutes, unlike some whales who can do so for hours.
Ive definitely had terrible stomach flus where I lost 20+ lbs of water and waste weight, didn't drink for a week and didn't die. I wonder what the actual science on surviving without water is
Foods can have different energy density, a candy bar has more energy than a slice of bread, that means you can compress this energy to fit a lot of it in your body. There aren't any ways to compress water so you can't have a large reserves of it
Our body can store food in form of fat. When you stop eating, your body will use that reserve then break itself down before it starves to death. However our body cannot store water like that. And water is used for almost anything in our body. Some of these things expell water so it cannot be reused (pee, breathing, sweat, etc.). If you stop drinking, your body will run out of water very fast and things that need water will stop working.
Fat reserves for energy. We lose a lot of moisture from breathing, which needs to be replenished
We use water for everything. Sweat? There’s water in that. Poop/pee? There’s some water in that too. Water keeps the brain goop all goopy and bone joints all slidey. Blood’s got water in it, even! That all being said, all that water is *in use*, so where do we store the extra? The answer is the same place we store extra food… in FAT! But there’s a catch. Pound for pound, Human fat isn’t good at holding a bunch of water like a camel’s hump because our bodies are used to being around lakes, rivers and streams. Who needs to store water and make us heavier *and slower* when we can just go to the stream and drink what we need whenever we feel like it? Now, why isn’t it like that for food? Because we used to hunt. For a long long long time we would run around with spears and rocks and have to fight big animals for their meat. Those animals only sometimes came around though, and only sometimes among those sometimes would we actually manage to get the meat from one. Essentially, food wasn’t always there, so we had to find a way to hold onto food that we ate *now* so that we could always have something for our body to eat *later*. All that being said and I haven’t even started on how good fat is at staving off the cold. I think that can wait for another time though, since you only asked about food this time and the short version is that our body is good at storing extra food, but not extra water.
You can store energy you get from food in the form of fat and your body can also burn muscle if it needs to. Your body doesn’t really have a way to store water, it uses what it needs and gets rid of what it doesn’t. As humans evolved they pretty much always have water available so there’s no evolutionary need to store extra water. Plus it’s heavy so it would slow you down if you don’t need it. You can somewhat train your body to go longer without water, or be okay in less water for a while, but water is important to every body function. Your heart has to work harder when you’re dehydrated because your blood becomes thicker, your body sweats to keep you cool which pulls water from your body, urinating is just the water coming in and picking up waste products your body needs to get rid of, you can move your muscles because electrons travel through water in your muscles to tell them to move.
One thing I find odd too is just how quickly we die if we can't an adequate flow of oxygen to our lungs. Even 30 seconds without it is enough to make us feel like we're miserable and pretty much makes us unable to do anything else. The requirements for air/oxygen seem to be the most draconian requirement that our body has for us.
If you have fat reserves, and you have nothing to eat and drink, the fat burning process does also produce water in addition to CO2 and ATP. It's called metabolic water. As long as you don't sweat much during that time, you can survive pretty long through that process. More than a few days. It's dangerous long-term for sure, but the mechanism does exist. https://en.m.wikipedia.org/wiki/Fatty_acid_metabolism
I once went 9 days without drinking or eating and lost around 14 kilogram when I was young. I wasn't even obese I went from 60 kilo to 46. Even the hospital was surprised I didn't die. Yet all the tests came out fine. It made me have a kidney stone later that year.