Does eating snow dehydrate you?

[Drathnoxis]

I recently heard this myth, and after an hour of googling and coming across some articles that claim it does and some that claim it doesn't, neither presenting any good sources or hard science, I'm turning to the Escapist forums for the definitive answer.

Now as I understand the myth, the idea is that eating snow will lower your core temperature which will require your body to burn calories to increase heat which somehow consumes more water than will be replenished by the melting of the snow. I don't understand this because my high school chemistry (didn't take biology) tells me that your body's chemical processes run off of a combustion reaction, the products of which are water and carbon dioxide, so I'm unsure as to where the consumption of water comes into effect?

Now obviously eating snow is bad for a lot of reasons (pollutants, bacteria, pee, hypothermia) but what I want to know is this: if you are trapped on a mountain for a week without means of melting snow before consuming it, would your net hydration increase or decrease as a result of said consumption and why?

I believe a few people here(or used to be here) have more of a medical background and will hopefully have further insight into the question than myself.

 

[Xprimentyl]

I recently heard this myth, and after an hour of googling... I'm turning to the Escapist forums for the definitive answer.

There's your first mistake.

Now as I understand the myth, the idea is that eating snow will lower your core temperature which will require your body to burn calories to increase heat which somehow consumes more water than will be replenished by the melting of the snow. I don't understand this because my high school chemistry (didn't take biology) tells me that your body's chemical processes run off of a combustion reaction, the products of which are water and carbon dioxide, so I'm unsure as to where the consumption of water comes into effect?

Now obviously eating snow is bad for a lot of reasons (pollutants, bacteria, pee, hypothermia) but what I want to know is this: if you are trapped on a mountain for a week without means of melting snow before consuming it, would your net hydration increase or decrease as a result of said consumption and why?

I believe a few people here(or used to be here) have more of a medical background and will hopefully have further insight into the question than myself.

Your second mistake will be listening to anything I have to say.

Science and biology are far from my strong suits, but making a series of logical deductions, I'd wager eating snow wouldn't dehydrate you. By the time snow reaches the point of it actually being processed by your body, it's melted; it's cold water at best. It can't stay cold enough long enough to appreciably lower your core temperature via consumption. Your mouth's temperature? Sure. But your core temperature, as in the net temperature of your internal organs? No. I mean, you'd have to eat massive amounts of snow very rapidly to drop the core temperature of a healthy adult into dangerous areas which I think it a physiological impossibility.

I think the only time you'd have to worry about that is if you're stranded in the elements and your core temperature is already being affected by the environment. At that point, if the consumption of snow can drop your core temperature into unsafe levels... let's just say, you've probably already succumbed to hypothermia and have been dead for a few hours, so dehydration from snow eating is probably the least of your concerns.

 

[Drathnoxis]

Your second mistake will be listening to anything I have to say.

Science and biology are far from my strong suits, but making a series of logical deductions, I'd wager eating snow wouldn't dehydrate you. By the time snow reaches the point of it actually being processed by your body, it's melted; it's cold water at best. It can't stay cold enough long enough to appreciably lower your core temperature via consumption. Your mouth's temperature? Sure. But your core temperature, as in the net temperature of your internal organs? No. I mean, you'd have to eat massive amounts of snow very rapidly to drop the core temperature of a healthy adult into dangerous areas which I think it a physiological impossibility.

Exactly the sort of response I'd expect from a Texan.

Melting ice actually takes a huge amount of energy compared to simply raising the temperature of it. It takes 334 J to melt 1g of ice at 0°C, compared to 4.18 J to raise the temperature of 1g of water 1°C.

I think the only time you'd have to worry about that is if you're stranded in the elements and your core temperature is already being affected by the environment. At that point, if the consumption of snow can drop your core temperature into unsafe levels... let's just say, you've probably already succumbed to hypothermia and have been dead for a few hours, so dehydration from snow eating is probably the least of your concerns.

I was talking about a survival situation, but yeah, my read on it is also that hypothermia will get you before dehydration.

 

[Xprimentyl]

Exactly the sort of response I'd expect from a Texan.

Not a Texan; I just live here.

Melting ice actually takes a huge amount of energy compared to simply raising the temperature of it. It takes 334 J to melt 1g of ice at 0°C, compared to 4.18 J to raise the temperature of 1g of water 1°C.

Like I said, science isn't a strong suit of mine, but isn't "melting" the process of "raising the temperature?" And while snow is technically "ice," I'd assume it takes substantially less energy to melt a gram of snow versus a gram of solid ice.

 

[EvilRoy]

So, it's a bad idea to eat snow for water because as you said you'll drop your core temp. You can also get frostbite on your tongue and gums, which is exactly as horrible as it sounds. If you're just like, going outside and munching on it like a weirdo and coming back in then it won't do much, but in 20 below you can significantly reduce your survival time by eating snow if you don't have a nearby heatsource.

In order for eating snow to dehydrate you it would need to make you sweat, but sweating in extreme cold will kill you way faster than dehydration even if it wasn't counterintuitive. Sure it'll make you burn energy, but realistically not much more than the energy you're already burning trying not to freeze solid. When I worked in the oilsands I would often see guys shove bags of snow into their coats and pants to keep themselves from sweating when they climbed up towers. Getting up there sweating and having the wind hit you would be hell.

 

[Caperf]

These are honestly the questions that keep me up at night.

 

[Drathnoxis]

Not a Texan; I just live here.



Like I said, science isn't a strong suit of mine, but isn't "melting" the process of "raising the temperature?" And while snow is technically "ice," I'd assume it takes substantially less energy to melt a gram of snow versus a gram of solid ice.

It would take exactly the same energy to melt 1g of snow as 1g of ice, the snow would just take up a larger area and would possibly melt faster as a result of the larger surface area. The reason it takes more energy to melt the snow is because phase changes involve something called latent heat. If you had a pot of snow with a thermometer in it reading -20°C and began heating it, the temperature would rise until it reached 0°C(melting point), then it would remain at 0°C until all of the snow had melted as all the energy is going towards breaking the bonds between the ice molecules, then the temperature would begin to rise again and the same thing would happen at 100°C(boiling point).

Incidentally, this large energy transfer at a phase change is part of what makes refrigeration systems possible.

 

[Agema]

Now as I understand the myth, the idea is that eating snow will lower your core temperature which will require your body to burn calories to increase heat which somehow consumes more water than will be replenished by the melting of the snow.

You lose water chiefly through respiration, sweating, and urination. If your metabolism works hard, it doesn't necessarily mean water will be lost from the body - it's actually dependent on the routes of water loss.

Normally water loss will be increased by metabolism, because that means exercise, and exercise means increased breathing and sweating. But if you're very cold, you might not be breathing much more or sweating much even though the body is increasing metabolism to increase temperature. The problem with eating snow in this situation is more hypothermia if it's very cold, or with long-term survival with limited food, where you're burning more calories keeping warm and increasing risk of starvation.

So the simple answer with whether you should eat snow is that it depends on whether you're more likely to die of dehydration or hypothermia / starvation.

Incidentally, you might also want to avoid eating snow because it traps a great deal of other chemicals (e.g. pollution). That's not good for you either - although again, dehydration may be a more immediate concern.

 

[Xprimentyl]

You lose water chiefly through respiration, sweating, and urination. If your metabolism works hard, it doesn't necessarily mean water will be lost from the body - it's actually dependent on the routes of water loss.

Normally water loss will be increased by metabolism, because that means exercise, and exercise means increased breathing and sweating. But if you're very cold, you might not be breathing much more or sweating much even though the body is increasing metabolism to increase temperature. The problem with eating snow in this situation is more hypothermia if it's very cold, or with long-term survival with limited food, where you're burning more calories keeping warm and increasing risk of starvation.

So the simple answer with whether you should eat snow is that it depends on whether you're more likely to die of dehydration or hypothermia / starvation.

Incidentally, you might also want to avoid eating snow because it traps a great deal of other chemicals (e.g. pollution). That's not good for you either - although again, dehydration may be a more immediate concern.

See? Even in my ignorance, I wasn't far off in my initial assumption. *stares down nose at @Drathnoxis*

 

[Agema]

In order for eating snow to dehydrate you it would need to make you sweat, but sweating in extreme cold will kill you way faster than dehydration even if it wasn't counterintuitive. Sure it'll make you burn energy, but realistically not much more than the energy you're already burning trying not to freeze solid. When I worked in the oilsands I would often see guys shove bags of snow into their coats and pants to keep themselves from sweating when they climbed up towers. Getting up there sweating and having the wind hit you would be hell.

Yes - one survival technique I've read about is that if you are going to do some heavy activity in cold weather, remove some of your clothing (depends how cold and so on, though). The activity should keep you warm, and more sweat will evaporate with fewer layers. This means that when you stop being active and cool down, you'll have less moisture to chill you even further.

 

[Drathnoxis]

You lose water chiefly through respiration, sweating, and urination. If your metabolism works hard, it doesn't necessarily mean water will be lost from the body - it's actually dependent on the routes of water loss.

Normally water loss will be increased by metabolism, because that means exercise, and exercise means increased breathing and sweating. But if you're very cold, you might not be breathing much more or sweating much even though the body is increasing metabolism to increase temperature. The problem with eating snow in this situation is more hypothermia if it's very cold, or with long-term survival with limited food, where you're burning more calories keeping warm and increasing risk of starvation.

So the simple answer with whether you should eat snow is that it depends on whether you're more likely to die of dehydration or hypothermia / starvation.

Incidentally, you might also want to avoid eating snow because it traps a great deal of other chemicals (e.g. pollution). That's not good for you either - although again, dehydration may be a more immediate concern.

So the basis of the myth is caused by conflating increased metabolism with increased breathing and sweat, which isn't necessarily the case. Ok thanks!

Also, just now I found a Stack Exchange thread on the topic that agrees with the consensus of our thread. Don't know why it didn't turn up earlier.

See? Even in my ignorance, I wasn't far off in my initial assumption. *stares down nose at @Drathnoxis*

What, hey! I agreed with you about the danger being hypothermia not dehydration. I just thought it was funny how your post was obviously written by someone who lives somewhere that doesn't ever get cold.

 

[Xprimentyl]

Yes - one survival technique I've read about is that if you are going to do some heavy activity in cold weather, remove some of your clothing (depends how cold and so on, though). The activity should keep you warm, and more sweat will evaporate with fewer layers. This means that when you stop being active and cool down, you'll have less moisture to chill you even further.

The fact that such survival tactics exist serves as a constant reminder that I'm perfectly happy staying at home and avoiding adventures that take me more than 5 miles from the nearest Walmart. A girl I dated took me on a hike (yellow flag,) and as we were walking, a jogger going in the opposite direction cheerily cautioned us that a mama bear and her cub were further up the trail in the direction we were headed. I stopped immediately; my girlfriend got all excited like the bears were puppies (RED flag.) I told her we were done, turning around and going home, and she was genuinely disappointed.

It boggles my mind that people actually have that adventurous spirit that puts them in clear danger and have to develop survival skills (aka: skills to fall back on when common sense left them high and dry.) Were it up to me and my fear of the unknown, there'd be no oceanic travel, planes, and certainly space would remain a mystery forever. I'm a coward, but I'm alive.

What, hey! I agreed with you about the danger being hypothermia not dehydration. I just thought it was funny how your post was obviously written by someone who lives somewhere that doesn't ever get cold.

"Doesn't ever get cold???" Did you not hear the news from February where the cold killed our power grid and shut the state down?? Millions died!! Tens of thousands were injured!! Homelessness surged 142%!! We had to eat our cat, slow roasted over a Bic lighter, just to survive!! And most critically, my penchant for exaggeration skyrocketed!!

But seriously, I'm about as urban as it gets; if you ever find me in a situation where I'm pondering eating snow to survive, I've been abducted, taken somewhere remote and have just escaped my captors. I'll never willingly put myself in a situation where I have to weigh the feasibilities of eating snow to live.

 

[Drathnoxis]

"Doesn't ever get cold???" Did you not hear the news from February where the cold killed our power grid and shut the state down?? Millions died!! Tens of thousands were injured!! Homelessness surged 142%!! We had to eat our cat, slow roasted over a Bic lighter, just to survive!! And most critically, my penchant for exaggeration skyrocketed!!

But seriously, I'm about as urban as it gets; if you ever find me in a situation where I'm pondering eating snow to survive, I've been abducted, taken somewhere remote and have just escaped my captors. I'll never willingly put myself in a situation where I have to weigh the feasibilities of eating snow to live.

I mean -20°C is kind of cold. In an average day in winter sort of way.

 

[Thaluikhain]

Yes - one survival technique I've read about is that if you are going to do some heavy activity in cold weather, remove some of your clothing (depends how cold and so on, though). The activity should keep you warm, and more sweat will evaporate with fewer layers. This means that when you stop being active and cool down, you'll have less moisture to chill you even further.

Or sweat less, yeah. If you are wearing enough to be warm when you aren't doing anything, you are wearing too much for when you are doing things. Apparently a common mistake people make.

 

[Bob_McMillan]

I do feel a little parched after having a snow cone.

 

[Agema]

The fact that such survival tactics exist serves as a constant reminder that I'm perfectly happy staying at home and avoiding adventures that take me more than 5 miles from the nearest Walmart. A girl I dated took me on a hike (yellow flag,) and as we were walking, a jogger going in the opposite direction cheerily cautioned us that a mama bear and her cub were further up the trail in the direction we were headed. I stopped immediately; my girlfriend got all excited like the bears were puppies (RED flag.) I told her we were done, turning around and going home, and she was genuinely disappointed.

Yeah, we killed all our country's bears a few centuries ago. I think they've recently re-introduced wolves in a couple of places, but they are much, much lower risk. Stay well away from bears. They probably won't bother you if you keep a respectable distance, but do you really want to take the chance?

A simple basis for this - not really survival - is for instance hillwalking. The top of a hill or small mountain tends to be colder than the bottom, so start wearing light clothing, particularly as the exertion from going uphill is going to generate a lot of heat (potentially worth about 10.C equivalent). Once you're at the top, start adding layers on as required.

Earlier this year I made the mistake of going on a hillwalk when it was 30.C. I'd taken about twice as much water as I normally would for a similar hike at 15-20.C, and it was not enough. I'd only gone about 4 miles and up the first hill (~500m), was already low on water and I think had mild heat exhaustion, so cut it short.

 

[Terminal Blue]

The fact that such survival tactics exist serves as a constant reminder that I'm perfectly happy staying at home and avoiding adventures that take me more than 5 miles from the nearest Walmart. A girl I dated took me on a hike (yellow flag,) and as we were walking, a jogger going in the opposite direction cheerily cautioned us that a mama bear and her cub were further up the trail in the direction we were headed. I stopped immediately; my girlfriend got all excited like the bears were puppies (RED flag.) I told her we were done, turning around and going home, and she was genuinely disappointed.

I feel like you made the correct decision.

Bears are one of those animals that's just clever enough to be unpredictable in their behaviour, and just stupid enough to be easily surprised.

If the advice for how to maximize your chances of surviving an animal encounter takes a solid 5 minutes to explain, that animal is probably best avoided.

 

[Agema]

If the advice for how to maximize your chances of surviving an animal encounter takes a solid 5 minutes to explain, that animal is probably best avoided.

One thing I have noticed is that everyone I know with experience of being in bear country has different advice for how to survive if one decides to go for you.

Which suggests to me your chances amount to nothing more than dumb luck whether or not the bear decides to kill you.

 

[Ravinoff]

One thing I have noticed is that everyone I know with experience of being in bear country has different advice for how to survive if one decides to go for you.

Which suggests to me your chances amount to nothing more than dumb luck whether or not the bear decides to kill you.

If it's black bear territory, you're generally pretty safe. They very rarely attack humans, and when they do it's not usually intending to kill unless the animal is starving. Now I'm not saying to go try petting one, but if you look around there's a ton of videos out there of black bears running away from humans, cows...pretty sure I saw one with a cat even. We've got the biggest black bear subspecies in North America here and anybody who's spent much time in the woods will tell you to be more concerned with moose (those things are a fucking menace, especially during mating season).

Brown bear variants and polar bears though? Yeah, they don't fuck around, you don't leave the house without a rifle in Svalbard
(not kidding, look it up), and in parts of Canada it's customary to not lock car and house doors in bear season in case someone needs a place to hide.

 

[Xprimentyl]

Brown bear variants and polar bears though? Yeah, they don't fuck around, you don't leave the house without a rifle in Svalbard
(not kidding, look it up), and in parts of Canada it's customary to not lock car and house doors in bear season in case someone needs a place to hide.

See, why? Why do people insist on living in places where Mother Nature has clearly stated "it's still my turn, and I'm not done here."