Should I pee or hold it to stay warm?

[gary350]

Summary: Should I pee or hold it to stay warm?

This was on TV many years ago several people were lost in freezing cold weather. One person needed to pee but another person said no hold it as long as you can it keeps you warm. Another person insisted your body generates a fixed about of BTUs of heat it is better to pee to reduce your body mass this will keep you warmer.

Which will keep you warmer, pee or hold it?

 

[berkeman]

(Moved to the Biology forum)

There are several mechanisms in play, but IMO you should pee to relieve the stress. Stress wastes energy, and in survival situations, conserving energy is usually important. You are not lowering your temperature when you pee, you are just getting rid of some volume at the same temperature as the rest of your body.

 

[berkeman]

but IMO you should pee to relieve the stress.

That said, what should you do in a hot desert survival situation? Yuck.

 

[russ_watters]

That said, what should you do in a hot desert survival situation? Yuck.

Chop off your arm sooner.

 

[Rive]

... another person said ... Another person insisted...

Both reasoning is false I think. It does not keep you warm, since it does not generate heat: also, it does not consume heat since it is always warm as long it is inside.

I think the key point is, that you are supposed to open your trousers before you pee. Now, that will make you lose heat...

 

[DaveC426913]

Pee is the same temp as the rest of your body. It doesn't keep you warm. All it really does is provide more mass. And water is an excellent holder of heat.

Greater body mass/volume - for what it's worth - is better for staying warm in a similar way to a large person being able stay warm longer than a thin/small person.

In a nutshell, a 90kg person who pees out a litre of water now has the heat capacity of an 89kg person.

 

[gary350]

If you pee you loose 6 ounces of mass that is 98 degrees. When weather is cold your body will get cold a tiny bit slower with that extra 6 ounces of heat. If you have 2 ice chests 1 with 100 ounces of 98 degree water the other with 95 ounces of 98 degree water the larger mass will cool slower. But what if you put a small heater in each ice chest will the larger mass be harder to keep warm?

 

[DaveC426913]

But what if you put a small heater in each ice chest will the larger mass be harder to keep warm?

No. It will be easier.

Consider the extreme case: 100 small chests each with a litre of water and a heater.
Every one of them will have a harder time holding on to its heat than one 100 litre container of water.

 

[hutchphd]

But the thing you really must do to conserve heat is stop breathing. The worst part is your exhaled breath is nearly 100% relative humidity at 100F and the cold incoming air is ~0 on a cold day and your body "boils" all that water.

 

[jim mcnamara]

@hutchphd While you are correct and humorous, consider that about 40% of human radiative heat loss is through the head and neck.

"if your hands are cold, put on a hat" is a standard mountaineering/hiking concept.

Peeing is not on the list, except that wetting your pants in deep cold can be fatal. Read the 'Gulag Archipelago'

 

[DaveC426913]

@hutchphd While you are correct and humorous, consider that about 40% of human radiative heat loss is through the head and neck.

Apparently, this is an apocryphal myth.

"... the head accounts for about 7 percent of the body’s surface area, and the heat loss is fairly proportional to the amount of skin that’s showing.

At most, according to a 2008 report in BMJ, a person loses 7 percent to 10 percent of their body heat through their head..."

https://www.livescience.com/34411-body-heat-loss-head.html

 

[jim mcnamara]

Not apocryphal
https://link.springer.com/article/10.1007/BF02447222This contends that heat loss by human skin was very important when humans evolved on the savannah, and that hair mediates radiative and evaporative heat loss/gain, and was selected for. Because in part, the head was a major source of heat transfer.

YMMV.

 

[marcusl]

Advice from the Boy Scouts is to get rid of it. There’s no sense being uncomfortable as well as cold.

 

[DaveC426913]

Not apocryphal
https://link.springer.com/article/10.1007/BF02447222This contends that heat loss by human skin was very important when humans evolved on the savannah, and that hair mediates radiative and evaporative heat loss/gain, and was selected for. Because in part, the head was a major source of heat transfer.

YMMV.

Erm. Whatever the theory is/was of why it might be so, I think the point was that recent studies attempted to reproduce the effect and concluded that, per unit skin surface, heat loss via the head was no more than anywhere else on the body.

 

[Rive]

Apparently, this is an apocryphal myth.

Instead, it is a very practical rule-of-thumb. From the link you provided:

This heat-loss myth probably came from experiments in the 1950s, when military researchers exposed subjects to frigid temperatures. While their bodies were bundled up, their heads were exposed — and they were found to have lost more heat from their noggins.

Further on:

In 2006, scientists ... tested subjects in cold water...

In short: despite the poorly dressed marketing word salad in the article the original claim within its context is still true: it fails only if you take a full body ice-bath (or running around naked in the snow).

I do not plan to do any of that, ever: so I still safe to choose to accept the 40%.

 

[pinball1970]

Instead, it is a very practical rule-of-thumb. From the link you provided:Further on: In short: despite the poorly dressed marketing word salad in the article the original claim within its context is still true: it fails only if you take a full body ice-bath (or running around naked in the snow).

I do not plan to do any of that, ever: so I still safe to choose to accept the 40%.

Interesting, to pee or not to pee, that is the question.

Day off today and sat up at 7am naked and cold reading pf. Bathroom. 9am still reading and shivering now and I need the bathroom again.
I tend to lose track of time and external things when reading.
I assumed my body is getting rid of water via the cold / homeostatic mechanism?
A few hours later in the pub having brunch and it's a thread on pf.
I think I need the bathroom more when I am cold, this just from experience/memory.
Drinking water cools the body so micturition does the opposite? A kettle heats half a kettle faster than a full one?

 

[DaveC426913]

While their bodies were bundled up, their heads were exposed — and they were found to have lost more heat from their noggins.

Sorry, you see that as a valid objective test of the principle?

A study that concludes '...we lose a more heat through our heads then the rest of our body when our heads are exposed to frigid temps but our bodies are bundled up' is meaningful and generally applicable?

OK, then here is an equally valid conclusion:

Tests will show that if our bodies and heads are bundled up warm, but we are in bare feet, we will lose a greater percentage of heat through our feet.

And: If our bodies, heads and feet are protected but our armpits are exposed ...

You see the problem with the original test?

 

[Rive]

Sorry, you see that as a valid objective test of the principle?

Yep. That's the clothing I have while dealing with snow at winter, for example: but a good hiking at winter goes the same way, usually. Prefer having a good coat and trousers, but it is just far too inconvenient to cover my head in equivalent thickness.
I believe it goes somehow similarly in military (hence the source for the original claim). Quite important issue I would say.
That's what I call 'practical approach'.

OK, then here is an equally valid conclusion:

Guess you intended that part about feet as a joke, but feet actually is the next big issue with winter clothing right after the head. Any insulation in your boots has to bear your whole weight - and that's not a good match with the usual insulation material (air).

Those results from the 2008 report are quite like a 'mathematician's answer' by most practical means.
Absolutely correct - totally useless.

 

[DaveC426913]

Yep.

Well, it's not.

Guess you intended that part about feet as a joke...

Not as a joke: facetiously.

To point that it is absurd to
- pick an arbitrary body part,
- expose it - alone - to frigid temperatures, and then
- draw the specious conclusion that more heat is lost from that body part specifically, while
- neglecting to point out that it applies generally to any given body part.

What they've shown in the more recent experiments is simply that a given body part, when not properly protected, will lose heat disproportionately fast.

IOW, A truism.

 

[Rive]

To point that it is absurd to
- pick an arbitrary body part,

You misunderstood the starting point. It would be absurd to pick a body part randomly: however what actually happened is a check on the usual (!) clothing habits in cold conditions. Compared to that to pick circumstances which are really rare to happen (being naked, immersed in cold water) - now, that's something really absurd and won't do as an useful reference.

 

[256bits]

Interesting discussion.
Physiological response of the also body plays a part in protecting the core temperature, where blood flow to the extremities, in a general sense, is reduced in order to conserve heat. Fat content of the skin aids in heat retention. The arms, with less fat acting as insulation, become cooler, than say the thighs.
The drop in skin temperature acts in itself as an insulation by the way of less conduction due to the lesser temperature differential between the skin surface and the air.
Yet, feet and fingers do suffer frostbite, and cheeks, noses and ears, if exposed, even if there is less heat loss due to being cooler, there is also less heat production and replenishment ( less blood flow ).

I would recommend to pee in a bottle and keep the bottle close.

 

[OCR]

Physiological response of the also body. . .

Physiological response of the body also. . . ✔

Lol. . . .

 

[sysprog]

Apparently, this is an apocryphal myth.

"... the head accounts for about 7 percent of the body’s surface area, and the heat loss is fairly proportional to the amount of skin that’s showing.

At most, according to a 2008 report in BMJ, a person loses 7 percent to 10 percent of their body heat through their head..."

https://www.livescience.com/34411-body-heat-loss-head.html

Brain is disproportionately-favorably blood-supplied compared to other somatic components.

 

[sysprog]

Summary: Should I pee or hold it to stay warm?

Summary: Should I pee or hold it to stay warm?

This was on TV many years ago several people were lost in freezing cold weather. One person needed to pee but another person said no hold it as long as you can it keeps you warm. Another person insisted your body generates a fixed about of BTUs of heat it is better to pee to reduce your body mass this will keep you warmer.

Which will keep you warmer, pee or hold it?

Well, it's not especially optional -- bladder urgency must be addressed -- so dump the bladder contents, but not on your body -- and build a fire and get it started and warming you -- and please survive.

 

[pinball1970]

Interesting discussion.

I would recommend to pee in a bottle and keep the bottle close.

Clever, one way to lose water and retain some of the heat.
Cells produce heat, this heats water in the body, urine, blood lymph digestive juices, mucosal secretions etc. Lose water therefore slightly less to heat.
In extreme conditions hikers check the colour of urine to make sure they are not dehydrated. I have never been in extreme cold conditions for a long time but I am assumin the temperature responses are overriding the thirst response?
The body does not want to freeze to death first, before considering rehydration?

 

[sysprog]

Clever, one way to lose water and retain some of the heat.
Cells produce heat, this heats water in the body, urine, blood lymph digestive juices, mucosal secretions etc. Lose water therefore slightly less to heat.
In extreme conditions hikers check the colour of urine to make sure they are not dehydrated. I have never been in extreme cold conditions for a long time but I am assumin the temperature responses are overriding the thirst response?
The body does not want to freeze to death first, before considering rehydration?

Right -- you want a stick or other weapon to fend off the wolves. If the content of the water bottle hasn't already frozen, then it's warm enough in the Great Outdoors, and you're being too much of a sissy if you worry, and if you're in snow-land there's frozen water so you won't die of thirst --

And no, the loss of the tiny amount of energy that a person loses by taking a leak is not going to be what is written on the certificate as the cause of death.

I once read of guy who was in the Klondike in extremely cold weather, and he took a flask of liquor from his pack, and drank a gulp from it, having forgotten than even though the flask contents were liquid enough, they weren't anywhere near close to warm enough to drink, and shortly after he was rescued, he was treated for frostbite in the upper area of his alimentary canal . . .

 

[256bits]

Clever, one way to lose water and retain some of the heat.
Cells produce heat, this heats water in the body, urine, blood lymph digestive juices, mucosal secretions etc. Lose water therefore slightly less to heat.
In extreme conditions hikers check the colour of urine to make sure they are not dehydrated. I have never been in extreme cold conditions for a long time but I am assumin the temperature responses are overriding the thirst response?
The body does not want to freeze to death first, before considering rehydration?

cold-induced diuresis - you may end up having to pee more by being cold than by being comfortable. One can actually dehydrate in cold weather as you mentioned about the hikers.
Let these guys explain.
http://www.arkansasurology.com/blog/what-is-cold-diuresis

 

[DaveC426913]

Brain is disproportionately-favorably blood-supplied compared to other somatic components.

While true, it does not apply - the experimental evidence indicates that, subjected to similar conditions, the head loses a similar amount heat per unit skin area as other parts of the body.

 

[sysprog]

While true, it does not apply - the experimental evidence indicates that, subjected to similar conditions, the head loses a similar amount heat per unit skin area as other parts of the body.

I imagine that gloves and shoes make more difference regarding heat loss per gram, but hands and feet aren't as massive as heads -- I'm a light-complected alopecia-pattern-bald guy -- usually I wear a ball cap in summer for shade, and a watchcap in winter to fend off cold -- I was a bit skeptical, regarding the number, when I was told that if you don't wear a hat, 40% of the heat you'll lose, when otherwise dressed for cold, will be from your head, but I didn't then and don't now dismiss the value of wearing a hat.

 

[Vanadium 50]

After reading this thread, I can no longer hear the Clash's "Should I Stay or Should I Go?" without thinking about it.

 

[marcusl]

Keep in mind that your body reduces circulation to the "extremities" (that's arms and legs) when cold in order to reserve heat for your core organs. That, coupled with the large ratio of surface area to volume, is why frostbitten fingers and toes are so common. Heat flux from extremities is lower than from torso and head, giving some support to the proportion of body heat lost from the head in the cold.

 

[Jacinta]

I'd imagine if you were lost you'd hold your pee in not because it'll keep you warm but it'll dehydrate you if you pee and you have no access to water.

 

[WWGD]

I'd imagine if you were lost you'd hold your pee in not because it'll keep you warm but it'll dehydrate you if you pee and you have no access to water.

I have seen some e.g. survivalist Bear Grylls (sp?) even suggest under certain conditions one drink the pee to hydrate or lower risk of dehydration.

 

[BillTre]

it'll dehydrate you if you pee and you have no access to water.

Actually, once urine is in the bladder, I don't think there is much water re-uptake of water from the urine. That's what the kidney is made for. However, the kidney is upstream of the bladder which stores and accumulates the kidney output.
The urine in the bladder is already separate from the other fluids of the body (within which dehydration would have its effects on overall health).
Kidney function can be controlled by normal and diseased bodily functions, as well as medicine (I assume).
Over longer terms than just having to go pee, effecting these control mechanisms might either produce or prevent dehydration.

 

[DaveC426913]

Agree with Bill. I don't think holding your pee will mitigate dehdyration.

On the other hand,
1] the muscle effort to hold in your pee will burn calories unnecessarily.
2] the risk of accidentally wetting yourself increases greatly - and that can have lethal consequences in a frigid survival situation.

 

[gary350]

Interesting, to pee or not to pee, that is the question.
A kettle heats half a kettle faster than a full one?

If both kettles are 98 degrees, a kettle still heats half a kettle faster than a full one.
When I was young I had hair I never wear a hat. Now I have no hair and always wear a hat.

 

[DaveC426913]

If both kettles are 98 degrees, a kettle still heats half a kettle faster than a full one.

That is an inapplicable analogy to retaining body heat.

 

[Rive]

Over longer terms than just having to go pee, effecting these control mechanisms might either produce or prevent dehydration.

For example coffe or alcohol (any form). Worth mentioning that the short warm feeling from alcohol in cold might have a high price in severe conditions: both in dehydration and in losing 'core' heat in increased rate - since alcohol does not produces heat, but helps to lose it (by warming up your skin).

if you're in snow-land there's frozen water so you won't die of thirst --

'Drinking' ice also comes at the price of lot of lost 'core' heat. The amount of heat required to melt ice is no joke. So while the 'pee or not' will not matter directly, 'drink or not' does in case you have only something cold to drink.

I have seen some e.g. survivalist Bear Grylls (sp?) even suggest under certain conditions one drink the pee to hydrate or lower risk of dehydration.

Urine usually has a relatively high salt concentration. Drinking salted water in survival situation - in general, that's a very bad idea.

 

[DaveC426913]

'Drinking' ice also comes at the price of lot of lost 'core' heat. The amount of heat required to melt ice is no joke. So while the 'pee or not' will not matter directly, 'drink or not' does in case you have only something cold to drink.

Yes. It's a balancing act, dependent on circumstances. But there's little point in keeping warm if dehydration results in your being unable to care for your survival needs.

Urine usually has a relatively high salt concentration. Drinking salted water in survival situation - in general, that's a very bad idea.

In long term, yes. Like at sea. But again, an immediate threat of dehydration (and resultant loss of faculties required to survive) might be more immediate than longer term problems with drinking urine.

For example, rehydrating with urine may give to the ability to get to better shelter or build a fire, whereupon, you can then get fresh water at your leisure.

 

[neanderthalphysics]

One way of looking at it, is when you pee, you increase the surface area of your "body (+ pee)" and therefore increase the rate of heat loss.

 

[gary350]

Assume a person weighs 200 lbs the average person pees about 6 oz. 3200 oz vs 6 oz pee is .1875% of your body weight. Assume your lost in the wilderness in freezing weather 6 ounces of 98 degree liquid probably won't keep you alive more that several extra minutes.

 

[WWGD]

Ultimately it may be more useful to determine the factors that have the largest weight over the outcome( survival). I doubt there have been many cases where someone died because they decided to pee. To paraphrase someone in this post ( I think it was @pinball1970 ), to pee or not to pee is not the question. Edit: Maybe we should look into those final 10 to complete a 360 , Gary ;).

 

[pinball1970]

One way of looking at it, is when you pee, you increase the surface area of your "body (+ pee)" and therefore increase the rate of heat loss.

Lots of ways of looking at this and from a biological/physics point of view I think this has been illustrated in the posts.
One last thought from me, retaining urine gives increase risk of cystitis. As per @DaveC426913 just let it go, stress of retaining probably out weighs some of the very slight thermodynamics advantages.
More importantly I honestly thought my Hamlet quote would have got at least one tip of the hat. That was mildly clever and also slightly funny. Slightly.

 

[WWGD]

Lots of ways of looking at this and from a biological/physics point of view I think this has been illustrated in the posts.
One last thought from me, retaining urine gives increase risk of cystitis. As per @DaveC426913 just let it go, stress of retaining probably out weighs some of the very slight thermodynamics advantages.
More importantly I honestly thought my Hamlet quote would have got at least one tip of the hat. That was mildly clever and also slightly funny. Slightly.

Us nerds don't always have time for fun, Pinball.

 

[pinball1970]

Us nerds don't always have time for fun, Pinball.

There is a sliding scale, I put @PeterDonis @Dale @Vanadium 50 at the more serious end and the likes of @phinds @berkeman @DaveC426913 @DennisN at the other. Unless someone posts something stupid, unverified or personal theory without searching then everyone on here can go full terminator mode.

 

[Andrew Mason]

Which will keep you warmer, pee or hold it?

I would suggest that you do both if you have a water tight container like a plastic bag. Pee into a plastic bag and hold it just under the outer layer of your clothing or your coat but not next to your body until it freezes completely. Each millilitre of urine will release about 490 Joules of heat energy into the air space between you and the outside air as it cools and freezes.

AM

 

[sophiecentaur]

recent studies attempted to reproduce the effect and concluded that, per unit skin surface, heat loss via the head was no more than anywhere else on the body.

I am always alerted by the word "studies". They can vary in integrity and according to the original ideas of the 'studier'. Would a fair test involve naked bodies, arctic explorers, divers or people standing at a bus stop in winter?
People with any sense do not go out in cold conditions without good head gear so the 40% figure is a good frightener to encourage wearing the right clothes, even if it is a bit approximate.
When I am poorly in winter, I often wear a woolly hat in bed and that makes me feel a lot less bad.

 

[Baluncore]

Over longer terms than just having to go pee, effecting these control mechanisms might either produce or prevent dehydration.

Agree with Bill. I don't think holding your pee will mitigate dehdyration.

I do expect back pressure from the bladder on your kidney ion exchange membranes will reduce the volume of urine produced. That may be important if it reduces the rate at which you must eat snow to rehydrate.

When I am poorly in winter, I often wear a woolly hat in bed and that makes me feel a lot less bad.

When sleeping in the cold, put on a hat, but also take off your socks. That either reduces blood flow restriction in your feet, or reduces peripheral heat loss. Feeling cold is a feeling, it is more important to retain core warmth. The final response to hypothermia is feeling hot and stripping off clothing.

 

[sophiecentaur]

but also take off your socks.

I think the philosophy of bed socks is that they are deliberately over sized so you get the benefit of insulation without strangulation. I get cold feet in bed and in winter, the big loose socks are just brilliant. My temperature regulation is really rubbish and I 'feel' hot or cold long before the other people with me. (In bed, that's just a single person Lol)

 

[DaveC426913]

People with any sense do not go out in cold conditions without good head gear so the 40% figure is a good frightener to encourage wearing the right clothes, even if it is a bit approximate.

That's a very different argument.
That's not a scientific view, that's political view - an attempt to sway others' understandings away from facts and toward what you think they need to hear.

Why not just make it 100%? It's a slippery slope you choose to walk.


Other examples: