Understand how your body loses heat | Squat the Planet

Understand how your body loses heat

Tony Pro

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Who doth ambition shun
And loves to live in the sun,
Seeking the food he eats,
And pleased with what he gets,
Come hither, come hither, come hither:
Here shall he see
No enemy
But winter and rough weather.

-Shakespeare, "As You Like It"

Winter is setting in where I am. One of the lessons I remember my mom teaching me during backpacking trips as a kid are the 4 ways the body loses heat. Over the past two weeks I've been sleeping rough without a tent or sleeping bag so I've had occasion to reflect on each of these principles. It occurred to me to start a discussion about them in case anyone didn't know about them and could benefit from them. Some of these ideas seem obvious (cold wind makes you cold, no shit) but it can be helpful to re-frame the way you think about why you're cold.

The 4 ways the body loses heat:

-Evaporation
The principal way the body releases excess heat is through sweat. The reason this is so effective is because water conducts heat much better than air. This is why moisture is good when you're too hot -- but very bad when you're cold.
What this means for hobos: Stay dry at all costs. Try not to get sweaty if you're walking in the cold, because as soon as you stop moving you'll start to freeze. Don't let wet stuff contaminate other gear with dampness. My mother used to say it's better to sleep naked than to sleep in wet clothes. Set aside time during the day to get all the wet shit out of your bag to dry.

-Radiation
This is the simple process of heat emanating from a warm object like a woodstove or a hotcake. In cold conditions, this is how you lose most of your heat.
What this means for hobos: Bundle up of course! You lose a disproportionate amount of heat through your head [edit: possibly bullshit; see comment below], so wear a hat. Don't neglect your legs either; I don't care how puffy your coat is if you don't have any longjohns on under your ripped jeans.

-Conduction
This is actually the same principle that sweating is based on: sweat conducts heat away from the body, but so does anything else close to you, such as cold ground, or your girlfriend's cold feet. This is also why sleeping next to another warm human is the best way to stay cozy.
What this means for hobos: Don't go sleeping on the bare ground and wondering why you're cold at night. If you don't have a sleeping pad, put anything under you -- cardboard, clothes, a hammock, a trash bag stuffed with dry leaves.

-Convection
Moving air robs you of heat, whether it's cold wind or an electric fan.
What this means for hobos: Take advantage of any kind of shelter possible. Think about wind direction while picking a campsite. A tent makes a surprising difference in holding a bubble of warm air around you. If you have no tent, throw a windbreaker, space blanket, or tarp over yourself (but be careful as these can trap perspiration and get you wet).

Like I said, it all seems obvious but this is one of the first lessons they teach you in survival training for a reason. You can mitigate cold more effectively if you track down the precise cause.
A shoutout to all brothers sleeping rough tonight. As you shiver, I shiver with you.
 
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Tony Pro

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Keeping warm

This is where I drop all pretense of expertise; I just want to share some things which I think are important based on my own experience. In circumstances when your body is your only source of warmth, it pays to be conscious of how your body is producing heat and how you can help it do its job.

-Eat a lot...or don't
Your body's metabolic processes are what produces heat, and that's run off of the burning of calories from food. But annoyingly, eating food will make you feel colder in the short term because blood is taken away from your extremities and sent to your gut. So if I'm hitchhiking in the cold with my naked thumb stuck out, I avoid eating for comfort's sake. But when it comes to actually keeping your core temperature up, your body needs that food. Before going to sleep I make sure to stuff my face. 'Empty' calories are good for this purpose, as you only need them to tide you over through the night. White bread from the dumpster, sugar packets from Circle K, ketchup packets from McDonalds...don't hold back; the more you eat the warmer you'll be. Just be sure to brush your tooth.

-Alcohol doesn't really make you warm
As with food, this is a comfort vs. reality choice based on circumstances. Alcohol absolutely will lower your core temperature. It makes you feel warm by bringing more blood to the surface of your skin (exactly the opposite of why food makes you feel cold), but what this is ultimately doing is exposing your warm blood to the cold air. It also slows some metabolic processes, and makes you less likely to shiver.
However, if you don't think there's actual danger of hypothermia, and comfort is your priority, drink up.

-You shiver for a reason
I didn't realize this until I read how the old fisherman from Hemingway's story "was shivering with the morning cold. But he knew he would shiver himself warm..." For some reason people tend to fight the reflex to shiver or chatter, but it's the body's way of giving juice to the metabolism while you're sitting still. Loosen your muscles and shiver yourself warm. If you don't want to wave your arms, or even get up and dance, you can tightly flex and then relax your muscles over and over again; this burns more energy than shivering and achieves the same effect.
 

Dameon

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What this means for hobos: Bundle up of course! You lose a disproportionate amount of heat through your head, so wear a hat.
That's actually an old wive's tale, and all you have to do to see it's not true is look at a thermal heat-map of the human body. You lose more or less as much heat through your head as you do through the rest of your body. I am a fan of hats, though, personally.
 
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Desperado Deluxe

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One thing I figured out was to actually breath cold air to acclamate your body more to the outside temps instead of covering your face too much and recirculating your breath.

For me having a way to heat up food in freezing temps is pretty ideal. And another trick I've used a lot recently is getting a glass bottle and filling it with hot water or coffee right before bed. I'll keep it in my sleeping bag under my back or legs which really helps keep you blood moving and warm for about four hours.

Best sleeping thing is a tarp period. Keeps the wind off and traps heat. You can always pile up those dead leaves and such underneath it for padding. Way better than a tent for the size, weight, and price ratios.
 
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MFB

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Keeping warm

This is where I drop all pretense of expertise; I just want to share some things which I think are important based on my own experience. In circumstances when your body is your only source of warmth, it pays to be conscious of how your body is producing heat and how you can help it do its job.

-Eat a lot...or don't
Your body's metabolic processes are what produces heat, and that's run off of the burning of calories from food. But annoyingly, eating food will make you feel colder in the short term because blood is taken away from your extremities and sent to your gut. So if I'm hitchhiking in the cold with my naked thumb stuck out, I avoid eating for comfort's sake. But when it comes to actually keeping your core temperature up, your body needs that food. Before going to sleep I make sure to stuff my face. 'Empty' calories are good for this purpose, as you only need them to tide you over through the night. White bread from the dumpster, sugar packets from Circle K, ketchup packets from McDonalds...don't hold back; the more you eat the warmer you'll be. Just be sure to brush your tooth.

-Alcohol doesn't really make you warm
As with food, this is a comfort vs. reality choice based on circumstances. Alcohol absolutely will lower your core temperature. It makes you feel warm by bringing more blood to the surface of your skin (exactly the opposite of why food makes you feel cold), but what this is ultimately doing is exposing your warm blood to the cold air. It also slows some metabolic processes, and makes you less likely to shiver.
However, if you don't think there's actual danger of hypothermia, and comfort is your priority, drink up.

-You shiver for a reason
I didn't realize this until I read how the old fisherman from Hemingway's story "was shivering with the morning cold. But he knew he would shiver himself warm..." For some reason people tend to fight the reflex to shiver or chatter, but it's the body's way of giving juice to the metabolism while you're sitting still. Loosen your muscles and shiver yourself warm. If you don't want to wave your arms, or even get up and dance, you can tightly flex and then relax your muscles over and over again; this burns more energy than shivering and achieves the same effect.

10 nerd points for working A Hemingway quote into this post! 😊
 
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