I know people can get fevers up to +100f/37c. So why can’t our body just flip a switch and turn on a fever essentially. I have plenty of “stored” energy so I don’t see how that would be a problem.
In: Biology
During WWII the Russians would give some chemical compound to soldiers during the winter months which makes their body burn hot to keep them warm.
I think bodybuilders still use it today to burn off that extra fat before a competition. Accounts of people who take it make it sound like it’s horrible; like Flu like symptoms.
Edit: I think it’s called Dinitrophenol
Getting your temperature up in a warm environment over hours is easy: a low net heat output increases temperature over time to pretty high. Keeping it up in freezing temperatures is hard because the body loses the heat so fast.
Your body is actually very good at keeping you warm enough under a very wide range of temperatures. As with everything with humans, if you want it to be better at it, you can “practice” by progressively doing things that make you chilly. If you are active, you can last pretty much indefinitely in a t shirt and shorts in above freezing temperatures. Just go in/warm up when you start to shiver: that means your body isn’t keeping up with your core temperature. Eventually, you wont ever start to shiver. Source: I went year round in T shirt and shorts in freezing/close to freezing temperatures while being outside for hours at a time.
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It tries, but you are leaking heat far faster than your body’s ability to produce it. The problem isn’t heat production; it’s heat loss. There’s a reason why people used to put people with high fevers in an ice bath. That reason is because it works.
When you get sick, the thermostat in your body is increased from 98.6F to >100F. This is caused by whatever is making you ill. When you are feeling cold, instead of turning the thermostat up, it tells your body to shiver and constrict blood vessels to keep heat in.
The reason why you don’t want that thermostat being turned up when you’re just feeling cold is because getting too hot is bad. Too much heat breaks things down that shouldn’t be broken down. That’s why there are other mechanisms for your body to warm itself up.
To add context to the top answers – the reason why your body is more interested in conserving heat than it is in heating up is that most of your bodily processes will continue if you’re cold, and it takes a ton of energy (comparatively) to pump up the thermostat.
All of your body’s various nervous system functionalities are geared for survival. Survival is massively dependent on energy use. Your body manages its calories very carefully, and has a lot of mechanisms in place to store and hold onto calories. It’s why we get fat, and it’s why our ancestors were able to run down prey much larger than ourselves without tiring. Creation of heat takes a relative ton of calories – your body naturally creates some heat as a byproduct of your energy cycle, but creating more incurs an expensive calorie cost.
Actual regulation of bodily temperature is an important concept to survival – all of the proteins you have in your body are finely-tuned to work at 37°C/98.6°F. If your body goes appreciably above that, the proteins begin to denature (unravel) and lose functionality. When your body detects an immune response, it decides that the high calorie cost and potential protein/cellular damage is likely worth it to fight off the infection. This is why you feel like shit when you run a fever – your bodily processes aren’t working as efficiently. You’re sore (muscles are not as effectively repairing themselves / carting away metabolic byproducts as quickly), fatigued (less energy available because you’re running your internal furnace trying to burn out the infection), and with extreme fevers you’re probably delirious (actual damage to brain tissue caused by extreme fever denaturing proteins necessary for your brain to function).
So the question and answer with greater context, now; why doesn’t your body just turn up the thermostat when you’re feeling cold? Because between creating more heat and conserving the heat you already have, conservation is the one that will keep you alive longer per calorie spent. Vasoconstriction is the body’s method of triage when dealing with cold; check out your fingers next time they’re really cold, and you’ll notice that they are lighter in color. This is because the tissue in them has received a neural response to tightly clamp down on blood vessels, which lessens heat loss due to your blood circulating through that area. The concept is that less warm blood flowing out to your extremities, cooling, and then flowing back to your core to lower your core body temperature will keep you alive the longest at the lowest calorie count. Conserving the heat costs way less calories than making more of it. If instead you tried to keep the whole body warm all the time by producing more heat, you’d be dead way earlier due to radiating the heat away and having to keep producing more.
It’s 100% about survival. Your parasympathetic nervous system doesn’t know the difference between the A/C being up too high and you being stranded in the middle of a frozen tundra. It acts accordingly.
Edited to put more emphasis on the fact that it’s more expensive to produce more heat relative to conserving it. The overall goal is to maximize time survived per calorie.
It requires energy, the body doesn’t like to waste energy, it also is damaging to the body so it only happens when the body is seriously at risk.
A lot of people have addressed the immune system part of rising your core temperature to fight off an infection but I don’t see anyone addressing the sensory part. Your core body temperature can stay at 98.6 and you can feel cold. The sensory of cold on your outer layers is a mechanism to warn you of rapid heat loss in certain areas. Your body will increase the heat output to fight the heat loss but just because your hands/feet/face or whatever makes you feel cold, doesn’t mean that your actual core temperature is affected. These are really just signals. Like pain. Pain is a warning for potential damage, the same is true about feeling cold. Don’t think of feelings as status effects, think of them more as warning messages.
On the immune side, think of your core temperature rising(fever) as though its killing the problem with fire. If you were growing plants but they got too cold at night, would you set them on fire? No. You would either move them to a warmer place or cover them. The body isn’t going to treat every sensory issue by killing it with fire. It’s doing it as a last natural resort. Without modern medicine, if the fever didn’t kill it, you died.
I think I can explain this in ELI5 style.
Your body is trying to lose heat slower, so it reduces bloodflow to the extremities. Your body works it’s damnedest to warm your innards, like your heart, brain, etc., Focusing it’s attention in the most important organs for as long as possible to keep you alive. Your body doesn’t know how long it will be in the cold, so it goes into survival mode.
Interestingly, alcahol can make you ‘feel’ warm, because it increases bloodflow to your extremities. This feels nice for a short spurt in the cold, but it will kill you much faster.
The body can do that – we have brown adipose tissue meant specifically for that. The problem is, it doesn’t really work well in modern people, because we rarely get exposed to cold temperatures anymore.
Essentially, what Wim Hof does is comepletely normal, and more or less anybody should be able to do it with some regular cold exposure and enough food to eat.
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