Our bodies are on average 98.6°, right? Why do we sweat profusely and dislike hot temperatures? Wouldn’t our bodies have to work less and use less energy to keep an internal temperature of 98.6°?
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Your skin temp is considerably lower than 98.6 degrees. If the air is the same heat as your body temp, your body has no way to cool itself by transferring heat to the air via sweat and exhaling warm air
We are constantly generating and shedding heat to maintain 98ish.
When the ambient temperature is at or above 98, it becomes much more difficult for us to shed heat to maintain 98. If your body doesn’t do anything about it, heat will start to build up in the body. Especially because that’s an internal temp, your skin is cooler so you start struggling to radiate away heat even lower than 98, but most people really start to struggle somewhere in that 98-100 zone.
The more difficult it is to shed, the more your body does to try and shed it. Sweating, changes in respiration to get more heat out that way, changes in circulation, maybe getting a little lethargic to try and slow down how much heat is generated in the first place.
This is also why things like wind, humidity and shade makes such a difference to how a given bient temperature feels. Water in the air changes the rate of heat exchange and how effective sweat is. Wind improves the shedding rate and helps evaporate sweat. Direct sun adds heat on top of what is in the air directly to your skin. All that stuff.
>Wouldn’t our bodies have to work less and use less energy to keep an internal temperature of 98.6°?
Hypothetically, but there’s a minimum amount of heat that you have to generate in order to be alive. The biological processes keeping you alive are exothermic, thus the only way to *stop* that heat from being generated is to stop the processes, i.e. to be dead.
Thus, the ideal ambient temperature is the one where your body’s natural energy consumption is minimized *and* all of the heat you generate can be conducted away from you. That temperature is roughly 70F.
For the most part, your body does not use energy in order to keep up its temperature. Your body uses energy in order to move muscles, to transfer nerve signals, or to convert nutrients into the kind of molecules that make up your body. Most of that energy ultimately ends up as waste heat, and that waste heat has to go somewhere, as your body would otherwise boil itself within a few hours. Those 2000kcal you’re eating every day? That’s – by definition – enough energy to heat 2000 kilograms of water by 1.8°F (1°C), or 50kg (roughly the amount of water in an adult human body) by 72°F (40°C), to a total of 170°F (77°C). According to [this chart](https://www.chefstemp.com/pork-temperature-chart/), and assuming human meat behaves similarly to pork, you’re now slightly beyond “well done”.
In order to avoid becoming a rather chewy piece of long pork, you need to lose that heat somehow. The easiest way is to exist in an environment that is slightly cooler than your body temperature, so you are constantly losing heat to the environment, which is why people feel most comfortable at temperatures around 22°C (70°F).
The metabolic processes that occur within the human body, when working properly, produce heat. About 98F. However, those processes work best at lower ambient temperatures, like 72F.
Imagine you’re using your computer. Put your hand in front of the fan. It’s probably blowing out air that is warmer than the ambient temperature because the machinery within the computer produces heat. The computer may be blasting air that’s 90F, but the computer would not work as well if the ambient temperature was 90F because the machinery within works best at low temperatures. If the ambient temperature was 90F then the computer would overheat.
Whenever we do anything (walk, talk, breathe, digest food, think), it uses up energy. Whenever energy gets used up, some gets wasted and turned into heat. For our bodies to stay at any given temperature, we need to be generating the amount of heat equal to the heat we lose to the environment around us.
The bigger the temperature difference between two things, the quicker heat flows from the hot thing to the cold thing. If it’s cold outside, our bodies lose too much heat and cool down quickly. To compensate, we make more heat, for example through shivering (basically a lot of small muscle movements designed to “waste” lots of energy).
On the other hand, if the air is the same as our body temperature, or even hotter, we don’t naturally lose any heat. In fact, if it’s hotter outside than we are, we’d be *gaining* heat. In either case, it’s a problem because we’re still *generating* heat through wasted energy.
And, there’s no easy way to make something cooler. Fridges and freezers work by taking the heat from inside them and pumping it outside, which is a really inefficient process. The best we can do is try to not use as much energy (so we feel really tired), take in cold stuff (like water) that can absorb some of our heat, and sweat lots because evaporation will cool what’s nearby.
We burn hotter than 98.6, but stay that temperature cause it is constantly leaving our body. If the outside temp is hot, less heat will leave our bodies as easily.
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