system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 : When you get cold what stops our body from just heating itself up like when we are sick?

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.
gpt
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.