system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When you're sick, why does your appetite often go away?

 I've noticed that with certain sicknesses, I tend to go most of the day without eating anything; if not all day. Usually just for one day though, then I get my appetite back. Normally (when I'm not sick) if I go a few hours without eating I get "hangry". I'm used to eating quite a lot throughout the day though because I have a fast metabolism. So (for me it happens with tonsillitis or stomach bugs) why is it that when you're sick you don't feel inclined to eat? Doesn't your body need food for energy to fight the sickness? And why does it seem that only certain sicknesses suppress the appetite?
gpt
attrition. In a bacterial infection, your body pumps out different hormones to fight it, one of these lowers your glucose levels, which is what the bacteria eat, so your body is trying to starve it out.