system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If food gives us energy why do we get tired after a big meal?

Edit: Thanks for the answers!
gpt
Different definitions of "energy".

Food provides chemicals that your body needs to support its metabolism.

Feeling tired has no relation to whether or not your body has what it needs to function (except in extreme cases of starvation), but is instead a result of brain activity.

In short, "feeling energetic" is not caused by having chemical energy available for your body to use.