So this isn't my own head cannon but I wanted to add it. I can't remember where I saw it but if I find it I'll credit.

Akaashi has abusive parents and they're super strict with what he does and how much he eats and shit. In the barbecue arc he was eating and people say he eats a lot so that's where it stemmed from I'm guessing.

Sorry I don't post often. Working on a Seto x Reader that I'll hopefully post soon.