Have you ever tried eating as much as you can?

[They don't get full. They don't get full no matter how much food they've put away; Hakkai hasn't yet extended the experiment far enough to talk one of his shinki into weighing himself after eating known weights of food, but he suspects it wouldn't make too much of a difference. And that's putting aside entirely the awkward fact that neither shinki nor gods seem to engage in normal digestive processes.]

We can't walk through walls, but we're not normal physical beings, either.