I didn't want to make it too unusual in terms of regularity, so I got some rough ideas of what sort of caloric intake it'd take, and then threw most of the realism out the window for the sake of more pleasant fantasy rules. In terms of regularity, Mimi eats as often as anyone else. In terms of amount, however, it's quite a lot. To sustain her size, her muscle mass, and the endless well of sizey energy within her, the actual amount of food for her appetite is quite substantial. Consider your typical Monster Hunter: World meal scaled up to her.