Growing up, I had to ask for food and didn't mind being told no. (Although I was anorexic in my teens, so being forced to eat up to one meal a day wasn't appreciated.) DH was only allowed bread and jam as a snack - MiL complained a few times to me years after the fact he'd go through a whole loaf of bread in an evening!

Liebs is allowed to help himself to fruit, as I buy in cheap fruit for him to snaffle. Everything else he has to ask. Because I can't just pop to the shops the next day and if he eats tomorrow's lunch then I'm pretty much stuffed for his lunchbox.