DC are grumpy because we don't allow random grazing and ask that they let me know when they're planning to prepare food using high-value ingredients or ingredients which may reasonably form a central component of a family meal.
I buy enough packed lunch items to last them both for the week, and much prefer it if I don't have to buy replacements if someone eats extra bags of crisps or snacks on extra packets of raisins or grain bars or similar.
Ditto preparing snacks between mealtimes: making toast, or bowls of pasta or cereal, or making fruit smoothies, or baking cupcakes.
Mine will get bowls of frozen peas or sweetcorn to snack on, so I often open the freezer to find empty bags.
Or unlimited condiments, for that matter -oodles of ketchup, sweet chilli sauce or mayo etc.
Or raiding the fruit bowl; there's enough fruit for everyone to have a couple of pieces per day but not to eat 3 bananas in a day, for instance.
We eat 3 square meals a day; quality home-cooked / prepared food and always have fruit available, so they're not going hungry. DC1 in particular insists that all their friends have free reins in the kitchen and that their cupboards are stuffed to the gunnels with snacky foods to which they help themselves with gay abandon, citing fridge raids of quantities of items I could never sustain in our home on our budget: I literally couldn't afford to stock lots of grazing foods in case someone feels a bit bored or peckish.
Can you, and do you, keep plentiful reserves of snacks which your DC are allowed to help themselves to?