How do I make it not awkward?

So I babysit two kids, a three year old and a almost 2 year old. I have a almost two year old myself.

Anyway, I’m not so sure what their parents give them for breakfast but they come suuuuuper hungry and ask for “snacks” right away like even before their parents leave the door? The earlier they come like (6:20) they get hungrier faster and burn right through their snacks. It’s usually just packaged mini muffins, cheez it’s, or cookies everyday. With occasional fruit but they always ask for more. Always more. I sometimes give them what we have but it’s hard because they don’t pay me to feed them...and we don’t budget for their kids when we grocery shop. For breakfast I’ll usually give my son a waffle with fruit or fairly balanced meals with fruit as snacks. So I feel bad 😕 How do I ask without making it awkward?