I know what you mean, mine have settled down a bit now.
On a normal school day they’d have breakfast at home (cereal and fruit), then just after registration they have access to bagels (a free snack the school provides to ensure all the kids have eaten), then they have break time about 10:30 and a snack which they take in or buy. Lunch at 12:00 (always 2 courses). Quick snack in afternoon break and then home, where they complain about how hungry they are until tea time (about 17:00).
My lad is very active and naturally quite skinny. The daughter is not so lucky and has put some pounds on. We’ve had to cut right back on snacks and sweets to get then shed again.