Overseas flights pretty much serve you enough food to stave off the grumbles. However, when you think of some flights being 4 hours or longer without any food being served at all, or having to pay for food on your flight, you may want to bring your own snacks on board.
It is hard to find healthier options on board flights so I usually resort to packing my own snacks. Many of the items don't require refrigeration so you can also create your inflight menu of items from your vacation location as well. I do tote it all in a small, soft-sided cooler bag so that I have everything in one place.
I am including what I usually pack to bring on board for a 3-5 hour flight, and have tried to include kid-friendly snacks.
Plan what you will need for your snacks, including disposable containers, and an empty water bottle. You can ask for napkins on board, but I steer away from items that require cutlery.