I didn't have kids when I went either! joking appart, taking a few snacks wouldn't do any harm, that way you get to spend your money on what you want to rather than wasting it on bags of crisps.
Just found this site for disneyland that has some info on therestaurant there and if you click on the restaurant, and then on menu, it gives you an idea of the prices - looks fairly reasonable, and so I would imagine that outside the parc it is likely to be cheaper.
http://www.dlpfoodguide.com/magickingdom.html