I've had a thought recently (blows fanfare):

EVERY DAY at nursery DS has sandwiches with white bread for his tea. He has a cooked meal at lunch, but his 4pm tea is juice, ham/cheese sandwiches (he has 6-8 quarters usually and demands more if he can), strips of fruit/veg (eg cucumber, carrots) and some tomatoes, followed off by a jam tart or an apple pie... the sort you get from the supermarket in a box.

He has this in balance with a breakfast of weetabix and toast, fruity snacks in the morning, big cooked lunch... he's healthy. (I cook a dinner every night at 6 too for him.)

He also refuses fast food, we had to do a motorway dinner at the weekend and he wouldn't eat a thing, so his dinner was ricecakes, sultanas, grapes, apple and apricot (after a lunch of tuna and sweetcorn sandwich and toddler biscuits - out and about far from home day). I made everyone else change his nappies the following day! Too much fruit and veg is toxic.

If your diet is fairly healthy you can miss a day of perfect food. If you get only four fruit-and-veg a day, that's better than none or one most days and a big cram-it-in of ten once a week. Just don't ignore the good food when it's available.