The path to healthy food isn't in telling kids what to do, but exposing them to something better. Look at what Japanese kids eat. I _know_ kids would prefer salmon-roe onigiri and fried rice to potato chips and twinkies.
(I think this is a good thing if, and only if, the food is healthy and worthwhile to eat - as here. It's easy to rail against branding and advertising - it's harder to prove it doesn't work.)
Just look at photos of what the Jap kids eat for lunch:
This is actually what they eat for lunch everyday. It's amazing.