Why diet for kids? If you are talking about a obese child, then fine. Otherwise you just need to get rid of all the junkies from your house, cut down on the frequency of outings at pizza huts and Mac Donalds etc. Instead opt for fresh fruits, and juices, decorate them with fancy stuff, make the child's food dish decorative and colorful and you can make the pizza's and burgers at home too by including all the vegetables you have.