I agree, best to lead by example and explain why we need to eat healthily. Don't do a blanket ban on anything considered to be unhealthy, this tends to increase the craving. I get mine to try everything that is on their plate. Even just a tiny taste. If they do not like something that is fine but they do not get an alternative. Persevere, my kids have all disliked things at various stages but by getting them to try each time I serve something they have developed their taste for new things. My six year old loves salad, asks for fresh veg and fruit, asks for brown bread and understands healthy eating and the need for exercise. Having said that my four year old does eat the above but not strictly by choice LOL. If they are really reluctant you can hide loads of veg. in a home made pasta/rice sauce by blending it. Then after they have cleaned their plates let them know what they have just eaten. It gets them thinking if nothing else. Now I may be a control freak but my kids are not allowed to help themselves, fridge and cupboards are out of bounds unless I have specifically said they can get something ! This has always been the rule for us so isn't an issue but I know it can be sometimes. Just a few hints that have worked for us.