candy is the root of all evil

My son has determined that the only item of sustenance that man needs for survival is candy. All other food - healthy or otherwise - is unnecessary. Admittedly, my wife and I have let him slide down this path unchecked for too long, but we both swear that 2010 represents a new day. The little guy and his sister have wretched eating habits, and that needs to change. Do we start by just removing the bad stuff? Do we focus on introducing new things? Do we merely emphasize the good things that they're already - partially - eating? I'm not sure what the best course of action should be, but 2010 promises to be the year where we at least begin to find out!