Once you clean your body out, there's strong motivation to avoid putting unclean things in for sure, but there's still social situations you need to learn to deal with, emotional eating if that's something you do, learning which way is healthful to eat, and so on.
I've done 3 fasts: two of which were completely water only--one 12 day and the other a 16 day. I was eating raw food after both of those fasts. I feel that some serious healing was done on both fasts and I know that further fasts on in my future. However, learning to eat right involves much more than just fasting and expecting that to take away the cravings. It's a process and one must examine what their particular reasons are for eating less than optimal foods and get support to make those transitions.