Umm actually I think it's not about what you eat, is about how much you eat.
Take an example,
What is consider "healthy": wheat bread, skim milk, etc...
What is consider "unhealthy": potato chips, icecream, etc...
If you eat all the things considered "healthy", but in a great amount, e.g. eating 10 pieces of wheat bread a day, it would even be fatter than eating a small pack of photo chips or a cup of icecream.
So, in my opinion, I would not "banned" food, because banning food would cause you wanting to eat that food much more. If you really want to eat unhealthy food, give yourself a little "bonus". You can eat it but in a small small small amount. And eat healthy in other times.
It's not about banning, it's about balancing.