Restricting foods that you can and can't eat, labelling foods as "bad" or having designated "cheat days" can all lead to binge eating, and an unhealthy relationship with food.
If you restrict yourself too severely (either by restricting certain foods or restricting calories, or both), you WILL break it at some stage.
Then your mindset will change to "oh I've already ruined my diet by eating a piece of chocolate, so I may as well eat the whole block."
This is how binge eating starts. The way to prevent this is by not restricting foods and not labelling them as good or bad.