You get a whole new book which guides you through management and then you have the counselling too.
Basically at the end of the 12 weeks, it is your choice as to what way you want to go, but generally they guide you towards low to medium GI and low fat. It is really just about eating healthily and sensibly, but not cutting anything out completely unless you have a problem with it.
You do have a week where you reintroduce what they call staples, potatoes, pasta, rice, etc, then a bread week, cheese week, snacks. They call them trigger weeks, you need to see how you can handle each group.