Well, I was a little dubious about the diet, but it definitely works and is actually really well thought out. My first week I lost 8/5 pounds which is pretty amazing.
The principle of the diet is to have lost of "free" food, which are relatively calorie poor. You can have as much as you like and it fills you up, so you end up losing weight. It's very surprising when it includes lean meat, eggs, potatoes and pasta - yes, you heard that right! It works, so I'm happy to accept that and will carry on with it.
As to cooking I've been cooking all sorts of things but just cutting down on fats and oils in particular, but also some carbs - anything with sugar and most breads. It's actually pretty easy to reduce the bad ingredients and up the good ones, so we are eating really well.
That's it for now, but I'm impressed and will be sticking to it all :)