main focus of the diet is free foods and superfree foods.
You can have as much free food as you want, as long as with every meal, you have at least a third of your plate made up of superfree food.
Free foods: All lean meats (all visible fat/skin removed prior to cooking), fish, rice, pasta, noodles, eggs, potatoes, peas, sweetcorn, baked beans, tinned spaghetti
.
Superfree foods: All fruit and veg minus peas, potatoes, sweetcorn and one or two other starchy vegetables.
Of course there is more to it than that, but that's the core essence.