i have just found this on s/w online
: Is a third of a plate of Superfree Food mandatory on the Extra Easy plan?
A: No, we'd never insist you eat in a way that might not suit you. However, we encourage you to include a third of a plate of Superfree Food to keep Extra Easy extra low energy density (low calorie), extra satisfying and extra healthy to optimise weight loss.
Q: What are Superfree Foods?
A: Superfree Foods are super-satisfying for the appetite and very, very low in calories (or energy density). Fill one third of your plate with Superfree Foods and make them your first choice between meals. You’ll naturally limit your energy intake without counting a single calorie, and you’ll be enjoying a really healthy diet, making your weight loss success extra easy!
These include:
Fresh and frozen fruit
Vegetables - excluding potatoes, parsnips, sweetcorn, peas (apart from sugar snap and mange tout) and beans (apart from green varieties)
For the complete list, see your Food Optimising book.