Hi Purple Mummy, I am sure that you will do well on the Gabriel Method - as his plan is based on recent research and personal experience - not just outdated myths or theories.
No foods are forbidden BUT:-
It is important to eat sufficient HIGH NUTRITION food - so that your body is not making you hungry (in the hope that it will get sufficient protein, vitamins, minerals, amino acids etc). This means that you should eat high nutrition foods FIRST - and AT EACH MEAL - then eat other foods (if you still really want to). You should also include small quantities of good quality fats (which help prevent wrinkles as you lose weight).
It is important to eat small, high-quality meals frequently throughout the day. Each of these meals should contain high-quality protein (protein also reduces hunger) - but not too much protein or fat.
These two strategies will convince your body that there is no shortage of nutrients, and once your body has restored its nutrients, your appetite and cravings will reduce and dissapear. This may take a little while (depending on your present nutrient status) but it WILL happen. Once you reach this point, it is absolutely amazing not feeling that you are a slave to your hunger and cravings.
All these points are explained in Jon's book - and the vizualization CD is very helpful as well.