well......... (you're going to wish you hadn't asked now! )
He teaches how to distinguish between actual hunger and emotional hunger wether that be from stress, boredom, upset etc. so that you eat whatever you want so long as you are hungry.
You have to eat slowly so that you can taste the food and also relise when you are full so you can stop rather than clearing your plate just beacuse your mother taught you to.
There are lots of habits that habitual dieter's have - like weighing themselves more than they should or eating quickly without thinking until the plate is empty rather than just eating enough to fill them up, or eating diet food because they think they should but then still craving nice food, or starving themselves if they have preiously binged.
It also teaches you how to speed up your matabolism by listening to your body's hunger signals.
There are also techniques to overcome cravings when your not hungry and also lots of techniques about being able to like your body.
The list goes on and on - infact he should be paying me for all the promotion I've done for him this week!