I've used this method. Even if he talks about things like mind over matter and losing weight trough visualization the premises are pretty scientific.
In fact, Jon Gabriel is biochemical researcher.
However, this is for sure worth a try: even if it isn't a totally exerciseless method (he suggest you to do some light fitness) the results are amazing.
Using this method I was able to lose more than 30 pounds.
But, as a lot of people who are using this method can tell you, the best thing about it is not the weight loss, but the change of mentality: after the course I never had a craving again.
Btw, I've written a review about this: my review