In my opinion - again coming from someone that's cycled this several times - does taking GW automatically make your body burn fat? Well....kind of BUT it doesn't do the work for you. The way GW has worked for ME is I'm able to do more intense , longer cardio sessions with virtually no recovery time. Because you're going balls-to-the-wall your body is able to fire on all cylinders which mean you burn more calories. By no means does this mean you can eat what ever you want and not gain a pound. It makes cardio so, so much easier thus allowing your body to work harder and burning more calories.
Long story short - yes I cut a good amount of weight on GW.