Well, the only one i can vouch for is probably height increase, since i've experienced hypnosis for something similar before. Basically, hypnosis puts you into an EXTREMELY relaxed mood. You will be more receptive subconsciously to suggestions made then. You remain aware of your surroundings all the time, contrary to popular belief.

Caveats: Advertisements are just that. Each person may have different degrees of susceptibility to hypnosis, so some people will benefit less than others.