The surgical procedure also known as bariastic surgery in which the patient's stomach is reduced significantly - like a fist might be reduced to a thumb. This procedure is not recommended for those that need to lose less than 100 lbs.
Typically, the stomach is reduced from the size of a melon to the size of an egg
The only way that Peter Jackson, that dude from Blues Traveller, and that fat chick from Wilson Phillips lost weight so fast must have been from thumb stomach. Didn't Rosanne have that too?