A porous weave of bioabsorbable filaments having an open mesh configuration is formed into an oblate shape having dimensions greater than the esophageal opening and gastric outlet of a stomach. The resulting prosthesis is deployed in the stomach and is of a size to be retained in the proximate portion thereof for exerting pressure on the upper fundus. The prosthesis limits the amount of food that may be held within the stomach, and exerts pressure on the fundus to create a sensation of being full, resulting in weight loss.