A satiation device is described which includes a sheath or liner extending from the proximal or middle stomach to the distal antrum. Food ingested by the patient passes through the sheath or liner, thereby minimizing contact between the ingested food and the stomach. It is believed that over time, reduced contact between food and the stomach will result in decreased Ghrelin production by the patient and a consequent decrease in appetite. In some embodiments, the satiation device may also include a proximal pouch and/or a distal bypass tube.