A method of, and device for, slowing the passage of food through a digestive tract of a patient and thereby treating obesity. The device is an obesity tube comprising (A) an upper ring of a size corresponding to a point under a patient's esophagus and above the patient's diaphragm muscle, and (B) a lower tube having a length and a distal opening. The method comprises stapling the upper ring under the patient's esophagus, above the patient's diaphragm muscle, and placing the lower tube distal to the upper ring. The length of the lower tube depends on whether the tube is to terminate distally in the stomach or terminate past the pylorus, in which case a section can be provided which is thick enough to resist collapsing under pylorus pressure. The lower tube can be entirely or partially non-permeable or semi-permeable. Semi-permeable tubes or sections thereof have walls which permit the passage of gastric hydrochloric acid but not food.