A dynamically controlled gastric occlusion device monitors at least one physiological parameter that varies as a function of food intake and controls the degree of gastric constriction of an occluding device, such as a gastric band, based on the monitored physiological parameter. In another embodiment, the dynamically controlled gastric occlusion device controls the degree of gastric constriction based on time. The occluding device is dynamically opened or closed to either permit or prevent the passage of food through the gastrointestinal (GI) tract. By dynamically controlling the degree of gastric constriction, the device limits the ingestion of food to reduce caloric intake so that the patient loses weight while permitting the ingestion of water and the minimum amount of caloric energy necessary to prevent malnourishment.