A gastric restrictor assembly for positioning about a portion of the digestive tract, e.g., stomach, esophagus, etc., of a patient to treat obesity is disclosed. The gastric restrictor assembly includes an inner expandable member and an outer collar. The inner expandable member is dimensioned to be transesophagealy positioned within the digestive tract, e.g., stomach. The outer collar is dimensioned to be positioned about the digestive tract, e.g., the stomach, and the inner expandable member to clamp the stomach therebetween. The inner expandable member defines an opening therethrough. The diameter of the opening is selectively adjustable via a fill tube to selectively control the diameter of the central opening.