1. A gastric banding device for forming a stoma opening in a stomach so as to restrict food intake to the lower digestive portion of the stomach, said device comprising: an elongate band member including a band portion for, in use, encircling a stomach to form a stoma opening in the stomach, said band member including a free end and an intermediate portion having a thickness greater than the thickness of the remainder of said band member; an expandable section secured to said band portion of said band member for varying the size of the stoma opening; a securing member located near said free end of said band member and protruding outwardly therefrom; a recess, formed in said intermediate portion of said band member, for receiving said securing member therein; and means, including a movable control member separate from said securing member, for positively retaining said securing member in said recess so that said band portion forms a circle of a predetermined fixed diameter around said stoma opening.