A food intake restriction device for forming a stoma opening in the stomach or esophagus of a patient comprises an elongated restriction member (2), forming means for forming the elongated restriction member into at least a substantially closed loop around the stomach or esophagus, said loop defining a restriction opening, and an adjustment means for adjusting the restriction member in said loop to change the size of the restriction opening. The device further comprises implantable hydraulic operation means (6,8) provided for operating the adjustment means in a non-invasive manner, and an implantable reservoir (4) containing a predetermined amount of hydraulic fluid. The hydraulic operation means are adapted to operate the adjustment means by using the hydraulic fluid of the reservoir.
