A fluid reservoir for use in a remotely adjustable gastric banding system comprises a housing and a flexible reservoir pouch positioned within the housing. The flexible reservoir pouch is coupled to an inflatable portion of a gastric band via flexible tubing. A pump coupled to the flexible reservoir pouch facilitates filling and draining the inflatable portion of the gastric band. The pump may be located within or outside of the housing. A receiving coil may be coupled to the housing, and the receiving coil forms a loop around the housing. The receiving coil receives radio frequency signals to drive the pump. A circuit board may be disposed in the housing for driving the pump to move the fluid between the flexible reservoir pouch and the inflatable portion of the gastric band. A portion of the circuit board may be a flexible circuit board to allow the housing to flex.