An obesity treatment device comprises a filament filler material movable between a substantially straight insertion/removal configuration and an operative configuration in which the filament extends along a predetermined curve to occupy a selected volume within the stomach and a retrieval device connected to a proximal end of the filler material facilitating grasping and withdrawal of the filler material. A method of treating obesity, comprises inserting to a desired position within the GI tract a filament filler in a substantially straight configuration and moving the filler into an operative configuration in which the filler curves along a predetermined path to define a desired volume in combination with, after a predetermined treatment period has elapsed, collapsing the filler into the substantially straight configuration for trans-oral removal.