Apparatus is provided for use in a stomach of a subject, including a gastric balloon and a hollow, flexible tube coupled at a distal end thereof to the gastric balloon. A proximal portion of the tube, when in a relaxed position, is shaped so as to prevent the balloon from passing into a duodenum of the subject. The apparatus also includes an inflation conduit disposed in part within the distal end of the tube, the inflation conduit exiting the tube at a site proximal to the gastric balloon. Other embodiments are also provided.