A gastrointestinal device for implanting within a pylorus, a duodenal bulb, and a duodenum of a patient's gastrointestinal tract includes an expandable structure includes a proximal portion having a plurality of spring arms and a distal portion having a plurality of spring arms, the proximal and distal portions coupled by a rigid central cylinder having a diameter capable of fitting within the pylorus and having a length greater than a width of the pylorus. A membrane is coupled to and covering at least a portion of one of the proximal portion and the distal portion of the expandable structure. An intestinal bypass sleeve is coupled to at least one of the proximal and distal portions of the expandable structure and having a length sufficient to extend at least partially into the duodenum. In the expanded configuration, the proximal portion has a diameter larger than a maximum opening diameter of the pylorus and further wherein, in the expanded configuration, the distal portion has a diameter larger than a maximum opening diameter of the pylorus.
