A gastrointestinal device for implanting within a pylorus, a duodenal bulb, and a duodenum of a patient's gastrointestinal tract includes an expandable structure including 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. 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.