A method and apparatus are disclosed for treating obesity includes an artificial fistula created between gastrointestinal organs such as between the stomach and the colon. The method includes selecting an implant comprising a passageway having an internal lumen with an inlet end and an outlet end. The passageway is positioned passing through a first wall of first gastrointestinal organ (for example, passing through the wall of the stomach) and a second wall of a second gastrointestinal organ (for example, passing through the wall of the large intestine) with the inlet end disposed within an interior of the first gastrointestinal organ and with the outlet disposed within an interior of the second gastrointestinal organ.