The present invention provides systems and methods for treating and controlling obesity and/or type II diabetes. In one aspect of the invention, a device comprises a hollow sleeve sized and shaped for positioning within a duodenum of the patient, an anchor coupled to the proximal end of the sleeve and being sized and shaped to inhibit distal migration of the sleeve and a plurality of elastomeric objects coupled to the distal end of the sleeve and being sized and shaped to inhibit proximal migration of the sleeve through a pylorus of the patient. The bypass device can be placed and removed endoscopically through the patient's esophagus in a minimally invasive outpatient procedure and it is “self-anchoring” and does not require invasive tissue fixation within the patient's GI tract, thereby reducing collateral tissue damage and minimizing its impact on the digestive process.