A device for performing one or more functions in a gastrointestinal tract of a patient includes an anchoring member and at least one actuator, sensor, or combination of both coupled with the anchoring device. The anchoring device is adapted to maintain at least part of the device within a pyloric portion of the patient's stomach and to intermittently engage, without directly attaching to, stomach tissue. Actuators perform any suitable function, such as transmitting energy to tissue, acting as a sleeve to reduce nutrient absorption, occupying space in the stomach, eluting a drug and/or the like. Sensors may be adapted to sense any suitable patient characteristic within the patient's gastrointestinal tract, such as pH, temperature, bile content, nutrient content, fats, sugars, alcohol, opiates, drugs, analytes, electrolytes and/or hemoglobin.