In some embodiments, an extragastric balloon is described in which the balloon is contoured to fit a portion of the stomach but not circumscribe the stomach. In some embodiments, the extragastric balloon comprises multiple material components. In some embodiments, the extragastric balloon comprises multiple inflateable compartments. In some embodiments, the extragastric balloon is filled with one or more of a gas, liquid, solid, or foams to create portions of the balloon with differing densities or buoyancies. In some embodiments, multiple anchors contact the stomach, each of which are inflateable with a fluid such as a liquid, gas, or gel. In some embodiments, a pressure sensor is described which is programmable from a place external to the patient and can be programmed to increase its sampling frequency when an ingestion event is detected.