A novel medical device for treating obesity is disclosed. The device is inserted through the oral cavity and into the digestive tract of a human. The device is a passive catheter-style structure that preferentially directs a significant volume of the high calorie fluidic components of the chyme through the digestive tract, preventing exposure to the absorptive tissues of the digestive tract and, in some forms, stimulates negative feedback to the patient when simple sugars and carbohydrates are consumed. The device may be installed or removed though the use of standard endoscopy, or may be offered in the form of an ingestible device. The device may be inflatable or preformed for use within the digestive tract. Also disclosed is a novel method of using the medical device to control obesity.