All participants in this observational study will be administered a taste test to determine if they can consciously differentiate between a sugar solution and an artificially sweetened solution. Participants may also perform several brief computerized tests, ranging from 3 to 10 minutes each, to evaluate thinking, memory, and information processing skills. Participants who cannot tell the difference between the solutions will undergo a functional magnetic resonance imaging (fMRI) scan, which will take pictures of the brain and blood flowing through the brain. Prior to the scan, blood and urine collection may occur, and participants may complete two additional computerized tests. The scan will require 60 to 90 minutes to complete. During the scan, participants will hold two thin tubes in their mouth. At various intervals, these tubes will deliver 1 ml of liquid containing either sugar water or an artificial sweetener into each participant's mouth. A screen projection of abstract pictures will also be shown to each participant throughout the scan, either before the liquid is delivered or alone. This study will require a 6- to 9-hour time commitment. The results from this study may provide valuable information regarding anorexia nervosa and bulimia nervosa and may eventually lead to the development of new and better treatment options for these complex and serious disorders.