The authors describe a case of intermittent fasting and self-induced vomiting in a student aviator whose symptoms do not meet the full criteria for either anorexia or bulimia. The range of symptomatology and differential diagnosis of eating disorders is discussed. New DSM-IV diagnostic criteria for eating disorders, including Eating Disorder Not Otherwise Specified (NOS), and associated therapeutic alternatives are reviewed. The case demonstrates the importance of comprehensive physical and psychiatric evaluation of those patients with complex or atypical presentations. Issues pertaining to the aeromedical disposition of such patients are discussed, with emphasis on the role of the flight surgeon in the early recognition of eating disorders.