Eating disorders affect a significant number of individuals across the life span and are found among all demographic groups (including all genders, socioeconomic statuses, and ethnicities). They can cause malnutrition, which can have significant effects on every organ system in the body. Cardiovascular complications are particularly dangerous and cause eating disorders to have the highest mortality rate of all mental illnesses. This article outlines the medical assessment and treatment of malnutrition due to disordered eating.