Registered Dietitian Nutritionists (RDN) must complete a four-year program in Nutrition from an accredited university, 1200 hours of supervised practice, or a master’s degree. Upon completion of the program, they must pass a national exam. An RDN is generally located in a clinical setting such as a hospital. They often evaluate and help patients with conditions such as diseases, lipid disorders, food allergies, and other medical conditions that can be improved by eating.