DC law requires a license to practice nutrition and dietetics, which they define as "the application of scientific principles and food management techniques to assess the dietary or nutritional needs of individuals and groups, make recommendations for short-term and long-term dietary or nutritional practices which foster good health, provide diet or nutrition counseling, and develop and manage nutritionally sound dietary plans and nutrition care systems consistent with the available resources of the patient or client.”
Unless a person holds a license to practice dietetics or nutrition, a person shall not use or imply the use of the words or terms "dietitian/nutritionist," "licensed dietitian," "licensed nutritionist," "dietitian," "nutritionist," "L.D.N.", "L.D.", "L.N.", or any similar title or description of services with the intent to represent that the person practices dietetics or nutrition.
Very narrow exemptions exist for dietetic technicians and dietetic assistants working under the supervision of a licensed dietitian or nutritionist, other health professionals who are licensed within their profession, or other persons who in the course of their responsibilities offer dietary or nutrition, information or deal with nutritional policies or practices on an occasional basis incidental to their primary duties, provided that they do not represent by title or description of services that they are dietitians or nutritionists.
Source: § 3-1201.02 of the District of Columbia Official Code, Subsections 6(A) and 6(B).