The Academy of Nutrition and Dietetics defines a registered dietitian as:
A food and nutrition expert who has met the minimum academic and professional requirements to qualify for the credential “RD.” In addition to RD credentialing, many states have regulatory laws for dietitians and nutrition practitioners.
A registered dietitian is therefore, not an exercise therapist offering nutrition advice or an everyday individual offering nutritional guidance based on a book they may have read.
Rather, a registered dietitian is an accredited individual who specializes in providing medical nutrition therapy to patients with a variety of medical conditions.
While this can include treating patients with weight management issues such as obesity or anorexia, it also includes treating other serious conditions such as diabetes, renal disease and food related issues arising from pregnancy .