A specialist in adapting and applying food and nutrient knowledge to the solution of food and nutritional problems, the control of disease, and the promotion of health. Nutritionists perform research, instruct groups and individuals about nutritional requirements, and assist people in developing meal patterns that meet their nutritional needs; (2) A nutritionist is someone who has completed undergraduate and/or graduate training in the discipline of nutrition without necessarily meeting the academic and experience requirements to qualify for the Registered Dietitian designation.