Nutritionists are professionals engaged in nutrition guidance, knowledge dissemination of nutrition and food safety, and promotion of public health. The main work includes: evaluating, managing and guiding the nutritional status of human body; Evaluate, manage and guide dietary nutrition; Evaluate the nutrition of food and formula; Consultation and education of nutrition knowledge. Nutritionists can not only play an important role in publicity and education in the community, but also provide personalized education, consultation and guidance services for the catering industry, enterprise employees, white-collar workers, senior managers, athletes and families, and their employment can be found in any food-related field. At present, some hospitals or health management companies can make a complete nutritional assessment of people who come to the nutrition clinic, such as checking whether their height and weight are reasonable. Body composition analysis means that nutritionists use special instruments to detect and analyze whether the three indexes (water, fat and lean body weight, that is, musculoskeletal parts) that make up the human body are reasonable, so as to understand the characteristics of customers' daily diet. For people who are obviously "suspicious" or may suffer from certain diseases due to bad eating habits, nutritionists will advise them to do trace element determination and testing. The nutritional evaluation composed of these four steps is a whole, which is a very natural and coherent process for experienced nutritionists. The specific operation flow and inquiry can be deep or shallow, fine or rough, and maybe a few questions can complete this step. After completing the nutritional assessment, the nutritionist will prescribe a "prescription". "Prescription" is mostly a basic plan for the future diet, including specific suggestions on the basic composition of food, the number of meals, the time of meals, and the way of meals. The recipe will be redesigned according to the different reactions of each patient.