UNIT:-(II) CLASSIFICATION OF FOOD, Introduction:- Essential Nutrients required for the body include Protein, Carbohydrate, Fat, Contains Vitamins, Minerals and Water. Classification of Food The classification of food according to origin, functions, chemical composition, sources & nutritive value is as follows. A) Classification by origin, 1) Food of animal origin 2) Food of vegetable origin B) Classification by predominant functions, (1) Body building food 2) Energy giving food (3) Protective food