(1) a diet having a caloric value equal to the basal heat production and sufficient quantities of essential nutrients to meet basic needs; (2) in experiments in nutrition, a diet complete and adequate except for a single constituent (e.g., a vitamin, mineral, or amino acid), the nutritional value of which is to be determined, is omitted for a period and the effects observed; the subject is observed for a second period during which the ingredient being studied is added to the diet.
