Food intake consists in meal size multiplied by meal number which constitutes a feeding pattern. Specific analysis of these parameters is of particular of interest since they are controlled by distinct brain areas and neurochemical messengers, and reflects different physiological significance (meal size relates to satiation, whereas meal number relates to satiety). Moreover, whereas drinking has generally not been considered in meal definition, a close temporal relationship exists between eating and drinking. In this way, a precise monitoring of food and drink intake (amount and meal pattern analysis) along the circadian circle is necessary to evaluate fine alterations of these functions, in response to treatments, brain lesions or genetic manipulations. Food and drink intake is a parameter that can be evaluated together with indirect calorimetry in metabolism studies.