The nutrition is the set of processes by which a living being transforms food for its operation. Nutrition is also a multidisciplinary science, with two main themes. On the one hand, the physiology of nutrition deals with how the body processes food processing, that is, metabolic processes. This involves studying the role of macronutrients and micro nutrients at the level of the cellular biochemical mechanisms, and the consequences on the tissues of an imbalance between the absorbed energy and the energy expended by the organism. On the other hand, the psychology of nutrition analyzes the eating behavior of the individual or group. It focuses on issues such as "why are we eating? Or "how do we choose our food? ". In humans, these issues are related to environmental factors such as the built environment, the media and health policies, as well as its particularities such as income or culture.