The search of animals for food is driven by a chemosensory code that senses the nutritional value of the available sources. Foods enter the gastrointestinal tract (GIT) through the oral cavity where its components are scrutinized and discriminated according to several chemical and physical parameters before swallowing. In hunger the chemosensory systems located in the oronasal cavity (mainly smell and taste) sense dietary nutrients and trigger or discourage further consumption. Via the GIT-hypothalamus axis peripheral sensing determines the cephalic phase of food consumption and has a direct and immediate (short term) impact on meal initiation and presumably meal size.