Obesity, defined by body fat excess, results from a food intake which exceeds energy needs. The control of this intake is compromised in people suffering from obesity. There is a disturbance of the food reward brain network, in the form of an abnormal reactivity to visual and gustatory food signals and a disrupted influence of the state of hunger on its activity as well as an alteration in the dopaminergic neurotransmission. Eating would thus be leaded more by its hedonic supply rather than physiological needs and this imbalance would appear among the mechanisms underlying overeating behavior. A better understanding of obesity neurobiology would ultimately contribute to the improvement of therapies and preventive measures.