Physiological regulation of the human energy balance appears insufficient in an environment which abounds in palatable food. Human feeding behavior is predominantly controlled by cognitive factors. Behavior and cognitions in the obese are relatively more externally and less internally physiologically controlled, which increases the chance of balance distortion. Little physical activity and small range of adaption of basal metabolism contribute to difficulties in maintaining normal body weight. Psychiatrie deviation is not important in development of obesity, but secundary problems may arise. Weight reduction methods commonly aim at increasing cognitive control. However, a lasting improvement by cognitive and behavior change techniques has not been proved.