The part of the body that motivates eating is the hypothalamus. The small gland is located in the midline at the base of the brain, just below the hypothalamus, and interacts closely with the pituitary gland and acts in coordination with the reticular formation. The two components of the hypothalamus dealing with hunger are the lateral hypothalamus and the ventromedial nucleus. The lateral part is what allows a person to feel hungry and sends out signals to the rest of the body that one is ready to eat. If this part is damadged, one would not feel hunger and would experience aphasia, which is starving. The ventromedial nucleus gives satiety, or the feeling that one is full. This component is also necessary, because an injury here would produce hyperphasia, when the body does not know when to stop eating, and would surely become obese.
Along with his theory of emotions, Schachter studied obesity and the reasons for the uncontrollable urges to binge by those who are overweight. His research reveals that much of the overeating is due to the reinforcements that the obese find in food. He mentions that while those with an appropriate weight are stimulated to eat when aroused by internal cues, obese look for other factors to reinforce their need to eat. For example: the smell of food, the way a platter is served, the colors and decorations on a plate, or even the contact comfort that the food produces in the hands or in the tongue. This euphoric way of eating might be satisfying during dinner time, but in the long run, it is extremely dangerous. By eating only what appeals to vision, smell, or texture, one does not satisfy the bodily needs for varied nutrients, vitamins, and minerals, and therefore be mal-nutrinioed and be exposed to obesity and other illness as well.