How can damage to the ventromedial hypothalamus lead to overeating?

The ventromedial hypothalamus functions as a critical clearinghouse for satiety signals within the brain’s complex network for regulating feeding behaviour.

When this area is damaged or destroyed, the brain loses its ability to effectively process the signals that normally indicate a subject has consumed enough energy. Consequently, the subject fails to stop eating at a normal level of caloric intake. This leads to hyperphagia—a state of gross overeating—as the subject continues to consume food until reaching an abnormally high level of body energy content, often resulting in obesity.12

In contrast, the lateral hypothalamus acts as a hunger center that facilitates feeding; its destruction typically leads to a loss of the urge to eat, known as aphagia. Together, these regions maintain a balance between hunger and satiety to keep body weight relatively constant.12