Hunger is the physiological drive to consume food. Several hunger hormones of the digestive system work to trigger hunger. Other hormones have the function of regulating appetite by suppressing excessive food intake.
When the stomach is empty, it releases a hormone that causes the sensation of hunger. Hormones in the digestive tract tell the brain when the stomach is full. A type of hunger hormone in the small intestines, specifically, sends a signal to the brain to end hunger pangs by causing a release of digestive enzymes.
It is important to distinguish between hunger and appetite. Whereas appetite is described as a desire for food, hunger is the biological need for food.