The term "hunger hormone" refers to a group of hormones that regulate appetite, food intake and energy balance in the body. The primary hunger hormone is ghrelin, which is produced by the stomach and stimulates feelings of hunger. Other hormones such as leptin (produced by fat cells) and insulin (produced by pancreas) also play a role in regulating appetite and energy balance. These hormones work together to maintain a healthy body weight, but imbalances can lead to conditions like obesity or anorexia nervosa.