We experience hunger when the level of

a. ghrelin in our blood is low.

b. leptin in our blood is low.

c. glucose in our blood is low.

d. pyy in our blood is high.

Glucose in our blood is low

Hunger and satiety is a sensation. Hunger can represent the need for food physiologically. This is also associated with the contractions of stomach or intestine and can be described as the emptiness. The role of glucose in hunger is well studied. The drive to eat can be produce by the damage to some parts of the brain, commony in the hypothalamus and pituitary area. When these happens animals or humans can be a voracious eater.