FIGURE 8.1 Blood Glucose and the Motivation to Eat In this graph, the red dots depict the effects of insulin triggering a small decline in blood glucose over the course of about 30 minutes. As blood glucose decreases, the person’s subjective desire to eat increases sharply, depicted by the green line. Notice that although this person did not eat, his blood glucose level returned to normal within the hour and his desire to eat diminished. In daily life, a small decline in blood glucose level is just one of the many different factors that reliably predict our motivation to eat.

Source: Data from Campfield & others (1996).