This study looked at the PYY response to meals in normal people and people with anorexia. Recall that PYY is a potent satiation hormone secreted from the gut, it tells you STOP EATING, and it shifts your attention away from food and hunger. In the graph below we see that not only do people with anorexia have elevated baseline PYY, the response of PYY after a meal shoots up off the scale almost. What does this mean?
It means that people with anoerxia are told by their bodies to curb food intake, contrast this to an obese people, that typically has a much reduced PYY not only at baseline but in response to food.