Ghrelin, Peptide YY, Glucose-Dependent Insulinotropic Polypeptide, and Hunger Responses to a Mixed Meal in Anorexic, Obese, and Control Female Adolescents

Abstract

To determine whether peptide YY (PYY), ghrelin, glucose-dependent insulinotropic polypeptide (GIP), and satiety responses to food intake are impaired in anorexia or obesity, we studied 30 female adolescents with anorexia nervosa [body mass index (BMI) 16.3 kg/m2], obesity (BMI 34.3 kg/m2), or normal weight (BMI 20.2 kg/m2). PYY, ghrelin, GIP, insulin, and glucose concentrations and four markers of satiety were measured for 240 min after a mixed meal. The area under the curve for glucose was similar in obese (OB) and normal-weight control (C) subjects but was 15% lower in anorexic (AN) subjects. The area under the curve for insulin was 47% lower in AN and 87% higher in OB subjects, compared with C subjects. After the meal, PYY increased significantly in C (+41%, P < 0.05) but not in AN or OB adolescents. Ghrelin concentrations were highest in AN subjects and lowest in the OB group, compared with C subjects and fell significantly by 25% in all three groups. GIP concentrations were lower in AN subjects throughout the test and increased in all three groups after the mixed meal. AN adolescents reported being less hungry than OB and C adolescents. There was a negative correlation between fasting ghrelin (but not PYY or GIP) and BMI and insulin (r2= 0.33) and a positive correlation between the decrease in hunger 15 min after the meal and PYY concentrations at 15 min (r2= 0.20). In conclusion, the blunted PYY response to a meal in OB adolescents suggests that PYY plays a role in the pathophysiology of obesity. Ghrelin is unlikely to play a causal role in anorexia nervosa or obesity. The lower GIP observed in AN subjects despite a similar caloric intake may appropriately prevent an excessive insulin response in these patients.