PYY and obesity due to melanocortin 4 receptor deficiency: The detailed objectives were to: 1) test if PYY is associated with obesity status by comparing fasting serum PYY between normal-weight (NW), overweight (OW) and obese (OB) men and women; 2) examine the association of PYY with body composition among normal-weight (NW), overweight (OW) and obese (OB) men and women; and 3) determine the influence of age, sex, smoking, medication use and menopausal status on circulating PYY.