1. ¹Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
2. ²Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
3. ³Department of Clinical and Translational Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA

Correspondence: Kimberly A. Brownley (kbrownle@med.unc.edu)

Received 14 November 2008; Accepted 21 September 2009; Published online 29 October 2009.

Abstract

Black women suffer a disproportionately higher rate of obesity than their white counterparts. Reasons for this racial disparity may reflect underlying differences in the appetite suppressing peptide-YY (PYY). The PYY response to food is differentially influenced by macronutrient content but the effect of glycemic load on PYY response is unknown. This study examined whether glycemic load influences fasting and postprandial PYY levels and whether fasting and postprandial PYY levels are lower in obese black women compared to normal weight black women and to white women. Data were collected from 40 women (20 black, 20 white; 10 each normal weight vs. obese) at the University of North Carolina Clinical and Translational Research Center (CTRC). Participants completed in counterbalanced order two 4½-day weight-maintenance, mixed macronutrient high vs. low glycemic load diets followed by a test meal of identical composition. Total PYY levels were assessed before and after each test meal. Results show no differences in fasting PYY levels but significantly less postprandial PYY area under the curve (PYY_AUC) in the group of obese black women compared to each other group (race obesity interaction, P < 0.04). PYY_AUC was positively related to insulin sensitivity (P < 0.004) but was not affected by glycemic load (main and interactive effects, P > 0.27). These findings indicate that postprandial PYY secretion is not affected by glycemic load but is blunted in obese black women compared with normal weight black women and with white women; additionally, they begin to address whether blunted PYY secretion contributes uniquely to the pathogenesis of obesity in black women.