Objective: Obesity prevalence is higher in African American (AA) vs. American White (AW) youth. Ghrelin is a "hunger" peptide high preprandially and decreases postprandially, and peptide YY (PYY) is a "satiety" hormone increasing after meals. Impaired regulation of ghrelin/PYY may be conducive to obesity. We hypothesized that racial differences in childhood obesity could partly be explained by differences in ghrelin/PYY dynamics.

Research Design and Methods: We investigated: 1) ghrelin suppression/ PYY elevation in response to an oral glucose tolerance test (OGTT) in AA vs. AW, and 2) the relationship of ghrelin and PYY dynamics to insulin sensitivity (IS).

Thirty-three AA and 54 AW prepubertal children underwent an OGTT measuring ghrelin, PYY, glucose, and insulin. Fasting glucose to insulin ratio (G_F/I_F) was used to assess the relationship of IS to fasting and post OGTT ghrelin and PYY levels.

Results: OGTT-induced suppression in ghrelin ( ghrelin) was lower in AA youth. ghrelin correlated with G_F/I_F (r=0.47, P < 0.001) and with insulin at 30 min (r0.47, P < 0.001). In multiple regression analysis, race (P = 0.013) and G_F/I_F (P = 0.004) contributed independently to the variance in ghrelin (R²=0.28, P < 0.001). Fasting and post OGTT PYY levels were lower in AAs and were not related to insulin sensitivity.

Conclusion: The lower suppression of ghrelin in AA, but not the lower PYY levels, correlates with insulinemia and insulin resistance. Less ghrelin suppression and PYY elevation after a meal in black youth could be a potential mechanism of race related differences in hunger/satiety predisposing to risk of obesity.