Effects of meals high in carbohydrate, protein, and fat on ghrelin and peptide YY secretion in prepubertal children.
BACKGROUND
Ghrelin and peptide YY (PYY) are two hormones produced by the gastrointestinal tract that have effects on appetite. However, little is known about their secretion in response to meals high in individual macronutrients in prepubertal children.


OBJECTIVE
We sought to understand how meals high in carbohydrate, protein, and fat affect serum concentrations of total ghrelin and total PYY, hypothesizing that these macronutrients would exert differential effects on their secretion.


METHODS
This was a cross-sectional study at one tertiary care center.


METHODS
Subjects were 7- to 11-yr-old healthy normal-weight (NW) and obese (OB) volunteers recruited from local advertisements.


METHODS
After an overnight fast, the subjects were given a breakfast high in carbohydrate, protein, or fat at 0800 h. Blood samples for total ghrelin and total PYY were taken at baseline, 30 min, and hourly from 0900 to 1200 h.


METHODS
We assessed postprandial ghrelin suppression and PYY elevation, as well as changes in reported hunger and satiety, after the three test meals.


RESULTS
After the high-protein meal, ghrelin declined gradually in both groups over the study period without subsequent increase, whereas ghrelin suppressed more rapidly to a nadir at 60 min after the high-carbohydrate meal in both NW and OB children, followed by rebound in ghrelin levels. Similarly, after the high-protein meal, PYY concentrations increased steadily over the course of the morning in both groups without decline, whereas PYY levels peaked 30 min after the high-carbohydrate meal in both NW and OB subjects with significant decline thereafter. Ghrelin and PYY responses to the high-fat meal were somewhat intermediate between that observed with high carbohydrate and high protein. The OB children reported higher hunger and lower satiety after the high-carbohydrate meal compared to the NW subjects, whereas appetite ratings were similar between the groups after the high-protein and high-fat meals. Additionally, within the OB group, area under the curve (AUC) analysis revealed significantly greater PYY response, as well as lower AUC hunger and higher AUC satiety, to the high-protein meal than the high-carbohydrate and high-fat meals.


CONCLUSIONS
The patterns of secretion of ghrelin and PYY in our study of prepubertal children suggest that they may play a role in the effectiveness of high-protein/low-carbohydrate diets in promoting weight loss.
Lomenick
Jefferson P
JP
Department of Pediatrics, Division of Endocrinology and Molecular Medicine, University of Kentucky College of Medicine, Lexington, Kentucky 40508, USA. jefferson.lomenick@vanderbilt.edu
Melguizo
Maria S
MS
Mitchell
Sabrina L
SL
Summar
Marshall L
ML
Anderson
James W
JW
D019540:Area Under Curve; D002648:Child; D003430:Cross-Sectional Studies; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004041:Dietary Fats / Q000494:pharmacology*; D004044:Dietary Proteins / Q000494:pharmacology*; D054439:Ghrelin / Q000097:blood / Q000378:metabolism*; D006801:Humans; D019894:Peptide YY / Q000097:blood / Q000378:metabolism*; D011627:Puberty; D012016:Reference Values; D012527:Satiation / Q000502:physiology
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D054439:Ghrelin; D019894:Peptide YY