Systematic review and meta-analysis of the effect of meal intake on postprandial appetite-related gastrointestinal hormones in obese children.

UNLABELLED: Understanding the physiological response to meal intake, of gut-derived appetite and satiety hormone signals, in obese compared with healthy-weight children may assist with informing strategies to help curtail the obesity epidemic. A systematic review and meta-analysis of studies investigating the acute postprandial response of gastrointestinal appetite hormones to meal intake in obese children was undertaken. Systematic searches of databases EMBASE, CINAHL Plus, OVID Medline and the Cochrane Library were performed. INCLUSION CRITERIA: a randomised controlled trial or experimental cross-sectional study following an acute test meal protocol with pre- and postprandial analysis of plasma or serum gastrointestinal hormone concentrations. Database searching retrieved 1001 papers for review. Nine studies met the inclusion criteria, collectively reporting on six appetite hormones yielding a total of 32 test meal-hormone comparisons. Meta-analyses compared the pooled estimate of the mean difference of the postprandial change in total ghrelin and total peptide YY (PYY). Obese compared with healthy-weight children had an attenuated change in ghrelin at 60 min (N=5 studies; n=129 participants) and 120 min postprandial (N=4 studies; n=100 participants) (P<0.05 for both time points). Obese compared with healthy-weight children also had an attenuated PYY response at 60 min (N=5 studies; n=128 participants) and 120 min postprandial (N=4 studies; n=100 participants). Insufficient studies reported on the postprandial time course of other appetite-related hormones, precluding a meta-analysis. Limited evidence notwithstanding, these findings indicate that PYY and ghrelin responses to a meal may be altered in obese children. This review has also identified a major gap in knowledge of hormonal appetite responses in childhood obesity. More comprehensive investigations of the homoeostatic regulation of gut-derived appetite and satiety hormone signals with behavioural and clinical outcomes are warranted to understand if there are consequences of these differences.

Fasting gut hormone levels change with modest weight loss in obese adolescents.

BACKGROUND: Gut hormones change with weight loss in adults but are not well studied in obese youth. OBJECTIVE: The primary aim was to evaluate how gut hormones and subjective appetite measure change with dietary weight loss in obese adolescents. METHODS: Participants were a subset of those taking part in the 'Eat Smart Study'. They were aged 10-17 years with body mass index (BMI) > 90th centile and were randomized to one of three groups: wait-listed control, structured reduced carbohydrate or structured low-fat dietary intervention for 12 weeks. Outcomes were fasting glucose, insulin, leptin, adiponectin, total amylin, acylated ghrelin, active glucagon-like peptide-1, glucose-dependent insulinotropic polypeptide (GIP), pancreatic polypeptide (PP) and total peptide tyrosine-tyrosine. Pre- and postprandial subjective sensations of appetite were assessed using visual analogue scales. RESULTS: Of 87 'Eat Smart' participants, 74 participated in this sub-study. The mean (standard deviation) BMI z-score was 2.1 (0.4) in the intervention groups at week 12 compared with 2.2 (0.4) in the control group. Fasting insulin (P = 0.05) and leptin (P = 0.03) levels decreased, while adiponectin levels increased (P = 0.05) in the intervention groups compared with control. The intervention groups were not significantly different from each other. A decrease in BMI z-score at week 12 was associated with decreased fasting insulin (P < 0.001), homeostatic model of assessment-insulin resistance (P < 0.001), leptin (P < 0.001), total amylin (P = 0.03), GIP (P = 0.01), PP (P = 0.02) and increased adiponectin (P < 0.001). There was no significant difference in appetite sensations. CONCLUSIONS: Modest weight loss in obese adolescents leads to changes in some adipokines and gut hormones that may favour weight regain.