Obese Children Show Blunted Ghrelin and PYY Appetite Peptide Responses After Eating | Research

The takeaway

Obese children have weakened ghrelin and peptide YY responses after meals compared to healthy-weight children, suggesting impaired appetite peptide signaling contributes to childhood obesity.

Blunted at both 60 and 120 minutes
Both ghrelin and PYY responses were significantly attenuated in obese children at 1 hour and 2 hours after eating, indicating a sustained impairment in appetite peptide signaling that persists well beyond the meal.

What the researchers found

Obese children showed attenuated postprandial ghrelin and peptide YY (PYY) responses compared to healthy-weight children. Ghrelin normally drops after eating (signaling fullness), but this drop was blunted in obese children at both 60 and 120 minutes (p<0.05 for both). Similarly, PYY normally rises after eating (promoting satiety), but this rise was reduced in obese children at both time points. These altered peptide hormone responses suggest a physiological basis for impaired appetite regulation in childhood obesity.

Why it matters

Childhood obesity affects over 340 million children worldwide. This meta-analysis reveals that obese children have blunted responses in two key appetite-regulating peptides after meals — their bodies don't properly signal fullness. This suggests that treating childhood obesity may require approaches that address these hormonal imbalances, potentially including peptide-based therapies that restore normal ghrelin and PYY signaling.

The numbers in context

9 studies · 32 test meal-hormone comparisons · 6 appetite hormones reviewed · ghrelin attenuated at 60 min (n=129) and 120 min (n=100) · PYY attenuated at 60 min (n=128) and 120 min (n=100) · all p<0.05 · 1,001 papers initially screened

How the study worked

Systematic review and meta-analysis searching EMBASE, CINAHL Plus, OVID Medline, and Cochrane Library. Nine studies meeting inclusion criteria were analyzed, collectively reporting on six appetite hormones across 32 test meal-hormone comparisons. Meta-analyses compared pooled mean differences in postprandial ghrelin and PYY changes between obese and healthy-weight children.

Who was studied

Obese and healthy-weight children from 9 studies measuring postprandial appetite hormone responses

What this study cannot tell us

Only 9 studies met inclusion criteria, with relatively small combined sample sizes (100-129 participants per analysis). Insufficient studies reported on hormones beyond ghrelin and PYY, preventing meta-analysis of GLP-1, CCK, and others. The studies varied in meal composition and hormone measurement methods. Behavioral and clinical outcomes (actual food intake, weight trajectories) were not assessed in relation to the hormonal findings.

How to read the evidence

This is a systematic review and meta-analysis — the highest level of evidence synthesis. However, it is limited by the small number of included studies (9) and relatively small participant numbers (100-129 per analysis), which reduces the certainty of the conclusions.

When this study was published

Published in 2016, this meta-analysis identified a significant gap in knowledge about appetite hormones in childhood obesity. Since then, research has expanded, particularly with the approval of GLP-1 drugs for adolescent obesity.

The bigger picture

This study provides evidence that childhood obesity has a physiological component involving impaired appetite peptide signaling — it's not simply about willpower or poor food choices. As GLP-1 receptor agonists are now being approved for adolescent obesity treatment, understanding the broader landscape of appetite peptide dysregulation in young people becomes increasingly important for developing comprehensive treatment strategies.

Questions still open

Could GLP-1 receptor agonists or other peptide-based therapies restore normal appetite hormone signaling in obese children?
Do the blunted ghrelin and PYY responses cause obesity, or does obesity cause the blunted responses — or is it a vicious cycle?
Would weight loss normalize ghrelin and PYY responses in obese children, or are the differences persistent?

Common questions

What do ghrelin and PYY normally do after we eat?

Ghrelin is the 'hunger hormone' — it's high before meals and drops after eating, signaling that you've had enough. PYY (peptide YY) does the opposite — it's released by the gut after eating and signals fullness to the brain. Together, they form part of the body's natural appetite control system. In obese children, both signals are weaker, meaning the body is less effective at recognizing that enough food has been eaten.

Does this mean obese children can't help overeating?

It means obese children may genuinely experience less fullness after meals due to weakened peptide hormone signals. This isn't about willpower — it's a measurable physiological difference. Understanding this can help shift approaches to childhood obesity from blame-based strategies to ones that address the underlying hormonal biology, such as meal timing strategies or potentially peptide-based treatments.

Read the original research

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

International journal of obesity (2005), 40(4), 555-63

View on PubMed ↗Publisher’s paper ↗

Citation

Nguo, K; Walker, K Z; Bonham, M P; Huggins, C E. (2016). Systematic review and meta-analysis of the effect of meal intake on postprandial appetite-related gastrointestinal hormones in obese children.. International journal of obesity (2005), 40(4), 555-63. https://doi.org/10.1038/ijo.2015.256