Fast Eating Paradoxically Boosts Appetite-Suppressing Gut Peptides in Prader-Willi Syndrome | Research

The takeaway

Adults with Prader-Willi syndrome showed an unexpected reversal in gut peptide responses — fast eating produced higher GLP-1 and PYY levels and more satiety than slow eating.

Reversed peptide response
In Prader-Willi syndrome, fast eating (5 min) produced higher GLP-1 and PYY levels than slow eating (30 min) — the exact opposite of the pattern in healthy subjects

What the researchers found

In a surprising reversal of the normal pattern, fast eating (5 minutes) produced higher levels of the appetite-suppressing gut peptides GLP-1 and PYY in adults with Prader-Willi syndrome (PWS) compared to slow eating (30 minutes). In healthy normal-weight subjects, the expected opposite was true — slow eating produced greater peptide release and more satiety. In patients with simple obesity, neither eating rate significantly affected GLP-1 levels.

Fast eating also produced lower hunger and higher satiety ratings in PWS patients, mirroring the peptide findings. This reversed relationship suggests PWS involves a fundamentally different pathophysiological substrate governing gut-brain appetite signaling compared to simple obesity.

Why it matters

Prader-Willi syndrome is characterized by insatiable hunger (hyperphagia) and severe obesity. Understanding how gut appetite peptides respond differently in PWS versus simple obesity could reveal new therapeutic targets. The finding that fast eating paradoxically increases satiety peptides in PWS challenges conventional dietary advice to eat slowly, and suggests that the gut-brain axis dysfunction in PWS is qualitatively different from ordinary obesity — not just a more extreme version of it.

The numbers in context

Fast feeding: 5 min · Slow feeding: 30 min · 3 groups: PWS, simple obesity, normal weight · GLP-1 and PYY measured postprandially · PWS: fast eating → higher GLP-1, PYY, satiety

How the study worked

Three groups of adult participants — PWS patients, age-matched patients with simple obesity, and normal-weight subjects — consumed ice cream either quickly (5 minutes) or slowly (30 minutes). Blood levels of the anorexigenic (appetite-suppressing) gut peptides PYY and GLP-1 were measured after eating. Visual analog scales assessed subjective hunger and satiety feelings.

Who was studied

Adults with Prader-Willi syndrome, age-matched adults with simple obesity, and normal-weight controls

What this study cannot tell us

Sample sizes were not reported in the abstract and are likely small given the rarity of PWS. The ice cream stimulus is a single food type and may not represent typical meals. The study measured postprandial peptide responses but did not assess actual food intake or long-term weight effects. The mechanisms underlying the reversed eating rate response in PWS remain unexplained.

How to read the evidence

This is a controlled clinical study comparing three groups with two eating conditions. While the design is sound, the sample sizes are likely small due to the rarity of PWS. The surprising finding needs replication. Evidence strength is preliminary but intriguing.

When this study was published

Published in 2014, this remains a notable study in PWS peptide biology. More recent research on GLP-1 agonists in PWS may provide additional context for these findings.

The bigger picture

GLP-1 and PYY are two of the most important appetite-regulating peptides, and both are targets of current obesity drugs. Understanding why these peptides respond paradoxically in Prader-Willi syndrome could reveal fundamental insights about gut-brain appetite signaling. If PWS patients have a different gut peptide signaling architecture, therapies targeting GLP-1 and PYY pathways may need to be specifically adapted for this population. This study also challenges the universal dietary advice to 'eat slowly for better satiety' — showing that what works for most people may not apply to all conditions.

Questions still open

What mechanism causes fast eating to increase GLP-1 and PYY release in PWS when the opposite occurs in healthy subjects?
Could GLP-1 receptor agonists like semaglutide help manage hyperphagia in Prader-Willi syndrome given the altered GLP-1 response?
Does the paradoxical eating rate response in PWS persist across different food types and meal sizes?

Common questions

What are GLP-1 and PYY, and why do they matter for appetite?

GLP-1 (glucagon-like peptide-1) and PYY (peptide YY) are hormones released by the gut after eating that signal fullness to the brain. They're called 'anorexigenic' because they suppress appetite. GLP-1 is the same target that weight loss drugs like semaglutide activate. In healthy people, slow eating typically triggers more of these peptides, producing greater satiety.

What is Prader-Willi syndrome and why is appetite different?

Prader-Willi syndrome is a rare genetic condition caused by loss of genes on chromosome 15. It causes insatiable hunger (hyperphagia), leading to severe obesity if food intake isn't carefully managed. This study suggests the gut-brain appetite signaling system works fundamentally differently in PWS — not just as an extreme version of regular obesity, but as a qualitatively different condition.

Read the original research

Unexpectedly increased anorexigenic postprandial responses of PYY and GLP-1 to fast ice cream consumption in adult patients with Prader-Willi syndrome.

Clinical endocrinology, 81(4), 542-50

View on PubMed ↗Publisher’s paper ↗

Citation

Rigamonti, A E; Bini, S; Grugni, G; Agosti, F; De Col, A; Mallone, M; Cella, S G; Sartorio, A. (2014). Unexpectedly increased anorexigenic postprandial responses of PYY and GLP-1 to fast ice cream consumption in adult patients with Prader-Willi syndrome.. Clinical endocrinology, 81(4), 542-50. https://doi.org/10.1111/cen.12395