Eating Slowly Boosts Appetite-Suppressing GLP-1 and PYY in Obese Teens But Not in Obese Adults

What the researchers found

Fast eating did not stimulate GLP-1 release in either age group, while slow eating increased circulating GLP-1 only in obese adolescents. PYY increased after both fast and slow eating in both groups, but slow eating was significantly more effective at stimulating PYY release in obese adolescents compared to adults.

Slow eating evoked higher satiety only in obese adolescents, with reduced hunger at 210 minutes. Obese adults showed no significant differences in satiety or hunger between eating rates. Postprandial insulin and triglyceride responses were higher in obese adults than adolescents regardless of eating speed, reflecting greater metabolic dysregulation with age and prolonged obesity.

Why it matters

This study reveals that the body's natural appetite-suppressing peptide response to slow eating degrades with age and prolonged obesity. For obese teens, simply eating more slowly may boost the very same gut peptides (GLP-1 and PYY) that pharmaceutical drugs target. The loss of this response in adults suggests that early intervention for obesity may be critical before the gut's regulatory mechanisms become impaired.

How the study worked

Crossover study design where 18 obese adolescents and adults each consumed the same test meal on two sessions — in 5 minutes (fast) or 30 minutes (slow). Blood was drawn over 210 minutes to measure GLP-1, PYY, glucose, insulin, and triglycerides. Visual analog scales assessed subjective hunger and satiety at multiple time points.

What this study cannot tell us

The sample size of 18 subjects is small, limiting statistical power and generalizability. Only one meal type (ice cream) was tested, which may not represent typical diets. The study compared adolescents and adults but could not separate the effects of age from duration of obesity. The crossover design is a strength, but the short-term nature doesn't show whether habitual slow eating produces lasting effects.

How to read the evidence

This is a small crossover study with 18 participants, providing within-subject comparisons but limited by sample size. The crossover design adds rigor, but replication in larger cohorts is needed.

When this study was published

Published in 2013, this study preceded the GLP-1 drug revolution but remains relevant for understanding the natural physiology of appetite-regulating peptides and how obesity impairs them.

The bigger picture

This finding connects eating behavior, gut peptide physiology, and the progressive nature of obesity. GLP-1 and PYY are the same peptides targeted by blockbuster weight-loss drugs. The fact that a simple behavioral change (eating slowly) can naturally boost these peptides in younger individuals — but not in adults with longstanding obesity — illustrates how obesity may fundamentally alter gut-brain signaling over time.

Questions still open

• Can the gut peptide response to slow eating be restored in obese adults through sustained dietary intervention or weight loss?
• Would combining slow eating with GLP-1 agonist therapy produce additive benefits in obese adolescents?
• What biological mechanism causes the loss of eating-speed-dependent GLP-1 release in obese adults?

Common questions

Read the original research

Anorexigenic postprandial responses of PYY and GLP1 to slow ice cream consumption: preservation in obese adolescents, but not in obese adults.

European journal of endocrinology, 168(3), 429-36

Citation

Rigamonti, A E; Agosti, F; Compri, E; Giunta, M; Marazzi, N; Muller, E E; Cella, S G; Sartorio, A. (2013). Anorexigenic postprandial responses of PYY and GLP1 to slow ice cream consumption: preservation in obese adolescents, but not in obese adults.. European journal of endocrinology, 168(3), 429-36. https://doi.org/10.1530/EJE-12-0867