Satiety

Satiety is the sensation of fullness that emerges after eating and persists for a period, reducing the motivation to start or continue eating until a person experiences hunger again. It is distinct from satiation, the process that rapidly terminates a meal, and from hunger, the feeling that drives the initiation of eating. Together, satiation and satiety regulate meal size and the intervals between meals.

Physiologically, satiety involves signals from the gastrointestinal tract, the pancreas, and adipose tissue that communicate with brain centers. Hormones such as cholecystokinin, peptide YY, glucagon-like peptide-1, and insulin contribute to feelings of fullness, while ghrelin rises before meals to promote hunger. Gastric distension and the mechanical stretch of the stomach also influence satiety signals via vagal pathways to the brain. Central nervous system regions, including the hypothalamus and brainstem, integrate these signals with reward and memory circuits to modulate appetite and eating behavior.

Measurement of satiety commonly relies on subjective scales to rate fullness, as well as behavioral measures such as subsequent energy intake after a test meal. Researchers also use constructs like the satiety index or satiety quotient to compare how different foods influence fullness per calorie. Factors affecting satiety include macronutrient composition (protein and fiber tend to enhance fullness), energy density, food volume, palatability, and meal timing or regularity.

Clinical relevance centers on weight management and appetite disorders. Understanding satiety can inform dietary strategies—higher-protein or higher-fiber meals, greater volume with low energy density, and regular eating patterns—to support reduced energy intake and sustainable weight control.