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About the value of controlling appetite • NutrInsight
The satiety cascade
The physiological need to eat can be linked to the satiating potential of foods, associated with their ability to suppress hunger and prevent any further intake of food (11;12). The perception of foods and how they are processed by the biological system generate endocrine and nervous signals that control appetite. Satiation and satiety occur even when only a small proportion of the nutrients ingested can have been absorbed and reached the cells.
Foods produce their satietogenic effect as a result of a series of anticipatory sensory, cognitive, pre-absorptive and post-absorptive processes. This series of processes has been designated the “satiety cascade” (Figure 3) (10;13).
Texture Visual Appearance
carbohydrate protein fat dietary fibre
Meal
Profile of hunger motivation
Satiation
Satiety Cascade
Inhibition of further food Intake
Hunger sensations
Satiety
Factors terminating meal
early
ONSET OF NEXT MEAL
Size and composition determined
by complex network of neural, humoral
and environmental factors
strong – weak
Late
Satiation
Sensory
Cognitive
Pre-absortive
Post-absorptive
Figure 3: Satiety cascade
Foods trigger the «satiety cascade», a series of four processes (sensory, cognitive, pre-absorptive and post-absorptive) that continue to inhibit hunger and eating throughout the period of satiety (13).
Sensory mechanisms are mainly induced by the senses of sight and smell, which can induce physiological signals even before the food has been ingested (the cephalic phase that makes it possible to anticipate the ingestion of foods). Then taste, temperature and texture of the foods contribute. These sensory characteristics of the food determine its palatability (how enjoyable it is), which plays an important role in determining how much food is consumed. Eating is more likely to be prolonged and, in the end, increased if foods are palatable, whereas it stops earlier if the sensation is not enjoyable.
The mechanisms of a cognitive order involve parameters such as the beliefs or expectations of individuals with regard to the properties of the foods consumed (which are themselves based on previous experience), and their voluntary control of the quantities eaten (degree of food restriction, dieting).
The pre-absorptive mechanisms start in the digestive tract before the nutrients are absorbed from the intestine, and most of them are linked to several different phenomena. The best known of these are the degree of gastric filling and distension (14), resulting from the arrival of food, which lead to satiation and contribute to the early onset of satiety via the stimulation of the vagal mechanoreceptors located in the stomach wall (15). Subsequently, once the food has reached the intestine it stimulates the secretion by the cells in the stomach and intestine of various hormones or peptides, some of which reduce food intake (for instance, CCK, enterostatin, GLP-1 and PYY) and others that inhibit the secretion of hormones that stimulate eating (such as ghrelin, for instance - see paragraph 2.3 ). The substances produced by the digestion of food (amino acids, fatty acids, glucose, etc.) also regulate the appetite, notably via stimulation of vagal chemoreceptors located in the intestinal wall (15;16).
Mouthfeel Micronutriments
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Cephalic phase stimulation
Aroma – Taste