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About the value of controlling appetite • NutrInsight
Factors Three parameters
1 - Subjective appetite (or motivation to eat)
2 - Food intake
3 - Food preferences Food craving
interaction between biology and environment
Individual factors External factors
Figure 1: The main constituents of the appetite
Hunger, the main trigger for eating
The term “hunger” has been defined in various ways, which were summarized by Mattes in 1993 (6). He described «hunger» or «feeling hungry» as «subjective sensations experienced in the stomach, when one feels the need or desire to eat». The hunger known as «physiological» hunger includes the physiological and metabolic state linked to a lack of energy. It is defined by Mattes as a «sensation triggering eating behaviour under the control of numerous measurable neuro-hormonal mechanisms».
Fischler set out to define other types of hunger and therefore of «eaters» (7): whereas the «biological» eater eats to satisfy his/her «physiological» hunger, whereas the «social» eater is a person whose eating habits are influenced by the environment.
1.2 Appetite regulation and the satiety cascade
The role of satiation and satiety in appetite regulation
Satiation and satiety play key roles in regulating appetite, by modifying the eating-related motivations (or subjective sensations such as hunger, fullness) and food intake.
Satiation occurs during a meal; it leads the person to stop eating and therefore determines the amount of food consumed or the size of the meal. Satiation is characterised by the sensation of a full stomach resulting from the consumption of food and a reduced sensation of hunger.
Satiety determines the interval between two successive food intakes, characterised by the inhibition of the sensation of hunger after consuming food, until the next meal is triggered (associated with the reappearance of the sensation of hunger). It is generally accompanied by a sensation of a fullness and/or well-being.
In this way, satiation and satiety control the phenomena that occur during and between eating episodes. They act in concert to determine the components of eating behaviour and the motivation profile.
The glucostatic theory of the origin of hunger
In Man, a fall in blood sugar leads to an increase in the sensations of hunger, and a motivation to eat (6). Absolute concentrations of blood glucose do not seem to be important in the regulation of food intake. The transient and dynamic declines of blood glucose seem to be strongly related to meal initiation (8). The most convincing argument in favour of the glucostatic origin of the hunger signal resides essentially in the capacity of glucose, in certain tissues, to provide substrates for the production of adenosine triphosphate (ATP, a key factor in cell function). The brain contains glucosensitive neurones or glucose receptors, notably in the hypothalamus: this zone is particularly implicated in the neuro-homonal regulation of hunger and of satiety (9).
[ Appetite can be described as the internal motivation that leads a person
to look for food,to select it and to consume it. ]

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