Hunger and the Brain

A strictly physiological analysis claims that an individual’s responses to hunger
are caused by the brain’s regulation of body weight. If the body goes below its predetermined “set point,” internal hunger cues are initiated to signal
the need for food consumption. External restraints, such as attempts to
live up to ideal cultural thinness standards, also affect behavior and may result
in restrained eating in order to maintain a body weight below the body’s
defined set point.

The idea of a body set point is rooted in the work of physiologist Claude
Bernard (1813-1878), a pioneer in research based on the concept of homeostasis,
or system balance in the body. Homeostasis has played a fundamental
role in many subsequent investigations regarding the physiology of hunger
and the regulatory systems involved in hunger satisfaction. Inherent in the
set-point theory is the concept of motivation, meaning that an organism is
driven physiologically and behaviorally toward maintenance of homeostasis
and the body’s set point and will adapt to accommodate the systems involved
in maintenance.
In addition, there appear to be two anatomically and behaviorally distinct
centers located in the hypothalamus, one regulating hunger and the other
regulating satiety. The area of the hypothalamus responsible for stimulating
eating behavior is the lateral hypothalamus. The ventromedial hypothalamus
is the area responsible for signaling the organism to stop eating. The lateral hypothalamus is responsible for establishing a set point for body
weight.

In comparing hunger and satiety sensation differences, increased hunger
and disturbed satiety appear to be two different and quite separate
mechanisms. Imbalance or dysfunction of either the hunger mechanism or
the satiety sensation can lead to obesity, overeating, binge eating, and other
eating disorders. It appears that the way hunger is experienced accounts, in
part, for its recognition. Whether hunger is experienced in context with
other drives or becomes a compulsive force that dominates all other drives
in life is a complex issue.

The prevalence of eating disorders and the multitude of variables associated
with hunger drives and regulation have provided psychologists with an
opportunity to examine the ways in which hunger might take on different
meanings. To a person who is anorexic, for example, hunger may be a positive
feeling—a state of being “high” and thus a goal to seek. To others, hunger
may produce feelings of anxiety, insecurity, or anger. In this case, a person
might eat before feeling hunger to prevent the feelings from arising.
People’s ability to experience hunger in different ways provides psychologists
with two types of hunger, which are commonly referred to as hunger
and appetite.

Hunger and appetite are not the same. Actual physical need is the basis of
true hunger, while appetite can be triggered by thought, feeling, or sensation.
Physical need can be separate from psychological need, although they
may feel the same to the person who is not conscious of the difference. Compulsive
eaters are often unable to recognize the difference between “real”
hunger and psychological hunger, or appetite. While psychological hunger
can be equally as motivating a need as stomach hunger, appetite (or mouth
hunger) is emotionally, cognitively, and psychologically based thus cannot
be fed in the same way. Stomach hunger can be satisfied by eating, whereas
“feeding” mouth hunger must involve other activities and behaviors, as food
does not ultimately seem to satisfy the mouth type of hunger.