The desire to eat, or appetite, is controlled by the appetite center of the brain, also known as the hypothalamus. The hypothalamus is influenced by a complex interaction of hormones, the
digestive tract, and the nervous system. If a person’s stomach is empty,
the blood sugar level decreases, and
a message goes to
the hypothalamus. When a person’s blood sugar is low, serotonin levels may also be low, and in addition to feeling hungry a person could feel irritable
and have a
heightened craving for foods that release serotonin, including
foods high in carbohydrates.
Foods high in carbohydrates include cake, cookies, and crackers that quickly break down into sugar available to the body for energy.As a result of low blood sugar levels and low serotonin, thehypothalamus is stimulated
and a person feels hunger. Once a person
has eaten enough, serotonin is produced, which creates a feel- ing of being full instead of a feeling
of hunger. An individual can easily associate a late afternoon slice of cake with these increased levels of serotonin and develop a habit that is dif-ficult to break.Stress, hormones,
and depression also affect levels of chem- icals in the body, such as serotonin, thus triggering the desire to eat. Some researchers, such as Dr. Judith Wurman, author of Managing Your Mind and Mood Through Food, believe that many obese people treat their “blah” feelings by indulging in carbohydrate-rich foods that boost their serotonin levels and therefore improve their mood, at least temporarily. This pat- tern of seeking out foods rich in carbohydrates to treat “blah”
feelings often leaves the individual feeling
worse as the body
floods the bloodstream with insulin and blood sugar levels dip, also know as a “sugar crash.” Despite the resulting sugar crash, the
pursuit of carbohydrate-rich foods is a difficult
habit to break for a person trying to boost his or her mood through food. The relationship
between cravings and serotonin levels encouraged the use of drugs, such as sibutramine, which boost serotonin levels to promote weight loss.Appetite, however, is not strictly driven by the quantity and timing of the most recent meal. A change in hormones,
for example, such as those associated with pregnancy, could increase appetite. Illness or stress could cause a decrease or increase
in appetite. Cortisol is a hormone that is secreted under stress. Women with higher levels of cortisol have been
found in research experiments to snack on higher-fat foods
than those with
lower cortisol levels. Cortisol
is just
one example of a hormone released by the body that influences eating habits.One
way to control the desire to eat is to alter the signaling system in
the brain that stimulates appetite. Neurotransmitters are chemicals in the brain that carry messages between the brain’s neurons. In the case of the neurotransmitter serotonin, this signaling system lets the body know
it is
full or hungry.
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