The Psychology of Eating: From Healthy to Disordered Behavior

54 Food Choice

of our brain and how this chemical activity in turn relates to eating behav-
ior. It has been suggested that there are three basic pathways – the cate-
cholamine, serotonin, and peptide pathways – that influence eating behavior
as follows (Blundell et al., 1989; and see figure 3.5):

• The serotonin pathways influence the feelings of fullness (known as
  satiety) during a meal, thereby causing the person to stop eating.


• Catecholamines influence satiety between meals, thereby triggering
  hunger and determining the intervals between eating.


• Peptides appear to influence the reward and pleasurable (sometimes
  referred to as hedonic) properties of food.

The drugs mentioned above influence these pathways as follows:

• Amphetamine, amitryptiline, and other tricyclics influence the cate-
  cholamine pathway.


• The SSRIs, fenfluoramine, and tryptophan influence the serotonin
  pathway.


• CCK, naloxone, and morphine are peptides and influence the pleasure
  associated with eating food.

Some drugs have nonspecific effects, including chlorpromazine and lithium,
which influence both the catecholamine and serotonin pathways, and others,
such as nicotine and marijuana, appear to have more generalized effects.
Therefore, the drugs which have been shown to influence hunger and
weight gain provide insights into the physiology of hunger and satiety and

Catecholamine

pathway

Serotonin

pathway

Peptides

Between-meal

satiety

Within-meal

fullness

Pleasure of

eating

Hunger/satiety

Figure 3.5 Neurochemicals and food choice.