The Psychology of Eating: From Healthy to Disordered Behavior

52 Food Choice

perifornical hypothalamus. Research has found that if injected with

neuropeptide Y, rats who are already full will still consume large

amounts of food. It also appears to cause a preference for carbohydrates

(Leibowitz, 1986).

• Galanin: This is a 29-amino-acid peptide that is widespread in the brain
  but is particularly found in the paraventricular hypothalamus. Injections
  of galanin into rats cause an increase in food intake and a preference
  for fats rather than carbohydrates (Leibowitz, 1986).

Neurotransmitters and modulators that decrease food intake
A number of neurotransmitters decrease food intake (Rowland et al., 2001):

• Cholecystokinin (CCK): This endogenous 33-amino-acid peptide is
  released into the bloodstream during meals and is widespread in the
  brain. If injected into rats, CCK causes a reduction in appetite and
  satiation. It also suppresses weight gain.


• Bombesin: This peptide has been shown to reduce food intake in rats.


• Corticotropin-releasing hormone (CRH): This is a 41-amino-acid
  peptide produced in the paraventricular hypothalamus and a number
  of other brain sites. It has been shown to reduce food intake.


• Serotonin (5HT): Serotonin, or 5HT, is a neurotransmitter which has
  also been shown to decrease food intake.

Neurotransmitters therefore seem to function by either increasing or
decreasing food intake. The role of neurotransmitters has also been
investigated through research on the impact of drugs on eating behavior.

Psychopharmacological drugs and neurochemicals

The study of the impact of drugs on food choice provides a means to
further understand the neurochemical basis for hunger and satiety
(Blundell, Hill, and Lawton, 1989). Most of this research has been carried
out on animals in the laboratory; only some has been carried out on humans.
The effects of drugs on hunger will now be considered along with how these
drug effects are linked to the neurotransmitters:

• Nicotinedecreases food intake, and smokers generally weigh about
  3 kg (7 lbs) less than nonsmokers (US Department of Health and Human
  Services, 1990). According to Ogden and Fox (1994), some dieters use