Hunger Module 37

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HungerModule 37
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The Physiology of Hunger

• Stomach contractions (pangs) send signals to the
  brain making us aware of our hunger.

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Stomachs Removed
Tsang (1938) removed rat stomachs connected the
esophagus to the small intestines and yet the
rats felt hungry (and ate food).
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Glucose C6H12O6

• Glucose level in the blood is maintained. Insulin
  decreases glucose in blood making us feel hungry.

Glucose Molecule
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Glucose Brain

• Levels of glucose in the blood are monitored by
  receptors (neurons) in the stomach, liver,
  intestines, they send signals to the hypothalamus
  in the brain.

Rat Hypothalamus
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Hypothalamic Centers
Lateral hypothalamus (LH) brings on hunger
(stimulation). Destroy it and the animal has no
interest in eating. Reduction of blood glucose
stimulates orexin in LH which leads to ravenous
eating in rats.
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Hypothalamic Centers
Ventromedial hypothalamus (VMH) depresses hunger
(stimulation). Destroy it and the animal eats
excessively.
Richard Howard
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Hypothalamus Hormones
Hypothalamus monitors a number of hormones
that are related to hunger.
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Set-Point Theory

• Manipulating lateral and ventromedial
  hypothalamus alters the bodys weight
  thermostat.

If weight is lost food intake increases and
energy expenditure decreases. If weight is gained
the opposite takes place.
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The Psychology of Hunger

• Memory plays an important role in hunger. Due to
  difficulties with retention, amnesia patients eat
  frequently, if given food (Rozin et al., 1998).

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Taste Preference Biology or Culture?

• Body chemistry and environmental factors together
  influence not only when we feel hunger but what
  we feel hungry for!

Richard Olsenius/ Black Star
Victor Englebert
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Hot Cultures like Hot Spices

• Countries with hot climates use more
  bacteria-inhibiting spices in meat dishes.

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When scientists put 36 conscientious objectors on
a semi-starvation diet for six months, all of the
following occurred EXCEPT

• A. the men appeared listless and apathetic.
• B. the men became obsessed with food.
• C. the men spent more time thinking about sex.
• D. the men lost interest in social activities.

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Lindsey is extremely afraid of becoming obese
even though she is underweight. She often checks
her body in the mirror for any signs of fat and
refuses to eat most foods because she insists
they are fatty or high in calories. Lindsey most
clearly demonstrates symptoms of

• A. excess PYY.
• B. bulimia nervosa.
• C. an abnormally high set point.
• D. anorexia nervosa.

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Eating Disorders

• Anorexia Nervosa Characterized by a
  normal-weight person (usually adolescent women)
  losing weight continuously and yet feeling
  overweight.

Reprinted by permission of The New England
Journal of Medicine, 207, (Oct 5, 1932), 613-617.
Lisa OConnor/ Zuma/ Corbis
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Eating Disorders

• Bulimia Nervosa A disorder characterized by
  episodes of overeating, usually of high-calorie
  foods, followed by vomiting, laxative use,
  fasting, or excessive exercise.

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Obesity

A disorder characterized by excessive overweight.
Obesity increases risk and health issues like
cardiovascular diseases, diabetes hypertension,
arthritis, and back problems.
http//www.cyberdiet.com
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Youve just gotten a job as a weight loss
counselor. Your first client wants you to tell
him some things he should consider when
approaching a weight loss regimen. Which of the
following statements is BAD advice?

• A. Weight loss and gain have genetic
  components.
• B. Weight loss is a simple matter of cutting
  down on calories.
• C. Social influences, such as daily routine and
  peers, have an effect on weight loss and gain.
• D. Exercise can be helpful for people who want
  to lose weight.

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Reasons for Eating Disorders

• Sexual Abuse Childhood sexual abuse does not
  cause eating disorders.
• Family Raised in a family where weight is
  excessive concern results in younger generation
  developing eating disorders.
• Genetics Twin studies have shown eating
  disorders are more likely to occur in identical
  than fraternal twins.

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Body Image (Women)

• Western culture tends to over-emphasize thin body
  image more than other cultures.