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LECTURE OVERVIEWWHY DO WE EAT?
WHY DOES EATING BECOME DISORDERED?
PSYCHOSOCIAL AND BIOLOGICAL FACTORS
OBESITY, ANOREXIA, BULLIMIA
©John Wiley & Sons, Inc. 2010
Why is eating so complicated?
Eating is a motivated behavior, yet it is also confused with emotion and
can become disordered.
©John Wiley & Sons, Inc. 2010
1. Eating to reduce hunger is a good example of the drive theory of motivation.
2. But the arousal theory of motivation explains why we might eat a slice of pumpkin pie after consuming a heavy holiday dinner i.e. stimulation seeking.
©John Wiley & Sons, Inc. 2010
• Cannon & Washburn’s early technique for measuring internal factors in hunger
©John Wiley & Sons, Inc. 2010
Hunger and Eating
Psychosocial Theories for why eating becomes disordered
• Incentive: motivation results from the “pull” of external environmental stimuli
• Cognitive: motivation affected by attributions & expectations
.
©John Wiley & S
Psychosocial Theories for why eating becomes disordered (cont.)
Behavioral: unhelpfullearned associations
Analytical: expression of inner conflict
©John Wiley & Sons, Inc. 2010
Hunger and Eating
• Biological factors: stomach, biochemistry, the brain
• Note the size difference in these rats. The rat on the left had the ventromedial area of its hypothalamus destroyed, the one on the right had
• the lateral hypo.removed.©John Wiley & Sons, Inc. 2010
CHEMISTRY OF EATING?
• Is the ventromedial hypothalamus a satiety center? Is the lateral hypothalamus an eating center?
• Leptin is the hormone that signals satiety in the brain.
• Ghrelin is the hormone that signals hunger in the brain.
©John Wiley & Sons, Inc. 2010
Hunger and Eating• Psychological factors:
visual cues, cultural conditioning
• Or Genetic: Obesity is more common in Pima Indians living in U.S., but not for those in nearby Mexico with traditional diet.
©John Wiley & Sons, Inc. 2010
Is Obesity a Psychological Issue?
• Obesity results from numerous biological and psychosocial factors.
BMI > 30
©John Wiley & Sons, Inc. 2010
©John Wiley & Sons, Inc. 2010
• Anorexia nervosa & bulimia nervosa are both characterized by an overwhelming fear of becoming obese & explained by multiple biological & psychosocial factors.