Understanding Psychology (10th Ed)

obesity
Body weight that is more than 
20% above the average weight for a 
person of a particular height.
 Key Concepts 
What biological and social 
factors underlie hunger? 
How are needs relating to 
achievement, affi
liation, and 
power motivation exhibited?
M O D U L E 3 0
Human Needs and Motivation: 
Eat, Drink, and Be Daring
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318 Chapter 
10 
Motivation and Emotion
relatively recent view. In 19 th century Hawaii, the most attractive women were those 
who were the heaviest. Furthermore, for most of the 20 th century—except for periods 
in the 1920s and the most recent decades—the ideal female fi gure was relatively full. 
Even today, weight standards differ among different cultural groups. For instance, in 
some traditional Arab cultures, obese women are so prized as wives that parents 
force-feed their female children to make them more desirable (Naik, 2004; Blixen,
Singh, & Xu, 2006; Marsh, Hau, & Sung, 2007). 
Regardless of cultural standards for appearance and weight, no one doubts that 
being overweight represents a major health risk. However, controlling weight is com-
plicated because eating behavior involves a variety of mechanisms. In our discussion 
of what motivates people to eat, we’ll start with the biological aspects of eating.
 BIOLOGICAL FACTORS IN 
THE REGULATION OF HUNGER 
In contrast to human beings, other species are unlikely to 
become obese. Internal mechanisms regulate not only the quan-
tity of food they take in, but also the kind of food they desire. 
For example, rats that have been deprived of particular foods 
seek out alternatives that contain the specifi c nutrients their diet 
is lacking, and many species, given the choice of a wide variety 
of foods, select a well-balanced diet (Bouchard & Bray, 1996; 
Woods et al., 2000; Jones & Corp, 2003). 
Complex biological mechanisms tell organisms whether they 
require food or should stop eating. It’s not just a matter of an 
empty stomach causing hunger pangs and a full one alleviating 
those pangs. (Even individuals who have had their stomachs 
removed still experience the sensation of hunger.) One important