Motivation and Emotion 371(top) Cultural factors play an important
part in why people eat. Women in Japan
have been found to be motivated to eat
by hunger and social demands, illustrated
by the interaction during a meal at this
family gathering.
(bottom) Women in the United States may
eat because they are depressed or for
other emotional reasons rather than just
to appease hunger or as part of a social
situation. Obviously, this woman does
not need the social trappings of a bowl,
dining table, and the company of others
to motivate her eating habits—unless you
count the cat.to the way Pavlov’s dogs began salivating before they received their food). Like getting
hungry at a certain time of day, this physiological phenomenon may also be due to classi-
cal conditioning: In the past, eating foods with certain visual and sensory characteristics
led to an insulin spike, and this pairing occurred so frequently that now just looking
at or smelling the food produces the spike before the food is consumed (Stockhorst,
1999). This may explain why some people (who are called “externals” because of their
tendency to focus on the external features of food rather than internal hunger) are far
more responsive to these external signals—they produce far more insulin in response to
the anticipation of eating than do nonexternals, or people who are less affected by external
cues (Rodin, 1985).
Cultural factors and gender also play a part in determining hunger and eating hab-
its. In one study, a questionnaire about eating habits was given to both men and women
from the United States and Japan. Although no significant differences in what initiates
eating existed for men in either culture, women in the United States were found to be
much more likely to start eating for emotional reasons, such as depression. Japanese
women were more likely to eat because of hunger signals or social demands (Hawks
et al., 2003). In this same study, both men and women from the United States were more
likely to eat while watching television or movies than were Japanese men and women.
Both culture and gender must be taken into account when studying why and under what
circumstances people eat.
Obesity
9.7 Recognize some of the factors that contribute to obesity.
It would be nice if people all over the world ate just the amount of food that they needed
and were able to maintain a healthy, normal weight. Unfortunately, that is not the case
for many people. Some people weigh far more than they should, whereas others weigh
far less.
Several maladaptive eating problems, including anorexia nervosa, bulimia nervosa,
and binge-eating disorder, are classified as clinical (mental) disorders in the Diagnostic
and Statistical Manual of Mental Disorders, Fifth Edition, or DSM-5 (American Psychiatric
Association, 2013), which is a listing of disorders and their symptoms used by psycho-
logical professionals to make a diagnosis. These disorders are discussed in a later chap-
ter. to Learning Objective 14.11.
In this chapter, we look at the problem of obesity. Why do some people get so fat?
Is it just overeating?
There are several factors that contribute to obesity, a condition in which the body weight
of a person is 20 percent or more over the ideal body weight for that person’s height. Actual
definitions of obesity vary. Some definitions consider 20 to 30 percent to be overweight and
limit obesity to 30 percent or more. Others state that men are obese at 20 percent over the
ideal weight and women at 30 percent. However it is defined, a significant factor in obesity
is heredity. There appear to be several sets of genes, some on different chromosomes, that
influence a person’s likelihood of becoming obese (Barsh et al., 2000). If there is a history of
obesity in a particular family, each family member has a risk of becoming obese that is dou-
ble or triple the risk of people who do not have a family history of obesity (Bouchard, 1997).
Hormones also play a role, particularly leptin, which plays an important part in controlling
appetite. Problems with leptin production or detection can lead to overeating (Friedman &
Halaas, 1998), although this may not be the whole story. In a study in which leptin action was
blocked in both obese and nonobese mice, there were no differences between the two groups
in how much they ate or how much weight they gained, leading the researchers to conclude
that impaired leptin activity may not be as important a cause of obesity as previously thought
(Ottaway et al., 2015).
Certainly, another obesity factor is overeating. Around the world, as developing
countries build stronger economies and their food supplies become stable, the rates of