Eating Disorders

305
Eating
Celebrations, holidays, vacations, and even daily family interactions often revolve
around food and what some call a food culture (Rozin, 1996). There are wide cultural
variations in food use and selection. For example, chewing coca leaves is popular in
the Bolivian highlands but illegal in the United States (Burchard, 1992). Insects called
palm weevils, a delicacy for people in Papua New Guinea (Paoletti, 1995), are regarded
by many Westerners as disgusting (Springer & Belk, 1994), and the beef enjoyed by
many Westerners is morally repugnant to devout Hindus in India. Even within the
same culture, different groups may have sharply contrasting food traditions. Squirrel
brains won’t be found on most dinner tables in the United States, but some people in
the rural South consider them to be a tasty treat. In short, eating serves functions
beyond nutrition—functions that help to remind us of who we are and with whom
we identify.
Eating Disorders
Problems in the processes that regulate hunger and eating may cause an eating disorder. The most common and dangerous examples are obesity, anorexia nervosa, and
bulimia nervosa.
´
BON APPETIT!
The definition
of
delicacy
differs from
by
culture to culture. At this elegant restaurant in Mexico, diners pay to
feast on baby alligators, insects, and
other dishes that some people from other
cultures would not eat even if the restaurant paid them. To appreciate your own
food culture, make a list of foods that are
traditionally valued by your family or cultural group but that people from other
groups do not, or might even be unwilling to, eat.
doing
2
learn
obesity A condition in which a person
is severely overweight.
The World Health Organization (WHO, 1998) defines obesity as a condition in which a person’s body-mass index, or BMI, is greater than 30. BMI is determined by dividing a person’s weight (in kilograms) by the square of the person’s height
(in meters). So someone who is 5 feet 2 inches and weighs 164 pounds would be classified as obese, as would someone 5 feet 10 inches who weighs 207 pounds. BMI calculators are available at web sites such as www.consumer.gov/weightloss/bmi.htm. People whose BMI is 25 to 29.9 are considered to be overweight, but not obese. (Keep in
mind, though, that a given volume of muscle weighs more than the same volume of
fat, so very muscular individuals may have an elevated BMI without being overweight.)
Using the BMI criterion, about 32 percent of adults in the United States are obese and
about 17 percent of children are overweight (Flegal et al., 2002; Hedley et al., 2004;
Mokdad et al., 2003; Ogden et al., 2006). The problem has become so common that
commercial jets have to burn excess fuel to carry heavier loads, parents of obese young
children have trouble finding car safety seats to fit them, and the funeral industry has
to offer larger than normal coffins and order wider hearses (Dannenberg, Burton, &
Jackson, 2004; St. John, 2003; Trifiletti et al., 2006). And obesity among adults and children is rising, not only in the United States but also in regions as diverse as Asia,
Europe, South America, and Africa (e.g., Hedley et al., 2004; Manson et al., 2004;
McCarthy, Ellis, & Cole, 2003; Rolland-Cachera et al., 2002; Sturm, 2003; Vasan et al.,
2005; Wang & Lobstein, 2006; WHO, 2002a). Obesity is associated with health problems such as diabetes, high blood pressure, an increased risk of heart attack, and possibly Alzheimer’s disease (Gustafson et al., 2003; Lakdawalla, Bhattacharya, & Goldman,
2004; Nanchahal et al., 2005). In the United States alone, obesity is blamed for about
30,000 deaths each year and for a predicted shortening of life expectancy in the twentyfirst century (Flegel et al., 2005; Olshansky et al., 2005).
Why do some people become obese? Body weight is determined by a combination of food intake and energy output (Keesey & Powley, 1986). Obese people get
more energy from food than their body metabolizes, or “burns up.” The excess energy,
measured in calories, is stored as fat. Obese people tend to eat above-average amounts
of high-calorie, tasty foods but below-average amounts of less tasty foods (Kauffman,
Herman, & Polivy, 1995). Further, they may be less active than lean people, a pattern that often begins in childhood (Jago et al., 2005; Marshall et al., 2004; Strauss &
Pollack, 2001). Spending long hours watching television or playing computer games
is a major cause of the inactivity seen in overweight children (Hancox & Poulton,
2006).
In short, inadequate physical activity, combined with overeating—especially of the
high-fat foods so prevalent in most Western cultures—has a lot to do with obesity.
Obesity
306
Chapter 8 Motivation and Emotion
But not everyone who is inactive and eats a high-fat diet becomes obese, and some obese
people are as active as lean people, so other factors must also be involved (Blundell &
Cooling, 2000; Parsons, Power, & Manor, 2005). Some people probably have a genetic
predisposition toward obesity (Farooqi & O’Rahilly, 2004; Loos et al., 2006; Meyre et al.,
2005). For example, although most obese people have the genes to make leptin, they
may not be sensitive to its weight-suppressing effects—perhaps because of differing
genetic codes for leptin receptors in the hypothalamus. These genetic factors, along with
the presence of certain viruses in the body (Dhurandhar et al., 2000), may help explain
obese people’s tendency to eat more, to accumulate fat, and to feel hungrier than lean
people.
Other explanations for obesity focus on factors such as learning from the examples set
by parents who overeat (Hood et al., 2000), too little parental control over what and how
much children eat (Johnson & Birch, 1994), and maladaptive reactions to stress. Many
people do tend to eat more when under stress, a reaction that may be especially extreme
among those who become obese (Dallman et al., 2003; Friedman & Brownell, 1995).
For most people, and especially for people who are obese, it is a lot easier to gain
weight than to lose it and keep it off (Jain, 2005; McTigue et al., 2003). The problem
arises partly because our evolutionary ancestors—like nonhuman animals in the wild
today—could not always be sure that food would be available. Those who survived
lean times were the ones whose genes created tendencies to build and maintain fat
reserves (e.g., Hara et al., 2000). These “thrifty genes” are adaptive in famine-plagued
environments, but they can be harmful and even deadly in affluent societies in which
overeating is unnecessary and in which donut shops and fast food restaurants are on
every corner (Brown, 1991). Further, if people starve themselves to lose weight, their
bodies may burn calories more slowly. This drop in metabolism saves energy and fat
reserves and slows weight loss (Leibel, Rosenbaum, & Hirsch, 1995). No wonder health
and nutrition experts warn that obese people (and others) should not try to lose a
great deal of weight quickly by dramatically cutting food intake (Brownell & Rodin,
1994).
An even more radical approach to the problem of obesity is bariatric surgery
(Hamad, 2004), which restructures the stomach and intestines so that less food energy
is absorbed and stored. Bariatric surgery was performed on about 103,000 people in
2003 alone (Santry, Gillen, & Lauderdale, 2005). Its popularity has been fueled partly
by the examples of NBC-TV personality Al Roker and other celebrities whose surgery
resulted in dramatic weight loss. Still, due to its costs and risks—postoperative mortality rates range from 0.1 to 2 percent—bariatric surgery is recommended only for
extreme and life-threatening cases of obesity.
Drugs offer yet another approach. Several antiobesity drugs have been developed,
including one that prevents fat in foods from being digested (e.g., Finer et al., 2000;
Hauptman et al., 2000). Another drug has been found to interfere with an enzyme that
forms fat. This “fatty acid synthase inhibitor” not only caused rapid weight loss in mice
but also reduced their hunger (Loftus et al., 2000). The drug has not yet been tested
for safety and effectiveness in humans, but researchers hope that it may someday be
possible to give obese people medications that alter the brain mechanisms involved in
overeating and fat storage (Arterburn, Crane, & Veenstra, 2004; Chanoine et al., 2005;
Wynne et al., 2005).
Millions of people are taking various kinds of antiobesity medication (Stafford &
Radley, 2003), but drug treatments alone are unlikely to solve the problem of obesity.
In fact, no single antiobesity treatment is likely to be a safe, effective solution that works
for everyone. To achieve the kind of gradual weight loss that is most likely to last, obese
people are advised to make lifestyle changes in addition to, or instead of, drugs or surgery. The most effective weight-loss programs include components designed to reduce
food intake, to change eating habits and attitudes toward food, and to increase energy
expenditure through regular exercise (Bray & Tartaglia, 2000; Stice & Shaw, 2004;
Wadden et al., 2001). Exercise is especially important because it burns calories while
raising metabolism rather than lowering it (Binzen, Swan, & Manore, 2001; Curioni &
Lourenço, 2005; Wadden et al., 2005).
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Eating
Anorexia Nervosa At the opposite extreme of eating disorders is anorexia nervosa (pronounced “ann-or-EX-ee-ah nuhr-VO-suh”). It is characterized by some com-
THIN IS IN In Western cultures today,
thinness is a much-sought-after ideal, especially among young women. This ideal
is seen in fashion models, as well as in
Miss America pageant winners, whose
body mass index has decreased from the
“normal” range of 20 to 25 in the 1920s
to an “undernourished” 18.5 in recent
years (Rubinstein & Caballero, 2000; Voracek & Fisher, 2002). In the United States,
35 percent of normal-weight girls—and
12 percent of underweight girls!—begin
dieting when they are as young as nine
or ten. Correlational studies suggest that
many of these children’s efforts to lose
weight may have come in response to
criticism from family members (Barr
Taylor et al., 2006a; Schreiber et al., 1996);
for some, the result is anorexia.
anorexia nervosa An eating disorder
characterized by self-starvation and
dramatic weight loss.
bulimia nervosa An eating disorder
that involves eating massive quantities
of food, then eliminating it by selfinduced vomiting or laxatives.
bination of self-starvation, self-induced vomiting, excessive exercise, and laxative use
that results in weight loss to below 85 percent of normal (Kaye et al., 2000). About 95 percent of people who suffer from anorexia are young females. Anorexics often feel hungry, and many are obsessed with food and its preparation, yet they refuse to eat.
Anorexic self-starvation causes serious, often irreversible, physical damage, including
reduction in bone density that increases the risk of fractures (Grinspoon et al., 2000).
The health dangers may be especially high in anorexic dancers, gymnasts, and other
female athletes, who are at risk for stress fractures and heart problems (Sherman &
Thompson, 2004). It is estimated that from 4 to 30 percent of those suffering severe
anorexia eventually die of starvation, biochemical imbalances, or suicide; their death
rate is twelve times higher than for other young women (Herzog et al., 2000; Millar
et al., 2005; National Association of Anorexia Nervosa and Associated Disorders, 2002).
Anorexia tends to first appear in adolescence and affects about 1 percent of young
women in the United States. It is also a growing problem in many other industrialized
nations (American Psychiatric Association Work Group on Eating Disorders, 2000;
Bulik et al., 2006; Rome et al., 2003).
The appearance of anorexia has been attributed to a combination of factors, including genetic predispositions, biochemical imbalances, social influences, and psychological characteristics (Bulik et al., 2000, 2006; Jacobi et al., 2004; Kaye et al., 2000; Keel &
Klump, 2003; Ribases et al., 2005; Vink et al., 2001). Psychological factors that may contribute to the problem include a self-punishing, perfectionistic personality and a culturally reinforced obsession with thinness and attractiveness (Bulik et al., 2003; Dittmar,
Halliwell, & Ive, 2006; Francis & Birch, 2005; Moradi, Dirks, & Matteson, 2005;
Ricciardelli & McCabe, 2004). Anorexics appear to develop a fear of being fat, which
they take to dangerous extremes (de Castro & Goldstein, 1995). Many anorexics continue to view themselves as fat or misshapen even as they are wasting away (Feingold &
Mazzella, 1998).
Drugs, hospitalization, and psychotherapy are all used to treat anorexia. In many
cases, treatment brings recovery and the maintenance of normal weight (National Institutes of Health, 2001; Pike et al., 2003), but more effective treatment and early intervention methods are still needed (Agras et al., 2004; Lo et al., 2003). Prevention programs now being tested with college women at high risk for developing anorexia are
showing promising results (e.g., Barr Taylor et al., 2006b; Franko et al., 2005).
Like anorexia, bulimia nervosa (pronounced “bu-LEE-mee-uh
nuhr-VO-suh”) involves intense fear of being fat, but the person may be thin, normal
in weight, or even overweight. Bulimia nervosa involves eating huge amounts of food
(say, several boxes of cookies, a half-gallon of ice cream, and a bucket of fried chicken)
and then getting rid of the food through self-induced vomiting or strong laxatives.
These “binge-purge” episodes may occur as often as twice a day (Weltzin et al., 1995).
Like people with anorexia, bulimic individuals are usually female; and, like anorexia,
bulimia usually begins with a desire to be slender. However, bulimia and anorexia are
separate disorders (Pryor, 1995). For one thing, most bulimics see their eating habits
as problematic, whereas most anorexics do not. In addition, bulimia nervosa is usually
not life threatening (Thompson, 1996). There are consequences, however, including
dehydration, nutritional problems, and intestinal damage. Many bulimics develop dental problems from the acids associated with vomiting. Frequent vomiting and the insertion of objects to cause it can also damage the throat.
Estimates of the frequency of bulimia in the United States range from 1 to 3 percent
of adolescent and college-age women (National Institutes of Health, 2001; U.S. Surgeon
General, 1999). The combination of factors that contribute to bulimia includes perfectionism, low self-esteem, stress, culturally encouraged preoccupation with being thin,
and depression and other emotional problems. Problems in the brain’s satiety mechanisms may also be involved (Crowther et al., 2001; Steiger et al., 2001; Stice, 2001; Stice &
Fairburn, 2003; Zalta & Keel, 2006). Treatment for bulimia, which typically includes
Bulimia Nervosa