53-3 What are the three main eating disorders, and how do biological, psychological, and social-cultural influences make people more vulnerable to them?

Our bodies are naturally disposed to maintain a steady weight, including stored energy reserves for times when food becomes unavailable. But sometimes psychological influences overwhelm biological wisdom. This becomes painfully clear in three eating disorders.

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A U.S. National Institute of Mental Health-funded study reported that, at some point during their lifetime, 0.6 percent of the Americans studied had met the criteria for anorexia, 1 percent for bulimia, and 2.8 percent for binge-eating disorder (Hudson et al., 2007). So, how can we explain these disorders?

Eating disorders do not provide (as some have speculated) a telltale sign of childhood sexual abuse (Smolak & Murnen, 2002; Stice, 2002). The family environment may provide a fertile ground for the growth of eating disorders in other ways, however.

Those with eating disorders often have low self-evaluations, set perfectionist standards, fret about falling short of expectations, and are intensely concerned with how others perceive them (Brauhardt et al., 2014; Pieters et al., 2007; Polivy & Herman, 2002; Sherry & Hall, 2009). Some of these factors also predict teen boys’ pursuit of unrealistic muscularity (Ricciardelli & McCabe, 2004).

Heredity also matters. Identical twins share these disorders more often than fraternal twins do (Culbert et al., 2009; Klump et al., 2009; Root et al., 2010). Scientists are now searching for culprit genes, which may influence the body’s available serotonin and estrogen (Klump & Culbert, 2007). In one analysis of 15 studies, having a gene that reduced available serotonin added 30 percent to a person’s risk of anorexia or bulimia (Calati et al., 2011).

But these disorders also have cultural and gender components. Ideal shapes vary across culture and time. In impoverished areas of the world, including much of Africa—where plumpness means prosperity and thinness can signal poverty or illness—bigger seems better (Knickmeyer, 2001; Swami et al., 2010). Bigger does not seem better in Western cultures, where, according to 222 studies of 141,000 people, the rise in eating disorders in the last half of the twentieth century coincided with a dramatic increase in women having a poor body image (Feingold & Mazzella, 1998).

Those most vulnerable to eating disorders are also those (usually women or gay men) who most idealize thinness and have the greatest body dissatisfaction (Feldman & Meyer, 2010; Kane, 2010; Stice et al., 2010). Should it surprise us, then, that when women view real and doctored images of unnaturally thin models and celebrities, they often feel ashamed, depressed, and dissatisfied with their own bodies—the very attitudes that predispose eating disorders (Grabe et al., 2008; Myers & Crowther, 2009; Tiggeman & Miller, 2010)? Eric Stice and his colleagues (2001) tested this modeling idea by giving some adolescent girls (but not others) a 15-month subscription to an American teen-fashion magazine. Compared with those who had not received the magazine, vulnerable girls—defined as those who were already dissatisfied, idealizing thinness, and lacking social support—exhibited increased body dissatisfaction and eating disorder tendencies. Even ultra-thin models do not reflect the impossible standard of the classic Barbie doll, who had, when adjusted to a height of 5 feet 7 inches, a 32–16–29 figure (in centimeters, 82–41–73) (Norton et al., 1996).

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There is, however, more to body dissatisfaction and anorexia than media effects (Ferguson et al., 2011). Peer influences, such as teasing, also matter. So does affluence, increased marriage age, and especially, competition for available mates.

Nevertheless, the sickness of today’s eating disorders stems in part from today’s weight-obsessed culture—a culture that says, in countless ways, “Fat is bad,” that motivates millions of women to be “always dieting,” and that encourages eating binges by pressuring women to live in a constant state of semistarvation. One former model told the story of how her anorexia caused her organs to fail (Caroll, 2013). Starving from not having eaten for days, she walked into a meeting with her modeling agent, who greeted her by saying, “Whatever you are doing, keep doing it.”

If cultural learning contributes to eating behavior, then might prevention programs increase acceptance of one’s body? Reviews of prevention studies answer Yes. They seem especially effective if the programs are interactive and focused on girls over age 15 (Beintner et al., 2012; Stice et al., 2007; Vocks et al., 2010).

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A growing number of people, especially teenagers and young adults are being diagnosed with psychological disorders. Although mindful of their pain, we can also be encouraged by their successes. Many live satisfying lives. Some pursue brilliant careers, as did 18 U.S. presidents, including the periodically depressed Abraham Lincoln, according to one psychiatric analysis of their biographies (Davidson et al., 2006). The bewilderment, fear, and sorrow caused by psychological disorders are real. But, as this text’s discussion of therapy shows, hope, too, is real.

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