Overweight and obesity are among the most stigmatizing and least socially acceptable conditions in childhood and adolescence. Society, culture, and the media send children powerful messages about body weight and shape ideals. For girls these include the "thin ideal" and encouragement to diet and exercise. Messages to boys emphasize a muscular body and pressure to body build and even use potentially harmful dietary supplements and steroids. While gender has not been identified as a specific risk factor for obesity in children, the pressure placed on girls to be thin may put them at greater risk for developing eating-disordered behaviors. Although society presents boys with a wider range of acceptable body images, they also are at risk for developing disordered eating and body image disturbances. Several studies have reported that at age thirteen, girls' and boys' assessments of their bodies were comparable, but by age fifteen girls' body image had worsened significantly.

Adolescence is a developmental period marked by great physical change, and it is a time when many teens subject themselves to painful scrutiny. Uneven growth, puberty, and sexual maturation may make teens feel awkward and self-conscious about their bodies. Teenage girls are especially susceptible to developing negative body images—ignoring other qualities and focusing exclusively on appearance to measure their self-worth. This single-minded, and often distorted, destructive focus can result in lowered self-esteem and increased risk for mental health problems, including eating disorders.

Although there are biological, genetic, and familial factors that predispose to such eating disorders as anorexia nervosa (intense fear of becoming fat even when dangerously underweight) and bulimia (recurrent episodes of binge eating followed by purging to prevent weight gain) the emergence of these disorders is triggered by environmental factors. Chief among the environmental triggers is body image. Many researchers and health professionals believe that teenage girls who identify with the idealized body images projected throughout American culture are at increased risk for eating disorders.

Other risk factors are peer group pressures and such sociocultural forces as the fashion and entertainment industries and the media. The National Eating Disorders Association identifies media definitions of beauty, attractiveness, and health as among the myriad factors contributing to the rise of eating disorders. A 1997 survey conducted by the Commonwealth Fund, In Their Own Words: Adolescent Girls Discuss Health and Health Care Issues, found that the media were their primary source of information about women's health issues. Another study found that in the course of twenty years three-quarters of articles about fitness or exercise plans in one teen adolescent magazine named "to become more attractive" as the reason to start exercising and 51 percent cited the need to lose weight or burn calories.

Historically, the majority of adolescents with eating disorders have been first- or second-born white females from middle- to upper-class families. Girls who suffer from anorexia are often academically successful, with athletic prowess or training in dance. They tended to be perfectionists, well-behaved, emotionally dependent, socially anxious, and intent on receiving approval from others. Adolescent girls with bulimia were generally more extroverted and socially involved. In the early twenty-first century the occurrence of eating disorders is increasing among younger children and throughout diverse ethnic and sociocultural groups. As many as 1 percent of adolescents have anorexia nervosa and between 2 and 3 percent suffer from bulimia.

According to the National Eating Disorders Association, surveys have found that preoccupation with thinness and dieting begins at an early age. One study reported that 42 percent of first- to third-grade girls said they wanted to be thinner, and another found that 81 percent of ten-year-olds feared becoming fat. Between 30 and 40 percent of middle school girls are worried about their weight, and 40 to 60 percent of high school girls diet. A survey of female college students found that 91 percent had attempted to control their weight by dieting, and 22 percent said they were "often" or "always" dieting.

Dianne Neumark-Sztainer and Peter J. Hannan, researchers at the Division of Epidemiology, School of Public Health and the Department of Pediatrics and Adolescent Health, School of Medicine, University of Minnesota, Minneapolis, analyzed a representative sample of 6,728 adolescents in grades 5 to 12 who completed the Commonwealth Fund surveys about the health of adolescent girls and boys. The objectives and results of the research were detailed in "Weight-Related Behaviors among Adolescent Girls and Boys: Results from a National Survey" (Archives of Pediatrics & Adolescent Medicine, vol. 115, no. 6, June 2000). The research aimed to assess the prevalence of dieting and disordered eating among adolescents; the sociodemographic, psychosocial, and behavioral variables that were associated with dieting and disordered eating; and whether adolescents report having discussed weight-related issues with their healthcare providers. (The researchers defined disordered eating as weight-related behaviors such as anorexia and bulimia nervosa, self-induced vomiting, binge eating, inappropriate or extreme dieting, and obesity.)

Subjects were assessed by calculating BMI and eliciting weight-related attitudes and behaviors. For example, dieting was assessed by asking such questions as "Have you ever been on a diet?" and "Why were you dieting?" Behaviors were assessed by posing a question such as "Have you ever binged and purged (which is when you eat a lot of food and then make yourself throw up, vomit, or take something that makes you have diarrhea) or not?" Subjects also were asked "Right now, how would you describe yourself?" to gain an understanding of their perceptions of their weight. Psychosocial and behavioral variables including self-esteem, stress, depression, substance use (of tobacco, alcohol, or illegal drugs), and level of physical activity were also measured and scored using standardized questionnaires and inventories.

The study revealed that 24 percent of the population was overweight, with nearly half of the girls and 20 percent of the boys reporting a history of dieting. Twenty percent of the population reported disordered eating (13 percent of girls and 7 percent of boys), which was associated with a range of behavioral variables including overweight, low self-esteem, depression, suicidal ideation (thoughts, intent, or plans to take one's own life), and substance use. Nearly half of the adolescents recalled discussions about nutrition with a health-care provider, but just 24 percent of girls and 15 percent of boys said they had discussed eating disorders with a health-care provider.

Younger girls (grades 5–8) were significantly less likely to engage in dieting and disordered eating than older girls (grades 9–12), and dieting was reported by 31.1 percent of the fifth-grade girls and increased to 62.1 percent among twelfth-grade girls. The prevalence of disordered eating was highest among Hispanic girls and lowest among black non-Hispanic girls, and the prevalence of dieting was highest among white non-Hispanic girls and lowest among black non-Hispanic girls. The researchers observed that the prevalence rates of dieting behaviors were lowest among black girls, suggesting that black girls may experience lower levels of body dissatisfaction than white girls.

Alcohol and drug use were directly associated with dieting and disordered eating among girls and boys; however, the association between substance use and disordered eating was stronger than the association between substance use and dieting. Tobacco use was associated with dieting and disordered eating among girls, but not among boys.

The researchers were heartened to discover that "about half of the youth reported that a health-care provider had discussed nutrition and weight issues with them," and observed that while the content of such discussions was unclear, "at least the youth remembered that the issues had been discussed." They concluded that "the high rates of dieting and disordered eating behaviors, coupled with the high prevalence of obesity found in this and previous studies indicate a clear need for interventions aimed at the primary and secondary prevention of weight-related disorders. The large scope of the problem and the complexity of the issues at hand indicate that there is a need for multiple interventions at the individual and familial level (e.g., within clinical practices), at the group level (e.g., within school settings), and at the community or larger societal level (e.g., changes in the physical and social environment)."