and eating are influenced by developmental, social, and cultural factors, or a healthy weight regulation (HWR) model. Other studies focus on broader issues such as increasing self-esteem, empowerment, confidence, and general skills, or a self-esteem/social competence (SESC) model. Many studies focus on reducing the onset of eating disorder symptoms, particularly bulimic pathology. Little is known about prevention of the onset of anorexia nervosa, but given the low prevalence of this disorder, it would be difficult for prevention studies to recruit sufficient sample sizes to detect significant effects.

Eating-disordered attitudes and behaviors are difficult to alter because they are strongly reinforced by a variety of family, peer, medical, and other cultural factors. Consequently, some prevention researchers have argued for the need to change the environment of children and adolescents, specifically, the school environment (Neumark-Sztainer, 1996; Piran, 1999; see also Levine & Piran, 2001). Piran (1999), an advocate of this approach, has demonstrated that systemwide changes can reduce eating disorders in the high-risk setting of an elite ballet school. Neumark-Sztainer, Sherwood, Coller, and Hannan (2000) designed a community-based intervention to prevent disordered eating among preadolescent girls, and randomized 226 Girl Scout troop members into control and intervention groups. The intervention consisted of six 90-minute sessions focusing on media literacy and advocacy skills, with some training for troop leaders. At 3-month follow-up, the program demonstrated a positive influence on media-related attitudes and behaviors including internalization of sociocultural ideals, self-efficacy to impact weight-related social norms, and print media habits. Unfortunately, manipulation of system or setting variables to prevent the development of eating disorders has not been well tested in other settings or by other researchers.

A number of studies, usually focused on older adolescents or college students, have shown that interventions targeted at high-risk students can be effective. Because most of these studies included self-selected and older samples, extrapolation of their success to adolescents should be made cautiously. Stice, Trost, and Chase (2003) randomly assigned high school and college students to a dissonance treatment, a healthy weight management condition, or a waiting-list control. With this approach, the participants were asked to help create a program to teach younger girls body acceptance and to avoid internalizing the thin-body ideal. The theory is that participating students will change their own attitudes and beliefs to better conform to the messages they are developing for the younger girls. At 6-month follow-up, the dissonance group had a sustained reduction in internalization of the thin ideal, but the effects for the other measures dissipated after the program (body dissatisfaction) or at 6-month follow-up (negative affect and bulimic behavior). If anything, the healthy weight intervention resulted in longer-term improvements in negative affect and bulimic symptoms.

Results from other studies reporting the effects of both brief and more intense psycho

educational programs have also been mixed. Mann et al. (1997) evaluated the effects of recovered classmates describing their experience with having an eating disorder and providing information about eating disorders to fellow students. At the posttest, intervention participants had slightly more symptoms of eating disorders than did controls. Franko (1998) found little benefit from a more intensive eight-session psychosocial support group, whereas Stice and Ragan (2002) and Springer, Winzelberg, Perkins, and Taylor (1999) found some positive effects of college courses on body image and disordered eating.

In a series of studies using a computer-assisted HWR program, Taylor and colleagues found improvements in body image and eating behaviors of self-selected high-risk college students (Taylor, Winzelberg, & Celio, 2001). Studies of students with borderline symptoms of clinical disorders have also been promising. For instance, Kaminski and McNamara (1996) randomized 315 at-risk female college students to a no-treatment control or a cognitive-behavioral group, and at 1-month follow-up the intervention group demonstrated significant improvements in weight management behavior, body satisfaction, and self-esteem, and less fear of negative evaluation. These and more clinically focused studies show that intensive, targeted interventions can reduce risk factors, at least in the short term.

The prevention of disordered eating is an important issue in public health. Many young girls and women, as well as boys, suffer from severe and potentially chronic problems with body image, eating, and various forms of unhealthy weight management. In addition, efforts to combine prevention efforts for eating disorders and obesity are important, as some of the fundamental factors that influence disordered eating may also contribute to obesity. The data on the prevention of both eating disorders and cigarette smoking and other drug use (Tobler et al., 2000) also suggest that curricula in the schools alone are not sufficient to produce sustained preventive effects.

Universal prevention efforts with elementary school children have produced positive changes in the relevant knowledge and attitudes of students. Programs that focus on changing factors with broad application, such as increasing self-esteem, creating a stronger sense of connection to peers and mentors, and transforming critical awareness into cultural change, have proved promising with middle school students, but it is unclear whether interventions using the HWR

model are of benefit to children in middle school. High school students are a very difficult target audience for universal prevention, as evidenced by nine studies in five different countries producing no significant effects on attitudes and behaviors. Thus it remains unclear whether universal prevention interventions are effective for preventing eating disorders.

A recent meta-analysis of universal prevention studies concluded that the evidence does not “allow any firm conclusions to be made about the impact of prevention programs for eating disorders in children and adolescents” (Pratt and Woolfenden, 2002), and with similar data, others have concluded that universal prevention is ineffective and should be abandoned. However, a dearth of universal prevention studies is different from a proven lack of effectiveness, particularly when well-designed studies of multidimensional interventions are rare. Many questions remain about universal prevention programs, such as how these programs can have stronger and more long-lasting effects on risk factors, what the ideal age is for such interventions, what the advantages and disadvantages are of combined interventions, how to include environmental and family factors, and whether programs should be provided to both boys and girls in the same setting.

The general lack of effectiveness of programs aimed at preventing eating disorders in adoles cents also needs to be put in the context of substantial research done on prevention of substance abuse, high-risk sexual behavior, and juvenile delinquency and violence (Nation et al., 2003). In an extensive review, the authors concluded that effective prevention programs need to be comprehensive, include varied teaching methods, provide sufficient dosage, be theory driven, provide opportunities for positive relationships, be developmentally appropriate and socioculturally relevant, include outcome evaluation, and involve well-trained staff. Few of the eating disorder prevention studies meet all these characteristics.

A number of studies have demonstrated that interventions targeting high-risk students can be effective, but because many of these studies focused on self-selected and older samples, caution is needed in generalizing the findings to adolescents. Analyses of universal prevention studies suggest that the HWR model might work for high-risk students, but surprisingly little research has focused on students in high-risk settings. Although targeted interventions have proven effective, their effects are generally short-lived and specific to a few dimensions. The challenges in delivering targeted interventions, particularly to populations, are substantial. For example, in school settings, the identification and motivation for high-risk individuals to participate in interventions may be difficult.