Disordered eating attitudes and behaviours in teenaged girls: a school-based study

The female adolescent years are often associated with weight and shape concerns and with disordered eating behaviour in Western countries, in which a thin body is considered desirable.1^,2 Many young women in Canada report feeling dissatisfied with their weight and want to lose weight. In one study, it was found that, by the age of 18 years, 80% of girls of normal height and weight reported that they would like to weigh less.3 Although most of these attitudes and weight loss behaviours are often benign, their presence can still carry significant psychological and medical risks3^,4^,5^,6^,7 and are associated with an increased subsequent risk of clinical eating disorders.8^,9 Furthermore, disordered eating behaviours are associated with an increased risk of other health-compromising behaviours, such as smoking, alcohol and drug use, depression and suicide.3^,6^,10^,11^,12

The evaluation of disordered eating attitudes and behaviours in nonclinical samples is necessary to monitor and track trends and changes in prevalence and to assist in the development and planning of preventive and treatment programs. Recent evidence from the United States and Europe suggests that disordered eating behaviours may be increasing in prevalence,10^,13^,14 and it has been suggested that the age of onset of these disorders may be decreasing.10^,15^,16^,17 However, prevalence figures from such research have varied widely depending on the methodology employed and the sample studied. In addition, most studies have considered older adolescents and young adults rather than the full adolescent age spectrum.

The present cross-sectional study was designed to assess the prevalence of disordered eating attitudes and behaviours in a large school-based population in Ontario.

Methods

We invited 2483 female students, aged 12–18 years, from junior high and high schools in Toronto, Ottawa and Hamilton to participate in a confidential, cross-sectional self-report study of eating attitudes and behaviour. Individual schools were identified, based on their location and number of students, and the principals of the schools were approached by the school board's research coordinator. Schools in which studies were already taking place or who reported that they were short staffed were not approached. In total, 5 schools in Ottawa (including one rural, one suburban, 2 central and one private school), 4 schools in Hamilton (distributed across the city) and 9 schools in the Greater Toronto Area (1 rural, 4 suburban and 4 central) participated in the study. Principals or administrative staff at each school provided a list of classes. Girls were introduced to the study either during homeroom class (the boys were excused) or at a general assembly, for which they were excused from class. In some cases, girls were recruited from specific classes. In order to prevent any sampling bias, we only included classes that were mandatory for all girls. Consent and demographic forms were distributed to be signed and completed by the students and by their parents, if the students were less than 18 years of age (as required by the school boards). All participants completed a self-report screening package, which included the 3 core subscales of the Eating Disorder Inventory (EDI),18 the Eating Attitudes Test-26 (EAT-26)19 and the Diagnostic Survey for Eating Disorders (DSED).20 Before they filled out the survey, all participants were provided with a clear definition of dieting and binge eating and a description of what was meant by self-induced vomiting and diuretic and diet pill use. Body mass index (BMI) was calculated (kg/m²), based on self-reported height and weight, and was entered into the regression models in quartiles, based on the distribution within each age group. Socioeconomic status (SES) was based on Statistics Canada Income Tax and Postal Code data. The study protocol was approved by the scientific review committees at the participating school boards. Participants were informed that the results were confidential.

Results

Of the 2483 eligible girls, 1829 (74%) returned signed consent forms and agreed to take part in the study; 301 refused to participate (12%) and 353 (14%) did not return their consent forms and were considered to be nonparticipants. Ninety girls were absent or could not participate because of school tests on the day we administered the self-report survey. Screening data were collected from 1739 girls (70%) (Toronto n = 655; Ottawa n = 680; Hamilton n = 404).

Characteristics of the sample are presented in Table 1. The mean age of subjects in the sample was 14.6 (standard deviation 1.9) years. As expected, BMI increased with age, and most subjects were postmenarcheal (86%). There were no significant differences among the 3 sites in the demographic characteristics of the subjects or in their responses on the self-report measures.

Disordered eating attitudes

The breakdown of the mean EAT-26 and EDI subscale scores according to age is presented in Table 2. There were significant increases in the Drive for Thinness (p < 0.001), Body Dissatisfaction (p < 0.001), and Bulimia (p = 0.004) subscales with age. EDI subscale and EAT-26 total scores were significantly higher in the teens aged 15-18 years compared with those aged 12–14 years (p < 0.001). Fourteen percent of the total sample, 13% of those under age of 15 years and 16% of those aged 15–18 years (p = 0.05) had scores above the recommended cut-off of 20 on the EAT-26 (Fig. 1).

View this table:

• View inline
• View popup
• Download powerpoint

Table 2.

• Download figure
• Open in new tab
• Download powerpoint

Fig. 1: Percentage of participants with an EAT-26 score above the recommended cut-off of 20. 19

Subjects who completed the DSED were asked to rate how they felt about their weight on a 5-point scale. In total, 38% of the respondents reported feeling a bit or very overweight, including 33% of girls under 15 years of age and 44% of the older girls (p = 0.01). Forty-seven percent of the girls reported feeling a bit or very unhappy about their weight, including 43% of girls under 15 years and 52% of girls aged 15 years and over (p = 0.01).

Interpretation

Our data indicate that an alarming number of Ontario schoolgirls report disordered attitudes about food and weight and unhealthy weight loss behaviour. Significant symptoms of eating disorders, reflected in EAT-26 scores of above 20 and bingeing or purging, or both, were reported by 27% of girls aged 12–18 years. Whereas dieting was the most prevalent weight loss behaviour, other unhealthy weight loss behaviours such as self-induced vomiting were also common. In addition, dieting, binge eating and purging overlapped significantly.

In the present study, disordered eating attitudes (as measured by the EDI and EAT-26) and behaviours such as dieting, bingeing and purging were found to increase gradually throughout adolescence, which is a finding consistent with other studies.23 However, the number of girls who were already engaging in severely disordered behaviours at the ages of 12, 13 and 14 years was striking. Twelve percent of girls aged 12–14 years reported binge-eating episodes in the previous month, and almost 7% of this age group reported self-inducing vomiting to lose weight. By the age of 15 years, disordered eating attitudes and behaviours were as frequent as those reported in older high-risk groups, such as college and university students.24

The present study indicates that most teenaged girls with disordered eating behaviours, even those who are inducing vomiting or taking diet pills, are not evaluated or treated for these problems. Current treatment programs for established eating disorders are not a realistic or adequate response to this widespread public health problem, in view of the limited resources available to treat “full- syndrome” eating disorders and the tendency for such disorders to become chronic and resistant to treatment.25

Over the past several decades, researchers and clinicians have argued for the need to shift away from the traditional medical treatment model to a public health model that focuses on primary and secondary prevention and the development and implementation of appropriate public policies.26 However, until recently, very little empirical research on prevention has been reported, and many of the programs have typically consisted of curriculum-based didactic sessions focused on giving girls information about eating disorders, warning about the dangers of unhealthy weight loss behaviours and encouraging healthy eating and exercise. Although providing information does appear to increase knowledge, these programs do not engage participants emotionally and appear to do little to change or prevent unhealthy attitudes and behaviours.27^,28^,29 New interactive and student-centred approaches, which focus on self-esteem and are based on contemporary theories of female development, appear to be promising. These interventions focus on the positive aspects of the self and validate girls' experiences and feelings, while providing them with an understanding of the societal pressures that they face.30^,31

Although there is no clearly established effective method of prevention, it is essential that we increase awareness in professionals so that every opportunity is taken to screen or intervene, or both, and to promote positive feelings about the body. Family practitioners and pediatricians can play an important role in the prevention and detection of unhealthy eating attitudes and behaviours and associated complications.10^,32 Nonjudgemental questions regarding body image and eating attitudes and behaviour can allow these problems to be detected in the primary care setting. Unfortunately, most physicians do not regularly screen for eating disorders,33 although the present study suggests that disordered eating attitudes and behaviours are sufficiently common, at least in Canadian adolescent females, to warrant such routine inquiry.

In the present study, SES was not significantly associated with disturbed eating attitudes or behaviour. This finding, which is consistent with reports from the past 2 decades,34^,35 probably reflects the pervasive influence of the media on all SES groups. Age and BMI were independently associated with disturbed eating attitudes and behaviours, as has been found in previous studies.35^,36 This association between BMI and eating disturbances suggests a potential link between disordered eating and overweight. In a recent Canadian study, the prevalence of obesity in children was shown to have doubled over the past 20 years.37 This growing disparity between what is considered to be the “ideal” body shape and the reality of the body shape of most girls may be responsible for the increased prevalence of dieting in Western cultures. Although weight loss strategies may seem desirable for overweight females, they are often ineffective and may actually result in weight gain and eating disturbances. Indeed, dietary restraint, exercise, diet pills and the use of laxatives to achieve weight loss are all associated with an increased risk of obesity.38 Binge eating has also been shown to result in weight gain and increased risk of obesity,39 suggesting that disordered eating and increased BMI may be mutually exacerbating.

Limitations of the present study include its cross- sectional design that cannot assess the progression of symptoms over time and the absence of structured diagnostic interviews to diagnose eating disorders. Self-report measures, which have been used in the present study, may lead to underreporting or to underestimation of symptoms of eating disorders. BMI was assessed using self-report data, which, it has been suggested, may result in an underestimation of BMI in adolescent females. Although this self-report bias may have underestimated BMI in the present study, we expect that the magnitude of overreporting or underreporting of height or weight, or both, would probably be small. SES was derived from Statistics Canada postal walk income data that are considered to be a fairly good estimate of SES, however, they are based on averages within neighborhoods and are not specific to each household. Finally, although the response rate of 70% in the present study is relatively high, the possibility of volunteer bias cannot be excluded.

The present study indicates that disordered eating attitudes and behaviours are present in more than one-quarter of Ontario schoolgirls, particularly those with higher BMI values. Although these attitudes and behaviours were more common in older teenaged girls, they were also reported by 20% of those aged 12–14 years. The latter represent a group, in addition to those with high BMI values, who may benefit from primary prevention and early intervention measures. The data from this study suggest that girls should be screened for eating disturbances before they enter middle school and targeted for primary and secondary preventive interventions.