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Eating disorder behaviors and attitudes in Japanese adolescent girls and boys in high schools
Psychiatry Research 230 (2015) 722–724
Contents lists available at ScienceDirect
Psychiatry Research journal homepage: www.elsevier.com/locate/psychres
Short communication
Eating disorder behaviors and attitudes in Japanese adolescent girls and boys in high schools Yoshikatsu Nakai a,n,1, Shun’ichi Noma b,1, Kazuko Nin c,1, Satoshi Teramukai d,1, Stephen A. Wonderlich e,1 a
Kyoto Institute of Health Sciences, Miyako Bldg. 502, Nijyo Den-cho, Nakagyo-ku, Kyoto, Japan Department of Psychiatry, School of Medicine, Kyoto University, Kyoto, Japan c School of Health Sciences, Faculty of Medicine, Kyoto University, Kyoto, Japan d Department of Biostatistics, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan e Department of Psychiatry and Behavioral Science, School of Medicine and Health Sciences, University of North Dakota, Fargo, ND, USA b
art ic l e i nf o
a b s t r a c t
Article history: Received 22 April 2015 Received in revised form 29 July 2015 Accepted 28 September 2015 Available online 30 September 2015
To investigate eating disorder behaviors and attitudes in adolescents, we administered the eating disorder examination questionnaire (EDE-Q) to Japanese adolescent girls and boys. The EDE-Q global scores in Japanese girls and boys, respectively, were significantly lower than those in girls and boys in previous studies. Objective binge eating episodes and extreme dietary restriction were the common behaviors, whereas self-induced vomiting and the misuse of laxatives were uncommon. Differences in the EDE-Q data between Japanese adolescents and adolescents in previous studies from Western countries suggest that there may be certain cultural differences in eating disorder psychopathology in adolescents. & 2015 Elsevier Ireland Ltd. All rights reserved.
Keywords: Eating disorder examination questionnaire Eating disorder psychopathology Cross-cultural
1. Introduction The number of patients with eating disorders in Japan has increased by tenfold in community samples as well as in clinical samples from 1980 to the present (Nakai et al., 2014b). In addition to the prevalence of eating disorders, examination of the prevalence of eating disorder symptoms is important because data on symptom prevalence provide an indication of the size of the atrisk group. To clarify the transcultural differences in eating disorder symptom dimensions, standardized measures of disordered eating behaviors and attitudes are useful. The Eating Disorder Examination Questionnaire (EDE-Q) (Fairburn and Beglin, 1994) is a self-reported measure of eating disorder behaviors and attitudes. It is used extensively for both clinical and research purposes and normative data are available for various study populations, including adolescents, college students and young adults (Berg et al., 2012). When we administered the EDE-Q to undergraduate Japanese women (Nakai et al., 2014a), n Correspondence to: Kyoto Institute of Health Sciences, Miyako Bldg. 502, Karasuma Oike Agaru Higashigawa, Nakagyo-ku, Kyoto 604-0845, Japan. Fax: þ81 75 241 4602. E-mail address: [email protected] (Y. Nakai). 1 Members of Kyoto Prefectural Association of School Nurses of High Schools in Block B in Kyoto City.
http://dx.doi.org/10.1016/j.psychres.2015.09.045 0165-1781/& 2015 Elsevier Ireland Ltd. All rights reserved.
there were significant differences in normative data for the EDE-Q between them and women in Western countries, suggesting that there may be certain cultural differences in terms of eating disorder psychopathology in undergraduate women. Epidemiological data suggest that not only college but also high school can be a time of heightened risk for the development of eating disorder symptoms and eating disorders in Japan (Nakai et al., 2014b). Hence, to investigate eating disorder behaviors and attitudes in Japanese adolescents, we administered the EDE-Q to Japanese adolescents and compared the EDE-Q data to adolescent norms for the EDE-Q obtained from previous studies.
2. Methods 2.1. Study design and participants Participants were recruited from among female and male high school students (n ¼4080) attending 6 out of 7 schools in Block B of Kyoto Prefectural School Nurses Association of High Schools in Kyoto City, an urbanized region of Kyoto Prefecture in Japan. The responsible individuals in the schools randomly selected which classes would participate. All students (n ¼1227) in the classes selected for participation were approached to participate in a study of eating attitudes and behaviors involving completion of a
Y. Nakai et al. / Psychiatry Research 230 (2015) 722–724
brief questionnaire, in their classrooms, during school hours on an anonymous and voluntary basis in July 2014. Answer sheets were collected in a collection box. There was no incentive or payment for completing the questionnaire. Both students and their parents were informed of the study aims and method and their right to decline to participate. The study design and methods were approved by the Ethics Committee of Kyoto University Graduate School and Faculty of Medicine. The completed questionnaire was received from 1124 students, a participation rate of 91.6%. Data for 65 participants who did not indicate their gender or were found to have missing data were excluded. The final sample therefore comprised 1059 students, aged 15–18 years. Of these, 536 (50.6%) were female and 523 were male students. All participants were of Japanese ethnicity. 2.2. Study measures The questionnaire was comprised of an assessment of demographic information (gender, age, height, weight and menstruation) and the EDE-Q. The EDE-Q (version 6.0) (Fairburn and Beglin, 2008) is a 28-item, self-reported measure that assesses attitudes, feelings and behaviors related to eating and body image over the past 28 days. It yields a global score and four subscale scores: restraint, eating concern, shape concern and weight concern. It also assesses individuals' engagement in objective binge eating episodes (OBEs), as well as a range of compensatory behaviors within the previous 28 days. On the basis of previous studies (Nakai et al., 2014a), regular engagement in OBEs, self-induced vomiting and misuse of laxatives and/or diuretics were defined as those occurring at least weekly, whereas regular excessive exercise and extreme dietary restriction were recognized if these behaviors occurred, on average, three or more times per week. The Japanese translation of the EDE-Q was performed by the first author and controlled by a retranslation through a professional translator, using the techniques of back-translation, discussion and pilot studies, as previously described (Nakai et al., 2014a). 2.3. Statistical analysis All of the analyses were conducted with SPSS 13.0. Reliability coefficients (Cronbach's alpha) for the EDE-Q global and four subscale scores were calculated. Two-sample t-test was used to compare two groups. Differences in the proportion variables were evaluated using chi-square tests.
3. Results Cronbach's alphas for the EDE-Q in the present study ranged from 0.638 (eating concern) to 0.910 (shape concern) for girls and from 0.687 (eating concern) to 0.839 (shape concern) for boys. Table 1 presents the results of comparison of the EDE-Q global and four subscale scores between high school girls and boys. Mean scores for the EDE-Q global and four subscale scores were all significantly higher among girls than among boys. Table 1 also presents the percentages of girls and boys who reported any occurrence and regular occurrence of key eating disorder behavioral features and compensatory behaviors. As can be seen, OBEs and extreme dietary restriction were the common behaviors in both girls and boys in this sample, whereas self-induced vomiting and the misuse of laxatives and/or diuretics were uncommon. Significantly greater percentages of girls than boys reported OBEs, extreme dietary restriction and regular occurrence of extreme dietary restriction.
723
Table 1 Comparison of level and occurrence of eating attitudes and behaviors of the EDE-Q between girls and boys.
Age (years) BMI (kg/m2) EDE-Q global Restraint Eating concern Shape concern Weight concern Objective binge eating Self-induced vomiting Laxative misuse Diuretic misuse Excessive exercise Extreme dietary restriction
Any Regular Any Regular Any Regular Any Regular Any Regular Any Regular
Girls (n¼536) Mean (SD)
Boys (n¼523) Mean (SD)
Statistics t
p
16.0 (0.7) 20.4 (3.2)a 1.36 (1.10) 0.67 (1.07) 0.47 (0.71) 2.30 (1.66) 1.99 (1.54) Percent 9.0 4.4 1.1 0.2 1.5 0.2 0.2 0 4.2 0.6 15.1 3.2
16.0 (0.7) 20.6 (3.6)b 0.32 (0.54) 0.10 (0.45) 0.13 (0.43) 0.59 (0.92) 0.46 (0.79) Percent 4.7 2.0 0.8 0.2 0.8 0 0.4 0 2.2 0.6 3.8 0.8
0.01 0.93 19.5 11.1 9.3 20.6 20.3 χ2 6.69 2.21 0.07 0.47 0.60 0.01 0.01 0.01 2.83 0.14 37.8 7.89
n.s. n.s. o 0.001 o 0.001 o 0.001 o 0.001 o 0.001 p o 0.01. n.s. n.s. n.s. n.s. n.s. n.s. n.s. n.s. n.s. o 0.001 o 0.01
n.s.: Not significant. a b
497 Female participants. 509 Male participants.
4. Discussion We reported EDE-Q for adolescent girls and boys recruited from high schools in an urbanized region of Kyoto Prefecture in Japan. As expected, EDE-Q global and four subscale scores were all higher among girls than among boys. In addition, the prevalence of OBEs and extreme restriction in girls was significantly higher than in boys. Differences noted between girls and boys in this study highlight gender-based societal influences on body image and eating behaviors in Japan. As previously documented (Nakai et al., 2014b), slimness has been the standard of beauty in Japanese adolescent girls and young women, under the influence of Western culture. Overall, the levels of eating disorder psychopathology, assessed by the EDE-Q, in adolescent girls and boys in this study were lower than those in two other Western studies previously reported (Mond et al., 2014; White et al., 2014). The prevalence rates of OBEs and extreme dietary restriction in Japanese girls and boys, respectively, in the present study were significantly lower than those in girls and boys in previous studies (Mond et al., 2014; White et al., 2014). This finding was unexpected because, in our previous study (Nakai et al., 2014a), Japanese undergraduate women reported significantly more OBEs than undergraduate women in Western countries. The adolescent girls in the present study reported significantly lower prevalence rates of OBEs and extreme dietary restriction than undergraduate women in our previous report. The following question thus arises: Why were the prevalence rates of OBEs and extreme dietary restriction low in Japanese high school adolescents in the current study? A possible explanation for this is that there are excellent health care systems in Japanese high schools. For example, all high school students undergo regular physical examinations. School nurses in each high school are advisers on both physical and mental problems of students and contact parents and doctors according to prevention programs. Unfortunately, colleges do not have such systems in Japan. With respect to compensatory behaviors, the Japanese girls and boys reported significantly lower prevalence rates of self-induced
724
Y. Nakai et al. / Psychiatry Research 230 (2015) 722–724
vomiting than girls and boys in previous studies (Mond et al., 2014; White et al., 2014). This may be due to effective advertising through the mass media and prevention programs in high schools highlighting that compensatory behaviors including vomiting are harmful to health (Nakai et al., 2014b). Alternatively, participants in this study may have been unwilling to admit to such behaviors. This is the first known study to report normative EDE-Q data of adolescent girls and boys in non-Western countries. Differences in normative data for the EDE-Q between Japanese adolescents in this study and adolescents in previous studies from Western countries (Mond et al., 2014; White et al., 2014) suggest that there may be certain cultural differences in eating disorder psychopathology in adolescents. A limitation of this study is the use of a relatively small, regional sample. A related limitation is that the sample may be influenced by a bias in the recruitment because it is unclear how the responsible individuals randomly selected which classes would participate. Hence, the findings may not be generalizable to Japanese adolescent girls and boys overall. Future research should examine larger, more diverse samples of Japanese adolescent girls and boys from across the nation in order to achieve better assessment of the validity of the EDE-Q for Japanese adolescents. Overall, these findings will help health care professionals and researchers better interpret EDE-Q scores used for eating disorder prevention and treatment programs.
Competing interests The authors do not have any competing interests to report.
Financial disclosure There are no financial interests to disclose.
Authors' contributions Conception of the study: YN, SN and KN. Data collection, entry and analysis: YN, ST and Members of Kyoto Prefectural Association of School Nurses of High Schools in Block B in Kyoto City. Interpretation of the results and manuscript drafting: YN, ST and SAW. Review of the manuscript: all authors.
References Berg, K.C., Peterson, C.G., Frazier, P., Crow, S.J., 2012. Psychometric evaluation of the eating disorder examination and eating disorder examination-questionnaire: a systematic review of the literature. Int. J. Eat. Disord. 45, 428–438. Fairburn, C.G., Beglin, S.J., 1994. Assessment of eating disorders: interview or selfreport questionnaire? Int. J. Eat.Disord. 16, 363–370. Fairburn, C.G., Beglin, S.J., 2008. Eating disorder examination questionnaire (EDE-Q 6.0). In: Fairburn, C.G. (Ed.), Cognitive behavior therapy and eating disorders. Guilford Press, New York, pp. 309–313. Mond, J., Hall, A., Bentley, C., Harrison, C., Gratwick-Sarll, K., Lewis, V., 2014. Eatingdisordered behavior in adolescent boys: eating disorder examination questionnaire norms. Int. J. Eat. Disord. 47, 335–341. Nakai, Y., Nin, K., Fukushima, M., Nakamura, K., Noma, S., Teramukai, S., Taniguchi, A., Wonderlich, S., 2014a. Eating disorder examination questionnaire (EDE-Q): norms for undergraduate Japanese women. Eur. Eat. Disord. Rev. 22, 439–442. Nakai, Y., Nin, K., Noma, S., 2014b. Epidemiological data on eating disorders in Japan. In: Gramaglia, C. (Ed.), New Developments in Anorexia Nervosa Research. Nova Science Publishers, Inc., New York, pp. 173–187. White, H.J., Haycraft, E., Goodwin, H., Meyer, C., 2014. Eating disorder examination questionnaire: factor structure for adolescent girls and boys. Int. J. Eat. Disord. 47, 99–104.
Contents lists available at ScienceDirect
Psychiatry Research journal homepage: www.elsevier.com/locate/psychres
Short communication
Eating disorder behaviors and attitudes in Japanese adolescent girls and boys in high schools Yoshikatsu Nakai a,n,1, Shun’ichi Noma b,1, Kazuko Nin c,1, Satoshi Teramukai d,1, Stephen A. Wonderlich e,1 a
Kyoto Institute of Health Sciences, Miyako Bldg. 502, Nijyo Den-cho, Nakagyo-ku, Kyoto, Japan Department of Psychiatry, School of Medicine, Kyoto University, Kyoto, Japan c School of Health Sciences, Faculty of Medicine, Kyoto University, Kyoto, Japan d Department of Biostatistics, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan e Department of Psychiatry and Behavioral Science, School of Medicine and Health Sciences, University of North Dakota, Fargo, ND, USA b
art ic l e i nf o
a b s t r a c t
Article history: Received 22 April 2015 Received in revised form 29 July 2015 Accepted 28 September 2015 Available online 30 September 2015
To investigate eating disorder behaviors and attitudes in adolescents, we administered the eating disorder examination questionnaire (EDE-Q) to Japanese adolescent girls and boys. The EDE-Q global scores in Japanese girls and boys, respectively, were significantly lower than those in girls and boys in previous studies. Objective binge eating episodes and extreme dietary restriction were the common behaviors, whereas self-induced vomiting and the misuse of laxatives were uncommon. Differences in the EDE-Q data between Japanese adolescents and adolescents in previous studies from Western countries suggest that there may be certain cultural differences in eating disorder psychopathology in adolescents. & 2015 Elsevier Ireland Ltd. All rights reserved.
Keywords: Eating disorder examination questionnaire Eating disorder psychopathology Cross-cultural
1. Introduction The number of patients with eating disorders in Japan has increased by tenfold in community samples as well as in clinical samples from 1980 to the present (Nakai et al., 2014b). In addition to the prevalence of eating disorders, examination of the prevalence of eating disorder symptoms is important because data on symptom prevalence provide an indication of the size of the atrisk group. To clarify the transcultural differences in eating disorder symptom dimensions, standardized measures of disordered eating behaviors and attitudes are useful. The Eating Disorder Examination Questionnaire (EDE-Q) (Fairburn and Beglin, 1994) is a self-reported measure of eating disorder behaviors and attitudes. It is used extensively for both clinical and research purposes and normative data are available for various study populations, including adolescents, college students and young adults (Berg et al., 2012). When we administered the EDE-Q to undergraduate Japanese women (Nakai et al., 2014a), n Correspondence to: Kyoto Institute of Health Sciences, Miyako Bldg. 502, Karasuma Oike Agaru Higashigawa, Nakagyo-ku, Kyoto 604-0845, Japan. Fax: þ81 75 241 4602. E-mail address: [email protected] (Y. Nakai). 1 Members of Kyoto Prefectural Association of School Nurses of High Schools in Block B in Kyoto City.
http://dx.doi.org/10.1016/j.psychres.2015.09.045 0165-1781/& 2015 Elsevier Ireland Ltd. All rights reserved.
there were significant differences in normative data for the EDE-Q between them and women in Western countries, suggesting that there may be certain cultural differences in terms of eating disorder psychopathology in undergraduate women. Epidemiological data suggest that not only college but also high school can be a time of heightened risk for the development of eating disorder symptoms and eating disorders in Japan (Nakai et al., 2014b). Hence, to investigate eating disorder behaviors and attitudes in Japanese adolescents, we administered the EDE-Q to Japanese adolescents and compared the EDE-Q data to adolescent norms for the EDE-Q obtained from previous studies.
2. Methods 2.1. Study design and participants Participants were recruited from among female and male high school students (n ¼4080) attending 6 out of 7 schools in Block B of Kyoto Prefectural School Nurses Association of High Schools in Kyoto City, an urbanized region of Kyoto Prefecture in Japan. The responsible individuals in the schools randomly selected which classes would participate. All students (n ¼1227) in the classes selected for participation were approached to participate in a study of eating attitudes and behaviors involving completion of a
Y. Nakai et al. / Psychiatry Research 230 (2015) 722–724
brief questionnaire, in their classrooms, during school hours on an anonymous and voluntary basis in July 2014. Answer sheets were collected in a collection box. There was no incentive or payment for completing the questionnaire. Both students and their parents were informed of the study aims and method and their right to decline to participate. The study design and methods were approved by the Ethics Committee of Kyoto University Graduate School and Faculty of Medicine. The completed questionnaire was received from 1124 students, a participation rate of 91.6%. Data for 65 participants who did not indicate their gender or were found to have missing data were excluded. The final sample therefore comprised 1059 students, aged 15–18 years. Of these, 536 (50.6%) were female and 523 were male students. All participants were of Japanese ethnicity. 2.2. Study measures The questionnaire was comprised of an assessment of demographic information (gender, age, height, weight and menstruation) and the EDE-Q. The EDE-Q (version 6.0) (Fairburn and Beglin, 2008) is a 28-item, self-reported measure that assesses attitudes, feelings and behaviors related to eating and body image over the past 28 days. It yields a global score and four subscale scores: restraint, eating concern, shape concern and weight concern. It also assesses individuals' engagement in objective binge eating episodes (OBEs), as well as a range of compensatory behaviors within the previous 28 days. On the basis of previous studies (Nakai et al., 2014a), regular engagement in OBEs, self-induced vomiting and misuse of laxatives and/or diuretics were defined as those occurring at least weekly, whereas regular excessive exercise and extreme dietary restriction were recognized if these behaviors occurred, on average, three or more times per week. The Japanese translation of the EDE-Q was performed by the first author and controlled by a retranslation through a professional translator, using the techniques of back-translation, discussion and pilot studies, as previously described (Nakai et al., 2014a). 2.3. Statistical analysis All of the analyses were conducted with SPSS 13.0. Reliability coefficients (Cronbach's alpha) for the EDE-Q global and four subscale scores were calculated. Two-sample t-test was used to compare two groups. Differences in the proportion variables were evaluated using chi-square tests.
3. Results Cronbach's alphas for the EDE-Q in the present study ranged from 0.638 (eating concern) to 0.910 (shape concern) for girls and from 0.687 (eating concern) to 0.839 (shape concern) for boys. Table 1 presents the results of comparison of the EDE-Q global and four subscale scores between high school girls and boys. Mean scores for the EDE-Q global and four subscale scores were all significantly higher among girls than among boys. Table 1 also presents the percentages of girls and boys who reported any occurrence and regular occurrence of key eating disorder behavioral features and compensatory behaviors. As can be seen, OBEs and extreme dietary restriction were the common behaviors in both girls and boys in this sample, whereas self-induced vomiting and the misuse of laxatives and/or diuretics were uncommon. Significantly greater percentages of girls than boys reported OBEs, extreme dietary restriction and regular occurrence of extreme dietary restriction.
723
Table 1 Comparison of level and occurrence of eating attitudes and behaviors of the EDE-Q between girls and boys.
Age (years) BMI (kg/m2) EDE-Q global Restraint Eating concern Shape concern Weight concern Objective binge eating Self-induced vomiting Laxative misuse Diuretic misuse Excessive exercise Extreme dietary restriction
Any Regular Any Regular Any Regular Any Regular Any Regular Any Regular
Girls (n¼536) Mean (SD)
Boys (n¼523) Mean (SD)
Statistics t
p
16.0 (0.7) 20.4 (3.2)a 1.36 (1.10) 0.67 (1.07) 0.47 (0.71) 2.30 (1.66) 1.99 (1.54) Percent 9.0 4.4 1.1 0.2 1.5 0.2 0.2 0 4.2 0.6 15.1 3.2
16.0 (0.7) 20.6 (3.6)b 0.32 (0.54) 0.10 (0.45) 0.13 (0.43) 0.59 (0.92) 0.46 (0.79) Percent 4.7 2.0 0.8 0.2 0.8 0 0.4 0 2.2 0.6 3.8 0.8
0.01 0.93 19.5 11.1 9.3 20.6 20.3 χ2 6.69 2.21 0.07 0.47 0.60 0.01 0.01 0.01 2.83 0.14 37.8 7.89
n.s. n.s. o 0.001 o 0.001 o 0.001 o 0.001 o 0.001 p o 0.01. n.s. n.s. n.s. n.s. n.s. n.s. n.s. n.s. n.s. o 0.001 o 0.01
n.s.: Not significant. a b
497 Female participants. 509 Male participants.
4. Discussion We reported EDE-Q for adolescent girls and boys recruited from high schools in an urbanized region of Kyoto Prefecture in Japan. As expected, EDE-Q global and four subscale scores were all higher among girls than among boys. In addition, the prevalence of OBEs and extreme restriction in girls was significantly higher than in boys. Differences noted between girls and boys in this study highlight gender-based societal influences on body image and eating behaviors in Japan. As previously documented (Nakai et al., 2014b), slimness has been the standard of beauty in Japanese adolescent girls and young women, under the influence of Western culture. Overall, the levels of eating disorder psychopathology, assessed by the EDE-Q, in adolescent girls and boys in this study were lower than those in two other Western studies previously reported (Mond et al., 2014; White et al., 2014). The prevalence rates of OBEs and extreme dietary restriction in Japanese girls and boys, respectively, in the present study were significantly lower than those in girls and boys in previous studies (Mond et al., 2014; White et al., 2014). This finding was unexpected because, in our previous study (Nakai et al., 2014a), Japanese undergraduate women reported significantly more OBEs than undergraduate women in Western countries. The adolescent girls in the present study reported significantly lower prevalence rates of OBEs and extreme dietary restriction than undergraduate women in our previous report. The following question thus arises: Why were the prevalence rates of OBEs and extreme dietary restriction low in Japanese high school adolescents in the current study? A possible explanation for this is that there are excellent health care systems in Japanese high schools. For example, all high school students undergo regular physical examinations. School nurses in each high school are advisers on both physical and mental problems of students and contact parents and doctors according to prevention programs. Unfortunately, colleges do not have such systems in Japan. With respect to compensatory behaviors, the Japanese girls and boys reported significantly lower prevalence rates of self-induced
724
Y. Nakai et al. / Psychiatry Research 230 (2015) 722–724
vomiting than girls and boys in previous studies (Mond et al., 2014; White et al., 2014). This may be due to effective advertising through the mass media and prevention programs in high schools highlighting that compensatory behaviors including vomiting are harmful to health (Nakai et al., 2014b). Alternatively, participants in this study may have been unwilling to admit to such behaviors. This is the first known study to report normative EDE-Q data of adolescent girls and boys in non-Western countries. Differences in normative data for the EDE-Q between Japanese adolescents in this study and adolescents in previous studies from Western countries (Mond et al., 2014; White et al., 2014) suggest that there may be certain cultural differences in eating disorder psychopathology in adolescents. A limitation of this study is the use of a relatively small, regional sample. A related limitation is that the sample may be influenced by a bias in the recruitment because it is unclear how the responsible individuals randomly selected which classes would participate. Hence, the findings may not be generalizable to Japanese adolescent girls and boys overall. Future research should examine larger, more diverse samples of Japanese adolescent girls and boys from across the nation in order to achieve better assessment of the validity of the EDE-Q for Japanese adolescents. Overall, these findings will help health care professionals and researchers better interpret EDE-Q scores used for eating disorder prevention and treatment programs.
Competing interests The authors do not have any competing interests to report.
Financial disclosure There are no financial interests to disclose.
Authors' contributions Conception of the study: YN, SN and KN. Data collection, entry and analysis: YN, ST and Members of Kyoto Prefectural Association of School Nurses of High Schools in Block B in Kyoto City. Interpretation of the results and manuscript drafting: YN, ST and SAW. Review of the manuscript: all authors.
References Berg, K.C., Peterson, C.G., Frazier, P., Crow, S.J., 2012. Psychometric evaluation of the eating disorder examination and eating disorder examination-questionnaire: a systematic review of the literature. Int. J. Eat. Disord. 45, 428–438. Fairburn, C.G., Beglin, S.J., 1994. Assessment of eating disorders: interview or selfreport questionnaire? Int. J. Eat.Disord. 16, 363–370. Fairburn, C.G., Beglin, S.J., 2008. Eating disorder examination questionnaire (EDE-Q 6.0). In: Fairburn, C.G. (Ed.), Cognitive behavior therapy and eating disorders. Guilford Press, New York, pp. 309–313. Mond, J., Hall, A., Bentley, C., Harrison, C., Gratwick-Sarll, K., Lewis, V., 2014. Eatingdisordered behavior in adolescent boys: eating disorder examination questionnaire norms. Int. J. Eat. Disord. 47, 335–341. Nakai, Y., Nin, K., Fukushima, M., Nakamura, K., Noma, S., Teramukai, S., Taniguchi, A., Wonderlich, S., 2014a. Eating disorder examination questionnaire (EDE-Q): norms for undergraduate Japanese women. Eur. Eat. Disord. Rev. 22, 439–442. Nakai, Y., Nin, K., Noma, S., 2014b. Epidemiological data on eating disorders in Japan. In: Gramaglia, C. (Ed.), New Developments in Anorexia Nervosa Research. Nova Science Publishers, Inc., New York, pp. 173–187. White, H.J., Haycraft, E., Goodwin, H., Meyer, C., 2014. Eating disorder examination questionnaire: factor structure for adolescent girls and boys. Int. J. Eat. Disord. 47, 99–104.