Factors of Overweight/Obesity in Taiwanese Adolescents by Shu-Min Chan A Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy Approved September 2012 by the Graduate Supervisory Committee: Bernadette Mazurek Melnyk, Co-Chair Michael Belyea, Co-Chair Angela Chia-Chen Chen Joan E. Dodgson ARIZONA STATE UNIVERSITY December 2012 ABSTRACT Two studies were conducted to test a model to predict healthy lifestyle behaviors, physical activity, and body mass index (BMI) in Taiwanese adolescents by assessing their physical activity and nutrition knowledge, healthy lifestyle beliefs, and perceived difficulty in performing healthy lifestyle behaviors. The study drew upon cognitive behavioral theory to develop this study. The pilot study aimed to test and evaluate psychometric properties of eight Chinese-version scales. The total sample for the pilot study included 186 participants from two middle schools in Taiwan. The mean age was 13.19 for boys and 13.79 for girls. Most scales including Beck Youth Inventory self- concept, Beck Youth Inventory depression, Beck Youth Inventory anxiety, healthy lifestyle beliefs, perceived difficulty, and healthy lifestyle behaviors scales Cronbach alpha were above .90. The Cronbach alpha for the nutrition knowledge and the activity knowledge scale were .86 and .70, respectively. For the primary study, descriptive statistics were used to describe sample characteristics, and path analysis was used to test a model predicting BMI in Taiwanese adolescents. The total sample included 453 participants from two middle schools in Taiwan. The mean age of sample was 13.42 years; 47.5% (n = 215) were males. The mean BMI was 21.83 for boys and 19.84 for girls. The BMI for both boys and girls was within normal range. For path analysis, the chi-square was 426.82 (df = 22, p < .01). The CFI of .62 and the RMSEA of .20 suggested that the model had less than an adequate fit (Hu & Bentler, 1999). For alternative model, dropping the variable of gender from the model, the results indicated that i it in fact was an adequate fit to the data (chi-square (23, 453) =33.75, p> .05; CFI= .98; RMSEA= .03). As expected, the results suggested that adolescents who reported higher healthy lifestyle beliefs had more healthy lifestyle behaviors. Furthermore, adolescents who perceived more difficulty in performing healthy lifestyle behaviors engaged in fewer healthy lifestyle behaviors and less physical activity. The findings suggested that adolescents' higher healthy lifestyle beliefs were positively associated with their healthy lifestyle behaviors. ii TABLE OF CONTENTS LIST OF TABLES…………………………………………………………….viii LIST OF FIGURES……………………………………………………………xi CHAPTER Page 1 INTRODUCTION………………………………………… 1 State of Science of Adolescent Obesity Research……. 1 Statement of the problem……………………………. 4 Purpose of the Study………………………………….. 5 2 LITERATURE REVIEW…………………………………. 7 Adolescence…………………………………………... 7 Culture and Adolescence……………………………... 8 Obesity in Adolescents……………………………… 10 Definition of Obesity…………………………………. 10 Prevalence of Overweight Adolescence……………… 11 Determinant of Obesity in Adolescents………………. 12 Physical activity………………………………………. 12 Dietary Behaviors…………………………………….. 13 Knowledge……………………………………………. 13 Gender………………………………………………... 14 Outcomes of Adolescent Obesity…………………….. 14 Depression, Anxiety and Self-esteem………………… 14 Definition and Related-Concept of Depression………. 16 iii CHAPTER Page Attributes of Depression……………………………… 17 Hopelessness versus Depression Attributes………….. 18 Culture and Mental Health…………………………… 18 Theoretical Framework………………………………. 19 Behavioral Theory……………………………………. 20 Cognitive Theory…………………………………….. 20 Cognitive behavioral theory………………………….. 23 Specific Aims and Hypothesis……………………….. 26 3 METHODOLOGY………………………………………... 30 Design of the Study…………………………………... 30 Sampling for Pilot and Primary Study……………….. 31 Setting and Sample…………………………………… 31 Inclusion/Exclusion criteria…………………………... 32 Instruments…………………………………………… 32 Operational Definitions………………………………. 32 Translation and Back-Translation Procedures……….. 33 Demographic Information……………………………. 34 Body Mass Index…………………………………….. 35 Physical Activity……………………………………... 35 Psychometric Properties of the Instruments…………......... 35 The Beck Youth Inventory……………………… 38 iv CHAPTER Page Self-Concept Scale……………………………… 38 Depression Scale………………………………… 38 Anxiety Scale……………………………………. 39 Healthy Lifestyle Beliefs Scale…………………. 39 Perceived Difficulty Scale………………………. 39 Healthy Lifestyle Behaviors Scale………………. 40 Nutrition Knowledge Scale……………………… 40 Activity Knowledge Scale………………………. 41 Results of EFA and CFA of the instruments for Pilot Study 41 The Beck Youth Inventory……………………… 41 Self-Concept Scale……………………………… 41 Depression Scale………………………………… 47 Anxiety Scale……………………………………. 52 Healthy Lifestyle Beliefs Scale………………….. 58 Perceived Difficulty Scale………………………. 63 Healthy Lifestyle Behaviors Scale………………. 67 Nutrition Knowledge Scale……………………… 72 Activity Knowledge Scale………………………. 78 Human Subject Protocols for Pilot and Primary Study 84 Data Analytic Approach for Primary Study…………. 85 Evaluating Model Fit in Path Model…………………. 86 v CHAPTER Page Missing Data………………………………………….. 88 Limitation of Study…………………………………... 88 4 RESULTS OF PRIMARY STUDY 89 Sample……………………………………………….. 89 Results of Measurement Model for Primary Study…... 91 The Beck Youth Inventory……………………… 91 Self-Concept Scale……………………………… 91 Depression Scale………………………………… 95 Anxiety Scale…………………………………… 99 Healthy Lifestyle Beliefs Scale…………………. 103 Perceived Difficulty Scale………………………. 107 Healthy Lifestyle Behaviors Scale………………. 110 Nutrition Knowledge Scale……………………… 114 Activity Knowledge Scale………………………. 118 Theoretical Path Model………………………………. 122 Alternative Path Model………………………………. 128 Multi-Group Path Model across Gender……………... 130 5 DISCUSSION…………………………………………….. 133 Cultural Perspectives: U.S. vs. Taiwan………………. 139 Limitations & Strengths……………………………… 141 Implications and Future Research Directions………... 142 vi CHAPTER Page Conclusion……………………………………………. 143 REFERENCES……………………………………………. 145 APPENDIX 164 A TABLE OF CONCEPTS ANALYSIS AND PREDICTIVE STUDIES ON ADOLESCENTS……….. 164 B ENGLISH VERSION MEASURES………………….. 172 C CHINESE VERSION MEASURES………………….. 182 D APPROVALLETTER FROM THE INSTITUTIONAL REVIEW BOARD…………………. 191 vii LIST OF TABLES Table Page 1 Mean, Standard Deviation, Skewness, Kurtosis, and Correlation for Self-Concept Scale………………………………………….. 44 2 EFA of Factor loadings for Self-Concept Scale……………….... 45 3 Mean, Standard Deviation, Skewness, Kurtosis, and Correlation for Depression Scale…………………………………………….. 49 4 EFA of Factor loadings for Depression Scale…………………... 50 5 Mean, Standard Deviation, Skewness, Kurtosis, and Correlation for Anxiety Scale………………………………………………... 54 6 EFA of Factor loadings for Anxiety Scale……………………… 56 7 Mean, Standard Deviation, Skewness, Kurtosis, and Correlation for Health Lifestyle Beliefs Scale………………………………. 59 8 EFA of Factor loadings for Health Lifestyle Beliefs Scale……. 61 9 Mean, Standard Deviation, Skewness, Kurtosis, and Correlation for Perceived Difficulty Scale…………………………………... 64 10 EFA of Factor loadings for Perceived Difficulty Scale………… 65 11 Mean, Standard Deviation, Skewness, Kurtosis, and Correlation for Healthy Lifestyle Behaviors Scale………………………….. 68 12 EFA of Factor loadings for Healthy Lifestyle Behaviors Scale… 70 13 Mean, Standard Deviation, Skewness, Kurtosis, and Correlation for Nutrition Knowledge Scale…………………………………. 74 viii Table Page 14 EFA of Factor loadings for Nutrition Knowledge Scale………... 76 15 Mean, Standard Deviation, Skewness, Kurtosis, and Correlation for Activity Knowledge Scale…………………………………... 79 16 EFA of Factor loadings for Activity Knowledge Scale………… 81 17 Psychometric Property of Scales………………………………... 83 18 Descriptive Statistics for Sample Demographics and Variables... 89 19 Mean, Standard Deviation, Skewness, Kurtosis, and Correlation for Self-Concept Scale………………………………………….. 92 20 Mean, Standard Deviation, Skewness, Kurtosis, and Correlation 96 for Depression Scale……………………………………………. 21 Mean, Standard Deviation, Skewness, Kurtosis, and Correlation 100 for Anxiety Scale……………………………………………….. 22 Mean, Standard Deviation, Skewness, Kurtosis, and Correlation for Health Lifestyle Beliefs Scale………………………………. 104 23 Mean, Standard Deviation, Skewness, Kurtosis, and Correlation for Perceived Difficulty Scale…………………………………... 108 24 Mean, Standard Deviation, Skewness, Kurtosis, and Correlation for Healthy Lifestyle Behaviors Scale………………………….. 111 25 Mean, Standard Deviation, Skewness, Kurtosis, and Correlation for Nutrition Knowledge Scale…………………………………. 115 26 Mean, Standard Deviation, Skewness, Kurtosis, and Correlation for Activity Knowledge Scale…………………………………... 119 ix Table Page 27 Correlation Matrix between Variables in the Conceptual Path Model…………………………………………………………… 122 28 Bootstrap Analysis of Magnitude and Statistical of Indirect Effects........................................................................................... 127 29 Model Fit Statistics for Systematically Multi-group Analysis across Gender…………………………………………………… 131 x LIST OF FIGURES Figure Page 1 Cognitive-Behavioral Theory Conceptual Model (CBT model) to predict BMI…………………………………………………………… 26 2 Presentation of conceptual path model of relations among variables to predict BMI………………………………………… 31 3 CFA of Factor loadings for Self-Concept Scale…………………. 46 4 CFA of Factor loadings for Depression Scale………………………… 51 5 CFA of Factor loadings