Weight Status Underestimation Among Canadian Adolescents: an Important and Frequently Overlooked Aspect of the Childhood Obesity Epidemic
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Western University Scholarship@Western Electronic Thesis and Dissertation Repository 8-1-2012 12:00 AM Weight Status Underestimation among Canadian Adolescents: An Important and Frequently Overlooked Aspect of the Childhood Obesity Epidemic Mary Ellen Kuenzig The University of Western Ontario Supervisor Piotr Wilk The University of Western Ontario Graduate Program in Epidemiology and Biostatistics A thesis submitted in partial fulfillment of the equirr ements for the degree in Master of Science © Mary Ellen Kuenzig 2012 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Epidemiology Commons Recommended Citation Kuenzig, Mary Ellen, "Weight Status Underestimation among Canadian Adolescents: An Important and Frequently Overlooked Aspect of the Childhood Obesity Epidemic" (2012). Electronic Thesis and Dissertation Repository. 680. https://ir.lib.uwo.ca/etd/680 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. WEIGHT STATUS UNDERESTIMATION AMONG CANADIAN ADOLESCENTS: AN IMPORTANT AND FREQUENTLY OVERLOOKED ASPECT OF THE CHILDHOOD OBESITY EPIDEMIC (Spine title: Weight Status Underestimation among Canadian Adolescents) (Thesis format: Monograph) by Mary Ellen Kuenzig Graduate Program in Epidemiology & Biostatistics A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science The School of Graduate and Postdoctoral Studies The University of Western Ontario London, Ontario, Canada © Mary Ellen Kuenzig 2012 i THE UNIVERSITY OF WESTERN ONTARIO School of Graduate and Postdoctoral Studies CERTIFICATE OF EXAMINATION Supervisor Examiners ______________________________ ______________________________ Dr. Piotr Wilk Dr. Shauna Burke Supervisory Committee ______________________________ Dr. Anita Kothari ______________________________ Dr. Greta R. Bauer ______________________________ Dr. Kathy N. Speechley The thesis by Mary Ellen Kuenzig entitled: Weight Status Underestimation among Canadian Adolescents: An Important and Frequently Overlooked Aspect of the Childhood Obesity Epidemic is accepted in partial fulfillment of the requirements for the degree of Master of Science ______________________ _______________________________ Date Chair of the Thesis Examination Board ii Abstract Objectives: Overweight adolescents frequently fail to recognize that they are overweight. This project examines the magnitude of weight status underestimation among overweight adolescents and identifies predictors of this underestimation. Methods: Data from the Canadian Community Health Survey (2001-2010) were used. Overweight adolescents (N=11,452) reporting they were underweight or about right were classified as underestimating their weight. The time trend in underestimation and effects of individual-level characteristics on underestimation were examined using logistic regression. Multilevel analysis examined the effect of weight status of community-based reference groups. Results: For every 5 overweight male adolescents, 3 underestimated their weight; 2 of 5 overweight females underestimated. Exposure to overweight explained some of the variation in underestimation across communities among females. Conclusions: Weight status underestimation is a significant problem among overweight adolescents. Understanding how adolescents perceive their weight is an important and novel concept in maximizing the effectiveness of current approaches to adolescent obesity. Keywords adolescent, overweight, obesity, body mass index (BMI), perception, underestimation, multilevel modeling, Canadian Community Health Survey (CCHS), weight status, interval odds ratio (IOR), median odds ratio (MOR) iii Acknowledgments I would like to begin by thanking my supervisor, Dr Piotr Wilk, for his continued guidance over the past two years. His mentorship has proven invaluable throughout this project. Dr Wilk has encouraged work beyond the thesis writing itself, supporting poster and oral presentations in Lyon, France and Edmonton, Alberta—advising on the abstracts and applications for these international and national conferences. Without him, none of this would have been possible. I would also like to thank Dr Greta Bauer of my supervisory committee for her insight and encouragement along the way. This Master’s thesis could not have been written without the professors in the Department of Epidemiology & Biostatistics. Throughout the many courses I have taken, I have gained a wealth of knowledge in all aspects of epidemiological research which allowed for the final document. I thank them all for sharing their knowledge and skill. I extend sincere thanks to my colleagues in the Department of Epidemiology & Biostatistics. You have enhanced and broadened my skills and experiences as an individual. In addition, I will cherish the many fond and memorable moments we have shared as I go forward in life. Financial support for this project has been provided by the Children’s Health Research Institute and the Graduate Thesis Research Fund. This funding has provided me with opportunities far beyond what I ever could have expected. Lastly, I would like to thank my parents and extended family for the continued love and support. iv Table of Contents CERTIFICATE OF EXAMINATION ........................................................................... ii Abstract .............................................................................................................................. iii Acknowledgments.............................................................................................................. iv Table of Contents ................................................................................................................ v List of Tables ..................................................................................................................... ix List of Figures ................................................................................................................... xii List of Appendices ........................................................................................................... xiii List of Abbreviations ....................................................................................................... xiv Chapter 1 ............................................................................................................................. 1 1 Introduction & Literature Review .................................................................................. 1 1.1 Introduction ............................................................................................................. 1 1.2 The Childhood Obesity Epidemic in Canada.......................................................... 2 1.2.1 Prevalence of Overweight and Obesity ....................................................... 2 1.2.2 Risk Factors for Adolescent Overweight & Obesity .................................. 4 1.2.3 Health Risks & Adolescent Obesity ........................................................... 6 1.3 Weight Status Underestimation ............................................................................ 10 1.3.1 Implications of Weight Status Underestimation ....................................... 10 1.3.2 Prevalence of Weight Status Underestimation ......................................... 15 1.3.3 Causal Pathways ....................................................................................... 20 1.3.4 Challenges in Comparing Studies of Weight Status Underestimation ..... 22 1.3.5 Predictors of Weight Status Underestimation among Adolescents .......... 26 1.4 Summary ............................................................................................................... 31 Chapter 2 ........................................................................................................................... 33 v 2 Objectives & Hypotheses ............................................................................................. 33 2.1 Objectives ............................................................................................................. 33 2.2 Hypotheses ............................................................................................................ 34 Chapter 3 ........................................................................................................................... 36 3 Methods ........................................................................................................................ 36 3.1 Data Source ........................................................................................................... 36 3.1.1 Content of the CCHS ................................................................................ 36 3.1.2 Sampling Design ....................................................................................... 37 3.1.3 Study Population ....................................................................................... 38 3.2 Measurement Instruments ..................................................................................... 42 3.2.1 Perceived Weight Status ........................................................................... 42 3.2.2 Severity of Overweight ............................................................................. 43 3.2.3 Age ...........................................................................................................