«A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Environmental Health Sciences) in the ...»
Body Image Perception and Adiposity in School-Age Children
A dissertation submitted in partial fulfillment
of the requirements for the degree of
Doctor of Philosophy
(Environmental Health Sciences)
in the University of Michigan
Associate Professor Eduardo Villamor, Co-Chair
Associate Professor John D. Meeker, Co-Chair
Associate Professor Ana Baylin
Associate Professor Joyce M. Lee
Professor Carlos F. Mendes de Leon “The journey is the reward” ~ Chinese Proverb © Ofra Duchin 2013 Dedication To my parents, Yona and Ygal To my husband, Ran ii Acknowledgments I owe my deepest gratitude and respect to my advisor and mentor, Eduardo Villamor.
I am sincerely grateful for the opportunity to learn from your insightful guidance, continuous enthusiasm, rigorous approach to research, and extensive knowledge.
Thank you for all the long meetings, the detailed emails, and the numerous red-pen comments.
Being your student has been a great privilege and a once-in-a-lifetime experience.
I am deeply grateful to my doctoral committee members, Ana Baylin, Joyce Lee, Carlos Mendes de Leon, and John Meeker And to my co-authors in Colombia, Mercedes Mora-Plazas and Constanza Marin, For your genuine interest, valuable advice and skillful comments that greatly contributed to my thesis.
The Bogotá School Children Cohort Study is currently sponsored by the ASISA Research Fund at the University of Michigan. The study protocol was approved by the Ethics Committee of the National University of Colombia Medical School. The Health Sciences and Behavioral Sciences Institutional Review Board at the University of Michigan approved the use of data from the study.
iii Table of Contents Dedication ii Acknowledgements iii List of Tables v List of Figures vi List of Appendices vii Chapter 1: Introduction Overview
Table 2.3: Correlations of body image perception components in school-aged children 24 Table 3.
1: Characteristics of school children and their mothers at time of recruitment 40
Table 3.3: Estimated BMI change from ages 6 to 14 years according to body image dissatisfaction in school-age children, stratified by weight status of the child at baseline 42 Table 4.
1: Characteristics of school-age children and their mothers at recruitment 60
Figure 3.1: Estimated BMI change from ages 6 to 14 years according to body image dissatisfaction in school-age children, stratified by weight status at baseline 43
Appendix 3: Questions Related to Body Image Perception which were presented to children and mothers in the Bogotá School Children Cohort (2006 Questionnaires, English translation) 78
Overview During the past years, countries in Latin America have been undergoing a nutritional transition as part of rapid demographic and economic changes, which resulted in an increase in the prevalence of obesity in the region(1-3). Economic development of a country usually brings about an increase of nutrient-poor processed foods that are high in their caloric intake, alongside with decreased opportunities for physical activity. Together, these processes impact the energy balance of an individual and lead to excessive weight gain over time. The rapid increase in prevalence of childhood obesity is of a special concern since it has both immediate and longterm health consequences(4-9). Therefore, there is a pressing need to adequately characterize its causes. Since these causes may be different across populations undergoing different stages of economic development and nutrition transition, they need to be considered carefully when investigating the predictors of childhood obesity in different settings around the world.
Weight status in children and adolescents is affected by various influences (10-14), including genetic background, sociodemographic characteristics such as sex, age, pubertal stage, and socioeconomic status. Additional important correlates of childhood obesity include familial, school and built environments, dietary patterns, level of engagement in physical activity, and many others. While dietary intake and physical activity are most likely direct predictors of obesity in children, there are also important psychological factors associated with it, such as body image perception. Several cross-sectional studies showed a positive correlation between body dissatisfaction and body mass index in various age groups and different populations(15In other words, overweight and obese children, or parents to children from these weight groups, tend to perceive the child as being thinner that he or she actually measures, and also to desire a slimmer body image for the child, compared to normal-weight and thin peers.
In contrast, it has been suggested that body image perception or dissatisfaction may be a predictor of changes in one's weight. Dissatisfaction with physical appearance may result in intentional behaviors aimed toward weight loss or gain. body image dissatisfaction may also lead 1 to excessive weight gain through unintentional mechanisms. For example, it is possible that weight-related concerns and behaviors are reflected in child feeding practices(18) and family weight-talk in parents to children.(19), while the child's own dissatisfaction could lead indirectly to increased weight gain through increased sedentary behavior,(20, 21) social isolation, and depression,(22, 23) or through the emergence of weight-related anxiety, which may contribute to excessive weight gain over time.(24) Due to their study design, cross-sectional studies cannot address the possibility of reverse causality between weight status and body image perception, and cannot determine whether body image dissatisfaction preceded overweight or vice versa. Prospective studies are required, therefore, to disentangle this 'chicken-and-the-egg' question in order to enhance our understanding of the phenomenon of childhood obesity in general, and specifically in populations undergoing the nutrition transition, where dramatic changes in both obesity rates and exposure to Westernized body image concepts take place.
An additional factor associated with childhood overweight is parental perception of the child’s weight status(25, 26), which may be potentially distorted, as it depends on cultural background(27), socioeconomic status (28) and parental weight(29). To the best of our knowledge, body image dissatisfaction has not been extensively examined as a predictor for development of adiposity in prospective studies among school-age children. Furthermore, characterization of the predictors of body image dissatisfaction is lacking in this early age groups in general, and specifically in Latino children undergoing the nutrition transition.
This work was conducted in the context of the Bogotá School Children Cohort, an ongoing cohort of 3,202 schoolchildren and their mothers started in 2006 in Bogotá, Colombia.
We explored potential correlates of body image perception in school-age children, and examined possible associations between maternal perceptions of the child and between body image perception in the children. In addition to this cross-sectional investigation of children's body image perception at time of recruitment, we prospectively investigated whether body image dissatisfaction in either the children or their mothers predicts development of childhood adiposity. Successful realization of this research will demonstrate a possible relation between body image dissatisfaction and growth trajectories in school-age children. It will also provide 2 novel insights into the causal chain leading to development of childhood adiposity in countries undergoing the nutrition transition. Body image dissatisfaction is potentially modifiable and can be addressed at the level of the individual or the family, or as part of the social context for the individual among his or her peers(30). Therefore it is crucial to determine whether adversely affect weight trajectories in children over time. Comprehensive understanding of its impact on health outcomes has important policy implications as it will provide the basis for future interventions.
3 Specific Aims
The overarching goal of this work is to identify correlates of body image perception among school-aged children from Colombia, a country undergoing the nutrition transition, and to determine the association of body image perception with weight trajectories in these children.
Aim 1: To identify sociodemographic, anthropometric and maternal correlates of body image perception among school-aged children from Colombia, a country undergoing the nutrition transition, and to characterize the potential contribution of psychosocial constructs of body image perception to the concept of body image dissatisfaction in the child.
Aim 2: To investigate whether body image dissatisfaction predicts development of adiposity in school-age children. To this end, we examined the associations between children's body image dissatisfaction at baseline and between their weight trajectories over a 2.5 year follow-up period in a cohort study of school-age children from Bogotá, Colombia.
AIM 3: To examine the relation between maternal BID and children’s weight changes in a longitudinal study. Specifically, to investigate whether a mother’s dissatisfaction with her own body image or with that of her child at the time of recruitment would predict weight changes in the children over time.
4 Summary of Chapters
This work contributes to the existing knowledge of body image perception in children by examining a wide range of correlates of body image dissatisfaction among low- and middleincome school-age children from a population experiencing the nutrition transition, and by prospectively investigating body image dissatisfaction in either child or mother as predictors of weight trajectories in these children according to their sex and weight at time of recruitment.
Chapter 2 presents a cross-sectional examination of potential correlates of body image perception among children enrolled in the Bogotá School Children Cohort, an ongoing study of a nutrition and health of primary schoolchildren in Bogotá, Colombia. These correlates included sociodemographic and anthropometric characteristics of both mother and child. In this chapter, we also assessed the contribution of various psychosocial constructs of body image perception, as reported by both the children and their mothers, to conceptualization of body image dissatisfaction in the children. In chapter 3 we determined whether body dissatisfaction in the child at time of recruitment predicts weight trajectories in children during follow-up, according to their sex and baseline weight status. We further examined maternal dissatisfaction with body image of herself or her child as two separate predictors of weight trajectories in the children.
This investigation is described in detail in chapter 4. In the fifth and final chapter we summarize the main findings of the thesis, discuss their public health implications and provide suggestions for future research.
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