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Journal of Obesity
Volume 2014, Article ID 728762, 9 pages
Research Article

The Trajectory and the Related Physical and Social Determinants of Body Mass Index in Elementary School Children: Results from the Child and Adolescent Behaviors in Long-Term Evolution Study

1Department of Health, Taipei City Government, Taipei City 11008, Taiwan
2Graduate Institute of Health Policy and Management, College of Public Health, National Taiwan University, Taipei 10055, Taiwan
3Institute of Population Health Sciences, National Health Research Institutes, Miaoli County 35053, Taiwan
4School of Public Health, Chung Shan Medical University, Taichung 40201, Taiwan
5Department of Family and Community Medicine, Chung Shan Medical University Hospital, Taichung 40201, Taiwan
6Surveillance and Research Division, Health Promotion Administration, Ministry of Health and Welfare, Taichung 40341, Taiwan

Received 5 February 2014; Revised 4 June 2014; Accepted 11 June 2014; Published 8 July 2014

Academic Editor: Terry Huang

Copyright © 2014 Li-Ju Lin et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This study explored developmental trajectory patterns of BMI and associated factors. Participants included 1,609 students who were followed from age 7 to 12 years. Data collection involved annual self-administered questionnaires and records of height and weight. An ecological model was used to identify the factors associated with BMI trajectories. Group-based trajectory models and multinomial logit models were used in the statistical analysis. There were gender differences in BMI trajectories. Among boys, four BMI trajectories were normal or slightly underweight, persistently normal weight, overweight becoming obese, and persistently obese. Among girls, four BMI trajectories were persistently slightly underweight, persistently normal weight, persistently overweight, and persistently obese. The mean BMI in each trajectory group demonstrated an upward trend over time. In boys, BMI trajectories were significantly associated with after-school exercise, academic performance, family interactions, overweight parents, and father’s education level. In girls, BMI trajectories were significantly associated with television viewing or computer use, family interactions, peer interactions, and overweight parents. Children under age 7 years who are already overweight or obese are an important target for interventions. The different factors associated with BMI trajectories can be used for targeting high risk groups.