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Developmental pathways leading to obesity in childhood
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by Samar Hejazi, V. Susan Dahinten, Sheila K. Marshall and Pamela A. Ratner
Abstract
Keywords
Findings
Authors
What is already known on this subject?
What does this study add?
Abstract
Background
Researchers have yet to provide a comprehensive explanation of the variability in the development of childhood obesity, owing in part to the dearth of longitudinal studies. Such an understanding would contribute to the improvement of approaches for the primary and secondary prevention of childhood obesity. This study identifies, in a representative sample of Canadian children, age-related patterns of overweight and obesity between toddlerhood and childhood.
Data and methods
The data are from cycles 2 through 5 (1996/1997 to 2002/2003) of the National Longitudinal Survey of Children and Youth. The sample comprised children aged 24 to 35 months at baseline, who were followed biennially over six years. Group-based mixture modelling analyses (using SAS PROC TRAJ) were conducted to identify the sex-specific developmental trajectories of body mass index (BMI).
Results
Group-based modelling identified four BMI trajectories for the girls (stable normal BMI, early declining BMI, late declining BMI, and an accelerating rise to obesity) and three for the boys (stable normal BMI, transient high BMI, and a J-curve rise to obesity)..
Interpretation
Identifying distinct, sex-specific BMI trajectories is valuable in understanding pathways through which a child may develop obesity. These findings have implications for further research and practice, in particular, that no single approach can be used to prevent or reduce levels of obesity.
Keywords
body mass index, child development, trajectories, health surveys, longitudinal studies
Findings
The prevalence of childhood overweight and obesity has been increasing in Canada and globally, among boys and girls of all ages, social classes, ethnic groups and races. Based on data from the 1998/1999 Canadian National Longitudinal Survey of Children and Youth, 19% of children aged 2 to 11 were overweight, and 18% were classifi ed as obese. The rising prevalence of obesity in children and adolescents raises concern about conditions and diseases associated with excess weight. Paediatric obesity can affect short- and long-term physical and psychosocial health, and is likely to contribute to adult-onset morbidity. [Full text]
Authors
Samar Hejazi (1-604-822-7614; Samar.Hejazi@nursing.ubc.ca), Susan V. Dahinten (1-604-822-7437; Susan.Dahinten@nursing.ubc.ca) and Pamela A. Ratner (1-604-822-7427; pam.ratner@ubc.ca) are with the School of Nursing, and Sheila K. Marshal (1-604-822-5672; smarshal@interchange.ubc.ca) is with the School of Social Work at the University of British Columbia, Vancouver, British Columbia, V2Y 1Y1.
What is already known on this subject?
- The prevalence of obesity among children is increasing.
- Certain patterns of adiposity rebound tend to be related to the development of obesity.
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Few longitudinal studies have explored variations in body mass index (BMI) trajectories among children, and those that have done so combined boys and girls.
What does this study add?
- Based on six-year BMI trajectories starting at ages 24 to 35 months, four subgroups of girls and three subgroups of boys were identified.
- The majority of children were in the normal BMI range throughout the six years.
- By the end of the period, 14% of the girls and 11% of the boys were in the obese BMI range.
- Another 22% of the girls and 19% of the boys had been obese at some point in the six years, but by the end of the period were in the normal range for their age and sex.
- Group-based modelling provides an alternative approach to analysing longitudinal BMI data for children.
