| In the early-21st century, we have a well-documented obesity epidemic in the United States, and it is found increasingly in much of the industrialized world. The rise in the prevalence of childhood obesity in particular is most striking and disconcerting for our future. This study seeks to examine the relationships between physical activity, dietary behavior, and BMI in children and adolescents using a sample data set of 5,101 survey participants in the 2005-2006 National Health and Nutrition Examination Survey (NHANES). In general, the findings are consistent with the findings in the published literature. There does appear to be a statistically significant relationship between physical activity and BMI; however, the strength of the relationship and its predictive value are weak. There does not appear to be a statistically significant relationship between lunches and/or breakfasts eaten at school and BMI. There does appear to be a statistically significant relationship between BMI and physical activity combined with dietary behavior, but the linear regression model tested to have a very weak predictive power. The primary limitations of the study are the broad age range used in both independent variables, and the lack of direct measurement of physical exercise and dietary behavior used in NHANES. In conclusion, the data in NHANES is found to be consistent with the evidence in the published literature, that is, that there is very little evidence to show that increased physical exercise, decreased sedentary behavior, and/or better dietary intake has a statistically significant impact on childhood obesity and BMI. What is needed to truly assess the impact of these variables on BMI is additional scientific evidence: large, well-designed studies with samples that are representative of the general population, that include long term follow-up; and interventions which measure direct effect on physical exercise and diet, and therefore their relationship to BMI. |
