(HealthDay)—Improvements were observed in obesity-related behaviors of U.S. adolescents between 2001 and 2009, but further research is needed to explain the increase seen in body mass index (BMI) during the same time period, according to research published online Sept. 16 in Pediatrics.
Ronald J. Iannotti, Ph.D., and Jing Wang, Ph.D., of the Eunice Kennedy Shriver National Institute of Child Health and Human Development in Bethesda, Md., surveyed nationally representative samples of U.S. students aged 11 to 16 years in 2001 to 2002, 2005 to 2006, and 2009 to 2010, to examine trends in physical activity, sedentary behavior, diet, and BMI.
The researchers found significant increases in the number of days that included at least 60 minutes of physical activity across the surveys. Significant improvements also occurred in dietary patterns of adolescents, including increases in daily consumption of fruits and vegetables as well as breakfast consumption. Intake of sweets and sweetened beverages and time spent viewing television decreased. However, increases in BMI occurred during the same period. Similar patterns were observed in all racial/ethnic groups.
"These patterns suggest that public health efforts to improve the obesity-related behaviors of U.S. adolescents may be having some success," the authors write. "However, alternative explanations for the increase in BMI over the same period need to be considered."
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