Location: Children's Nutrition Research CenterTitle: Changes in weight over the school year and summer vacation: Results of a 5-year longitudinal study Author
Submitted to: Obesity
Publication Type: Abstract Only
Publication Acceptance Date: 10/2/2011
Publication Date: 11/1/2011
Citation: Palcic, J., Johnston, C.A., Brooks, S., Silberstein, L.K., Woehler, D.L., Foreyt, J.P. 2011. Changes in weight over the school year and summer vacation: Results of a 5-year longitudinal study [abstract]. Obesity. 19:S141. Interpretive Summary:
Technical Abstract: Some evidence suggests that children have relatively higher increases in weight during the summer months compared to the school year. In order to further examine the impact of the school and summer environment on children's weight, we conducted a 5-year longitudinal study examining changes in standardized BMI (zBMI) of students entering kindergarten. Heights and weights were obtained at the beginning and end of each school year. Participants included 3588 ethnically diverse (Caucasian: 27.2%, Black: 29.0%, Hispanic: 26.4%, Asian 17.4%) students who were between the ages of 5 and 7. A significant difference in change in zBMI during the school and summer months was found (t=-9.45, p<.001), with zBMI decreasing during the school year and increasing during summer. Post hoc analyses were conducted based on weight classifications, and students who were overweight and obese demonstrated the pattern of zBMI decrease during the school year and increase during the summer months (t=-9.21, p<.001 and t =-13.23, p<.001; respectively). Normal weight students increased their zBMI during both time periods, though increases were greater during the summer months compared to the school year (t=-4.04, p<.001). The period of the year spent in school seems to have a beneficial impact on students' weight, especially for students who are overweight or obese. However, these results are alarming because weight gain during elementary school years occurs primarily during the months of summer.