Causes of increased energy intake among children in the U.S., 1977-2010

Changes in total energy intake have been reported among children and adolescents, but the extent to which the components of total energy-energy density; portion size; and the number of eating/drinking occasions (EO)-drive these changes is unknown.

The objective of the current study was to examine the relative contribution to changes in daily total energy.

Using cross-sectional nationally representative data from the Nationwide Food Consumption Survey (1977-1978); the Continuing Survey of Food Intake of Individuals (1989-1991); and the National Health and Nutrition Examination Surveys (1994-1998 and 2005-2010) for children and adolescents (aged 2-18 years), changes in total energy (kcal/day) were mathematically decomposed to determine the relative contributions of its three component parts: portion size (g/EO); energy density (kcal/g/EO); and eating/drinking occasions (n). Analyses were completed in 2012.

Over the full period, there was an increase in total energy intake (+108 kcal/day) and the number of daily eating/drinking occasions (+1.2). The average portion size per eating/drinking occasion increased between 1977-1978 and 1989-1991, and then dropped by about 85 g/EO between 1989-1991 and 2005-2010. The average energy density per eating/drinking occasion has fluctuated over time, reaching its highest level in 2005-2010 (1.24 kcal/g/EO). The decomposition results show that between 1977-1978 and 2005-2010, changes in the number of eating/drinking occasions per day and portion size per eating occasion were the largest contributors to annualized changes in daily total energy (+19 and -13 kcal/day/year, respectively). Variations in trends were observed for race/ethnicity and parental education subgroups.

These findings highlight potentially important intervention targets for reducing energy imbalances in U.S. youth.