Supersizing, volumetrics, or constant eating: causes of increased energy intake in US adults

Abstract

The relative effect of energy density (ED), the number of eating occasions (EO), and portion size (PS) to total energy (TE) intake are unknown. Using cross‐sectional nationally‐representative data from the Nationwide Food Consumption Survey (1977–78, n=17,464), Continuing Survey of Food Intake of Individuals (1989–91, n=8,340), and National Health and Nutrition Examination Surveys (1994–98 and 2003–06, n=9,460) for adults (aged ≥ 19 y) we mathematically decompose TE (kcal/d) to understand the relative contributions of each component ‐ PS (g/EO), ED (kcal/g/EO) and EO(#) ‐ to changes in TE over time. There was a steady increase in TE intake (+437 kcal, p<0.001) and the number of daily EO (+1.0 p<0.001) between 1977–78 and 2003–06. The average PS steadily increased between 1977–78 and 1994–98 then non‐significantly decreased between 1994–98 and 2003–06, while the average ED remained relatively stable over the 30‐year period. Between 1977–78 and 1989–91 changes in PS dominated (84.9% of the TE change), while changes in EO accounted for 37.1% of TE change. However, between 1994–98 and 2003–06 changes in EOs accounted for 88.2% and changes in PS accounted for just 22.6% of change in TE. While all three components contributed to the 30‐yr change, changes in EO and PS have consistently accounted for the greatest percent of change in total energy intake. These findings suggest a new focus for obesity prevention efforts.