Energy density, portion size, and eating occasions: contributions to increased energy intake in the United States, 1977-2006

• Published in: PLoS medicine 2011-06, Vol.8 (6), p.e1001050-e1001050
• Main Authors: Duffey, Kiyah J, Popkin, Barry M
• Format: Article
• Language: English
• Subjects: Adult; Algorithms; Body mass index; Cross-Sectional Studies; Decomposition; Diet; Drinking; Eating; Energy Intake; Equilibrium (Physiology); Feeding Behavior; Female; Food; Food habits; Food portions; Forecasts and trends; Human physiology; Humans; Ideal Body Weight; Male; Medicine; Middle Aged; Nutrition; Nutrition research; Nutrition Surveys; Obesity; Obesity - epidemiology; Obesity - prevention & control; Physiological aspects; Poverty; United States - epidemiology; United States Department of Agriculture; Weight control
• ISSN: 1549-1676; 1549-1277; 1549-1676
• DOI: 10.1371/journal.pmed.1001050

Competing theories attempt to explain changes in total energy (TE) intake; however, a rigorous, comprehensive examination of these explanations has not been undertaken. Our objective was to examine the relative contribution of energy density (ED), portion size (PS), and the number of eating/drinking occasions (EOs) to changes in daily TE. Using cross-sectional nationally representative data from the Nationwide Food Consumption Survey (1977-78), Continuing Survey of Food Intakes of Individuals (1989-91), and National Health and Nutrition Examination Surveys (1994-98 and 2003-06) for adults (aged ≥19 y), we mathematically decompose TE (kcal/d) to understand the relative contributions of each component-PS (grams/EO), ED (kcal/g/EO) and EO(number)-to changes in TE over time. There was an increase in TE intake (+570 kcal/d) and the number of daily EOs (+1.1) between 1977-78 and 2003-06. The average PS increased between 1977-78 and 1994-98, then dropped slightly between 1994-98 and 2003-06, while the average ED remained steady between 1977-78 and 1989-91, then declined slightly between 1989-91 and 1994-98. Estimates from the decomposition statistical models suggest that between 1977-78 and 1989-91, annualized changes in PS contributed nearly 15 kcal/d/y to increases in TE, while changes in EO accounted for just 4 kcal/d/y. Between 1994-98 and 2003-06 changes in EO accounted for 39 kcal/d/y of increase and changes in PS accounted for 1 kcal/d/y of decline in the annualized change in TE. While all three components have contributed to some extent to 30-y changes in TE, changes in EO and PS have accounted for most of the change. These findings suggest a new focus for efforts to reduce energy imbalances in US adults.