The “supersizing” of foods in the context of the obesity epidemic

Little is known about an increasing trend of larger portion sizes in the United States. Increased portions of energy-dense foods, promoted by bigger-package-unit sizes and good-value meals, might be pushing the energy intakes beyond requirements, representing a higher risk for childhood obesity^1,2.

Larger portions sizes of energy-dense foods might be even more problematic among older children and adolescents. As children age, physiological cues such as hunger and satiety that help them self regulate their energy intake exert less influence, predisposing them to overeat in an environment of excess caloric availability and limited Energy expenditure^3-6.

Our research investigated:

1. if portion sizes of energy dense foods have increased from 1977 to 2006 ⁷; and
2. if a larger portion size of a certain food increases the energy intake at a meal during which that food was consumed⁸.
   We also explored socioeconomic and age-specific patterns and trends in portion sizes from 1977-78 to 2003-06 in the United States.

Study design

We studied 31,337 children and adolescent ages 2-18 from four U.S. nationally representative surveys of dietary intake data^9-13. We grouped children and adolescents in three age groups (i.e. 2-6-year-olds, 7-12-year-olds and 13-18-year-olds) and we also created three groups of race/ethnicity (i.e. non-Hispanic white, non-Hispanic African-American and Hispanic) and parent education (i.e. more than 12 years of education or less than 12 years of education). Dietary intake data from two 24-hour recalls was averaged to get per-capita estimates.

We defined a portion size as the amount of kcals, grams or milliliters from a certain food or beverage consumed at a given eating occasion. We
calculated mean portion sizes of selected foods and beverages (i.e. salty snacks, desserts, soft-drinks, fruit-drinks, French-fries, burgers, pizza and Mexican-food) and mean energy intake at eating occasions during which each selected food was consumed. Then, kcal from each selected food was divided by the total energy intake at a meal during which each food was consumed. If the proportion of the meal energy intake comprised by each food increased from 1977 to 2006, we concluded that a larger portion size of a food affected the energy intake at eating occasions.

Portion sizes of energy dense foods have increased

In 2003-2006, energy dense foods (e.g. salty snacks, desserts, fries, soft drinks, burgers, pizza, etc) represented around 38% of the daily Energy intake among adolescents 13-18 years old; 35% of the daily intake among 7-12 year-olds and 28% of the daily intake of 2-6 year-olds. Overall, portion sizes of all selected foods increased significantly from 1977 to 2006, except desserts. The increases in portion sizes of pizza were particularly pronounced in the last decade.

Energy intake is affected by larger portion sizes, especially among older children

In all age groups, we found larger portion sizes of pizza in parallel with higher energy intake at eating occasions during which pizza was consumed. Pizza was the only significant contributor to the increased energy intake among young children aged 2-6 years old. In children 7-12 years old, soft drinks and burgers together with pizza were significant contributors to the increased intake at eating occasions. Importantly, adolescents’ energy intake at eating occasions was affected by all selected foods, in line with previous findings suggesting that older children might be more susceptible to larger portion sizes than younger children. Energy intake at eating occasions was also significantly affected by larger portion sizes of pizza, especially markedly among non-Hispanic African American and Hispanic and the group of low parent education compared to the other groups.

Conclusions

Our results provide a new perspective of the effect of larger portion sizes on the total energy intake at meals. In the context of the growing obesity epidemic in the U.S. and worldwide, we identified selected energy-dense foods that have increased in portion size over the 30-year period studied. These selected foods are also important contributors of the increased energy intake at eating occasions. This research supports the need to consider targeted intervention and policy efforts that look specifically at selected foods (e.g. pizza, soft drinks) to reduce the energy intake of children and adolescents.