US adults not just eating more, but more often

Over the past 30 years, US adults have been eating larger portions and eating more often, according to a new study by University of North Carolina at Chapel Hill researchers. The findings help illustrate that how Americans are eating contributes to the country’s obesity epidemic.

The study examines the combined contribution of changes in three key factors (portion sizes, food energy density, and eating frequency) on people’s total calorie consumption. The findings are published in the June 2011 issue of the journal PLoS Medicine.

In the study, the researchers analyzed individuals’ dietary intake over a 24-hr period, based on surveys of US adults taken between 1977–78, 1989–91, 1994–98, and 2003–06. They found that the average daily total energy intake, measured in calories, increased from about 1 803 kcal in 1977–78 to 2 374 kcal in 2003–06, an increase of 570 kcal.

Increases in the number of eating occasions (meals and snacks) and portion sizes of foods and beverages over the past 30 years accounted for most of the increase. Energy density (the number of calories in a specific amount of food) also accounted for some of the change, but may have decreased slightly in recent years, the researchers reported.

Looking at the changes between each survey period, portion size accounted for an annual increase in the daily total energy intake of nearly 15 kcal between 1977–78 and 1989–91, whereas changes in the number of eating occasions accounted for an increase of just 4 kcal per year. However, between 1994–98 and 2003–06, changes in the number of eating occasions accounted for an annual increase in daily total energy intake of 39 kcal, whereas changes in portion size accounted for an annual decrease of 1 kcal.

Barry Popkin, the study’s senior author and WR Kenan Jr, Distinguished Professor of Nutrition at the UNC Gillings School of Global Public Health, noted that the findings may not be completely accurate since the participants may have under- or over-reported the amount of food consumed.

“Still, these findings suggest that efforts to prevent obesity among adults in the US should focus on reducing the number of meals and snacks people consume during the day and reducing portion size as a way to reduce the energy imbalance caused by recent increases in energy intake,” said Popkin.

This topic was also addressed at the 2011 IFT Annual Meeting & Food Expo, held June 11–14 in New Orleans, In session 136 “Snacking: Insight and perspectives on contributions to the American diet,” three experts examined how snacking has taken over and its role in the growing obesity epidemic.

Although the industry is lacking a definitive definition, there is no doubt that consumers are snacking more. According to Rick Mattes, Purdue University, consumers have increased the number of snacks they are eating per day so much so that a quarter of total energy taken in is from snacks. Read more about the session in IFT Live.