Jan. 23, 2014

All those people who’ve been telling us for years that we should eat more healthy foods and cut our calories – stop, take a moment, and celebrate.

It appears that we actually listened.

A new, extensive study from The University of North Carolina at Chapel Hill’s Gillings School of Global Public Health claims that it wasn’t the Great Recession or any economic downturn that created a leveling of U.S. obesity rates (with some declines in certain subpopulations), as other scholars have suggested. Rather, the leveling and decline started well before that — in good economic times — and has continued. The reason likely is not economics as much as the result of more information and efforts aimed at producing healthier food choices and eating habits.

The study, “Turning point for US diets? Recessionary effects or behavioral shifts in foods purchased and consumed,” was posted online Jan. 15 in The American Journal of Clinical Nutrition.

Dr. Shu-wen Ng

Dr. Shu-wen Ng

“We found U.S. consumers changed their eating and food purchasing habits significantly beginning in  2003, when the economy was robust, and continued these habits to the present,” said Shu-wen Ng, PhD, research assistant professor of nutrition at UNC’s Gillings School of Global Public Health and the study’s first author.

“These changes in food habits persisted independent of economic conditions linked with the Great Recession or food prices,” Ng said. “Between 2003 and 2010, the calorie consumption was declining at an average annual rate of about 34 calories per day among children ages 2 to 18 years (compared to an average annual rate of decline of only 14 calories per day among adults). The declines in food purchases between 2000 and 2011, after adjusting for all the economic changes, was also at an average annual rate of 34 calories/capita/day per year among households with children.”

Ng added that this dramatic turn in dietary behavior is more likely the outcome of sustained and persistent public health efforts aimed at raising awareness about the importance of healthy eating, providing better information about food choices and discouraging unhealthy dietary choices. Additionally, the researchers found that the proportional decline in calories was greatest among calories from beverages.

The researchers utilized both nationally representative dietary intake data along with longitudinal data on daily food purchases from hundreds of thousands of Americans. The study samples included combined data sets from the National Health and Nutrition Examination Survey (NHANES), which covered households comprising 13,422 children and 10,791 adults from 2003 to 2011; and the Nielsen Homescan Panel, which contains food purchase data from 57,298 households with children and 108,932 households without children.

Researchers then analyzed how much of the decline was the result of the Great Recession and the year of large increases in food prices preceding the recession. If one only considered the impact of recession-related increases in unemployment, the study showed that each 1 percent increase in the unemployment rate in the area where respondents lived was associated with a two to four kcal/capita/day increase in calories purchased.  This is small relative to the major declines that occurred over time. 

Dr. Barry Popkin

Dr. Barry Popkin

“This analysis is significant as we found the largest declines were among children, said Barry Popkin, PhD, W.R. Kenan Jr. Distinguished Professor of nutrition at the UNC Gillings School and co-author of the study. “However, these declines did not occur uniformly. There were no significant declines in caloric intake observed among adolescents (ages 12 to 18 years), non-Hispanic black children and those whose parents did not complete high school. This suggests that certain subpopulations are still unable or unwilling to make these dietary changes.”  

While Popkin noted that the specific contributors for these changes in behavior are not quantifiable, he suggested that greater attention by the public health community and journalists to obesity overall, particularly to soft drinks and other high-calorie sugary beverages and the changes made by food companies or retailers may have produced a significant rise in awareness among consumers about the role of food, particularly when it comes to caloric beverages in affecting obesity and health.

The complete study can be found online.

The research was supported by grants from the Robert Wood Johnson Foundation and the National Institutes of Health.

Gillings School of Global Public Health contact: David Pesci, director of communications, (919) 962-2600 or dpesci@unc.edu.
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