Q: Do you think these calorie decreases could make a significant impact on childhood obesity rates?
A: This study shows a substantial decline in calorie consumption and that’s an important first step. At the same time, obesity rates actually increased among boys and have not changed among girls. There are many possible explanations for this that are not addressed by the CDC study, including changes in kids’ physical activity levels or underreporting of dietary intake.
Q: What’s behind the decline? Do these findings mean that kids are eating healthier?
A: The CDC study suggests that kids are consuming less refined sugar, fewer carbohydrates, and more protein than they used to, which is meaningful. Yet we also know that kids consume an excessive amount of “empty calories”—those that come from foods and drinks that pack a lot of calories but offer few or no nutrients. For example, another study shows that in 2009-10, which was the final year of the CDC study period, about a third of all the calories kids consumed came from added sugars and solid fats.*
Q: Dr. Popkin, your research team recently developed a way to track the flow of food and beverage products that are sold, purchased, and consumed by Americans. Could that system tell us more about which foods and drinks kids are cutting back on? Could it help explain the decline in calories reported by the CDC?
A: We are studying this now and have identified two important trends. First, that people are consuming fewer calories outside of the home—in restaurants or fast food outlets. And second, that people are consuming fewer sugary drinks. More information about these findings will be released in summer 2013.
Q: Dr. Wang, a recent study of yours found that if children in the United States eliminated an average of 64 excess calories per day, we would achieve goals set by the federal government for reducing obesity rates by 2020. Doesn’t the CDC study suggest that kids are already doing this, and more?
A: If the calorie declines reported in the CDC study are real and accurately measured, it means we’re heading in the right direction. But we can’t say whether such declines mean that we’ll reach our nation’s goals for reducing childhood obesity rates. Our study, which found that children would need to eliminate 64 excess calories per day, was based on data from 2007-08. If we had made our projections using 1999-2000 data, which were the starting point for the CDC study, we’d likely have concluded that kids needed to eliminate more than 64 calories per day.
Q: The CDC study didn’t link the decrease in calorie consumption with changes in obesity rates, but can we anticipate that kids’ obesity rates will decline based on the trends identified in this study?
A: If a substantial decline in calorie intake continues among children and teens, we would expect to see a small decline in obesity rates, but that doesn’t mean our problem is solved. The CDC study is encouraging, but childhood obesity rates are still much too high and the epidemic is particularly severe in communities of color. The CDC’s findings should inspire all of us—schools, governments, the food and beverage industry, health care providers, parents—to work together to help families and children eat healthier and be more active.
*Slining, M. M., Popkin, Barry M. (in press). "Trends in intakes and sources of solid fats and added sugars among US children and adolescents: 1994-2010." Pediatric Obesity.