Severe obesity on the rise among U.S. children

Severe obesity on the rise among U.S. children click to enlarge Asheley Skinner Cockrell, PhD

Despite a CDC report to the contrary in recent weeks, a new analysis led by a UNC researcher finds that all classes of obesity in children have increased over the last 14 years, as well as a troubling upward trend in the more severe forms of childhood obesity. The study, published in JAMA Pediatrics on April, 7, 2014, has received widespread national media attention.

The study’s lead author, Asheley Cockrell Skinner, PhD, assistant professor of pediatrics in the UNC School of Medicine, explains the findings in this Q&A.

What are the main findings of the study?

There are two critical findings of our study. The first is that more severe forms of obesity are increasing among children. This is particularly true among school-aged girls (ages 6-11) and adolescent boys (ages 12-19).

The second is in the context of the CDC report published several weeks ago indicating that obesity in young children was declining. Our study used the same data and approach, but we extended the timeframe back an additional four years, which represents the full 14 years of National Health and Nutrition Examination Survey (NHANES) data available (1999 to 2012).

It is important to note that the CDC’s findings are technically correct when using a 10-year timeframe (2003 to 2012), and our numbers match theirs. However, the studies’ conclusions differ based on the researchers’ decisions about which timeframe to use. We chose the 14-year timeframe, because we felt it prudent to use all available data rather than a subset—and when taking that long-term view, there is actually no indication of a decline in obesity in any group from 1999 to 2012.

How is it possible that both studies, reporting oppositional findings, are correct?

Looking at the 2003 data, there was an unusual uptick in obesity reported in young children (ages 2 to 5). We can’t explain this anomaly, whether there’s a measurement error or if preschoolers happened to be heavier in 2003. But if one uses 2003 as the starting point and tracks the rates of obesity through 2012, the data support a decline in obesity among children in that age group. Using the entire 14-year data set, however, this odd spike in obesity “balances out,” and we see that rates of obesity among this age group remain unchanged.

I think it is also important to note that the CDC’s report was clear that overall obesity rates in all other age groups remain unchanged.

Why challenge the CDC’s findings?

This study wasn’t about challenging the CDC’s findings. First of all, our study was conducted and written months before the CDC’s findings were reported, so it was not done in response to them. But, with both studies out, I thought it important to put those findings into context in order to clarify public perception about childhood obesity. We’ve seen obesity rates climb even as we developed more and more interventions. Clearly, we need to be considering ways to radically change the environment in ways that can promote health.

With so many youth on a trajectory to developing chronic diseases like diabetes, hypertension, and cardiovascular disease, this is an urgent public health issue. We cannot afford to lose any momentum. We need the public dialogue to continue. I worry that hearing that obesity among young children has declined 43 percent sends the wrong message when our study clearly demonstrates that all classes of obesity in U.S. children have increased over the last 14 years.

Were any of the findings unexpected?

I don’t think any of our findings were unexpected. The reasons for childhood overweight and obesity in the U.S. are complex, and there has been little change in the overall environment. So, we did not expect to see any declines in obesity.

What should clinicians and patients take away from your report?

I believe that most of our approaches to caring for overweight kids should be things we do for every child—encourage activity, ensure access to healthy foods, and help families be healthy overall. Most kids are very healthy, even if they meet the definitions for obesity. That said, the most extreme levels of obesity can be problematic even for children and adolescents.

What are the implications / take-home message?

One of the most important take-home messages is that we need to be cautious in jumping to conclusions that childhood obesity has improved. Although the number of kids who meet the general criteria is relatively stable, that doesn’t tell us much about them, and it appears obesity may be worse for some groups.

Even more important, I think the study shows that we must continue our efforts to ensure a healthy environment for kids. Rather than focus only on obesity in general, we need to reach out to all kids to prevent significant weight gain of the level that does put their health at risk.

What recommendations do you have for future research as a result of this study?

Future research needs to focus on ways to change the overall environment. Despite many efforts to reduce obesity, we are not seeing much change, which indicates that broader environmental changes are needed to ensure all children have opportunities for activity and access to healthy foods, regardless of weight.

Also, because it’s clear that weight is difficult to change, we need to shift to a focus on health, and ensuring kids of all sizes are healthy and have access to healthy foods and activities.

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This Study in the News

Reuters, U.S. childhood obesity rates have increased since 1999: study

USA Today, No real progress on child obesity, latest report says

NBC News, Severe obesity may be on the rise in kids (VIDEO: Childhood obesity: no major shift?)

CBS News, Severe childhood obesity on the rise in U.S., study shows

CNN, Severe obesity in kids on the rise