Obesity Rates Climbing in US Youth, Especially in Adolescents

Pam Harrison

April 27, 2016

Contrary to several previous reports, there is no evidence that obesity rates are declining in children or adolescents in the United States, and, in fact, the trajectory is continuing to climb, especially rates of severe obesity among adolescents, according to the latest data from the National Health and Nutrition Examination Survey (NHANES) 1999–2014.

Even though there has been the odd glimmer of hope that obesity rates are stabilizing among certain pediatric groups — for example, one study suggested a modest decline among preschoolers in the United States (JAMA. 2014;311:806-814) and data from elsewhere suggest obesity rates may be falling in certain socioeconomic groups in other developed countries — obesity rates among US children and adolescents are going nowhere but up, the authors of the new analysis stress.

"We saw a clear, statistically significant increase in all classes of obesity from 1999 through 2014 and most notably, all classes of obesity increased over time for adolescents of both sexes," say Asheley Skinner, PhD, Duke Clinical Research Institute, Durham, North Carolina, and colleagues in their paper, published in the May issue of Obesity.

However, the author of an accompanying editorial, William Dietz, MD, PhD, director of the Sumner M Redstone Global Center for Prevention and Wellness at the Milken Institute School of Public Health, George Washington University, Washington, DC, begs to differ.

Citing the previously mentioned study, which documented a 5.5% decline in the prevalence of obesity among 2-to-5-year-olds in the United States from 2003–2004 data, he says this observation was confirmed by another analysis of the much larger Pediatric Nutrition Surveillance System (PedNSS), which again showed there had been significant decrease in the prevalence of obesity among 2-to-4-year-olds between 2008 and 2011 (MMWR Morb Mort Wkly Rep. 2013;62;629-634).

Dr Dietz also points out that there has been a decline in availability of sugary drinks and fast food over the past decade, which would fuel expectations that the prevalence of obesity in 2- to 19-year-olds in the United States would at least have plateaued.

"The net effect of these observations makes it hard to agree with the conclusion of Skinner et al that 'there is no evidence of a decline in obesity prevalence in any age group, despite substantial clinical and policy efforts targeting the issues,' " Dr Dietz writes.

Most Up-to-Date Analysis of US Children

Dr Skinner and colleagues analyzed NHANES data from 1999 to 2014 to provide the most up-to-date analysis of the national prevalence of obesity among children and adolescents in the United States.

All children between the ages of 2 and 19 years who participated in the surveys were included in the analysis.

"Weight status was defined using measured height and weight," Dr Skinner explained. Overweight was defined as ≥85th percentile for age- and sex-specific body mass index (BMI) while obesity was defined as being ≥95th percentile — so-called class I obesity.

Class II obesity was defined as obesity that was ≥120% of the 95th percentile, or a BMI ≥35, whichever was lower, while class III obesity was defined as being ≥140% of the 95th percentile, or a BMI of ≥40, whichever was lower.

In the 2013–2014 sample, over one-third, or 33.4%, of the sample was overweight; 17.4% met criteria for class I obesity; and 6.3% of the sample met the criteria for class II obesity.

And some 2.4% of the cohort met the criteria for class III obesity.

As the authors point out, these categories are not mutually exclusive, in that the 17% of the cohort with class I obesity are included in the 33% of the cohort who were overweight.

Prevalence of Obesity for 2013—2014 by Age

Age (y) Overweight (%) Class I obesity (%) Class II obesity (%) Class III obesity (%)
2–5 25 9.2 2.1 0.2
6–11 33.3 17.9 4.6 1.1
12–19 37.4 20.9 9.5 4.3

Compared with whites, obesity rates were also higher among black and Hispanic children and adolescents, at least in the 2013–2014 cohort.

In that cohort, 37.1% of blacks and 41.8% of Hispanics were overweight compared with 29.5% of whites.

Perceived Decline Overstated

Asked by Medscape Medical News how previous reports had indicated a decline in the prevalence of obesity in preschoolers, Dr Skinner said the media had honed in on the one positive finding to emerge from the study.

In that study, there was a dip in obesity among the 2-to-5-year-olds from 13.9% in 2003–2004 to 8.4% in 2011–2012.

"However, the researchers who did that analysis were very careful not to overstate that one finding," she explained.

"And we did not see much change in obesity rates in this age group at all in either girls or boys when using all data from 1999 to 2014," Dr Skinner stressed.

All Agree Prevalence of Severe Obesity Among Adolescents Striking

The more important part of the current study is the striking prevalence of class II obesity among adolescents, which approached 10% in the sample of 2013–2014, Dr Skinner observed.

"Especially in adolescents, we are already seeing a higher risk of diabetes and the cardiometabolic syndrome in the more severe classes of obesity," she noted.

"And when we think about more severe obesity, that is the kind of obesity we expect to continue or perhaps to worsen into adulthood, and it's the higher classes of obesity that you most worry about not being able to improve."

And Dr Skinner does not disagree with Dr Dietz on one point; the latter suggests that primary-care pediatricians are poorly prepared to treat obesity, despite the fact that the average primary-care practice may have up to 50 pediatric patients with severe obesity.

"Perhaps for a child who presents with relatively mild excess weight, pediatricians can have a lot of influence," Dr Skinner suggested.

"But when you start talking about severe obesity, we know we need intensive intervention, and that's something that primary-care providers aren't prepared to do."

"The 4.5 million children and adolescents with severe obesity will require novel and intensive efforts for long-term obesity improvement," she and her colleagues conclude.

Commenting on the study, Elsie Taveras, MD, MPH, a spokesperson for the Obesity Society, called for more effective, cost-efficient, and standardized approaches and services to manage children with the most severe obesity.

"Right now, our options for the treatment of childhood obesity include multidisciplinary medical programs that often do not offer specific approaches for children with the most severe obesity, unless the programs include bariatric surgery," she said in a statement.

"This research emphasizes the urgency with which we must develop and validate a reimbursable standard of care for severe obesity in children and adolescents," she concludes.

The study authors and Dr Dietz have no relevant financial relationships.

Obesity. 2016;24:1116–1123. Article, Editorial

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