Too Soon to Celebrate: Obesity Rates Continue Up in US Youth

Pam Harrison

February 28, 2018

Obesity rates in American youth continue to rise, with over one third of children and adolescents ages 2 to 19 years now being overweight or obese despite widespread efforts to curb the burgeoning tide of obesity among the young, new research shows.

The study was published online February 26 in Pediatrics.

"About 4 years ago, there was evidence of a decline in obesity in preschoolers," said lead author Asheley Cockrell Skinner, PhD, associated professor of population health sciences, Duke Clinical Research Institute, Durham, North Carolina, in a statement by her institution.

"It appears any decline that may have been detected by looking at different snapshots in time or different data sets has reversed course," she added.

"The long-term trend is clearly that obesity in children of all ages is increasing," Skinner concludes.

As previously reported by Medscape Medical News, obesity rates did appear to be falling among preschoolers, as shown most recently in a study in children aged 2 to 4 years living in low-income households who took part in the Special Supplemental Nutrition Program for Women, Infants, and Children.

That, however, no longer appears to be the case, and particularly not in young children.

Sharp Increase in Class I Obesity in 2 to 5 Year Olds

In the current analysis, researchers from Duke tracked body mass index (BMI) data on 3340 children who were part of the National Health and Nutritional Examination Survey (NHANES) in 2015 and 2016. The database is updated every 2 years.  

Obesity was defined by the Centers for Disease Control and Prevention as a BMI ≥ 85th percentile for age and sex. Class I obesity was defined as a BMI ≥ 95th percentile. Class II obesity was defined as a BMI > 120% of the 95th percentile or ≥ 35 kg/m2 (whichever was lower). Class III obesity was defined as a BMI ≥ 140% of the 95th percentile or ≥ 40 kg/m2 (whichever was lower).

Investigators tracked BMI data collected in 2-year cycles, starting with the 1999–2000 cycle and ending at the most recent 2015–2016 cycle.

"The prevalence of overweight and obesity increased with age," they report.

In the most recent NHANES cycle, 35.1% of the cohort was overweight or obese.  

In total, 18.5% of the cohort met the criteria for class I obesity, 6% met the criteria for class II obesity, and 1.9% met the criteria for class III obesity.

However, some age groups were more at risk than others for being overweight or obese.

For example, 41.5% of 16 to 19 year olds in the most recent NHANES cycle met the criteria for obesity and 4.5% of this age group met the criteria for class III obesity, the investigators point out.

Differences between rates of overweight and all classes of obesity in the most recent and previous cycle were not generally very marked.

One exception was a "sharp increase" in class I obesity among 2 to 5 year olds: 13.7% of these children met the criteria for class I obesity in the most recent cycle compared with 9.3% in the previous one.

Black and Hispanic Kids More Likely to Be Obese Than Whites

Regardless of age, both African American and Hispanic children were more likely to be overweight or obese (any class) than other ethnicities.

Indeed, African American and Hispanic girls and boys are two- to fourfold more likely to meet the criteria for class III obesity compared with white children, points out David Ludwig, MD, PhD, Boston Children's Hospital, Massachusetts, in an accompanying editorial.

In contrast, Asian American and white children had markedly lower rates of overweight or any class of obesity, the authors point out.

And in a related study, 2.1% of children from across the full NHANES survey interlude had severe obesity. The study, led by June M Tester, MD, MPH, from Children's Hospital Research Center, Oakland, California, and colleagues, was published online February 27 in Pediatrics.

In this select cohort, African American children were 70% more likely to have severe obesity than children of other ethnicities.

Hispanic children in the same NHANES cohort were also more than twice as likely to have severe obesity. They were also more likely to live in homes with lower educational exposure, that were single-parent households, and that were poor.

Being exposed to over 4 hours a day of screen time doubled the risk of severe obesity, and children who were not breastfed were 50% more likely to be obese, Tester and colleagues report.

Current Public Health Approach to Obesity Is Failing

"I think we've focused on making healthier foods more available, trying to encourage people to make healthier choices, and teaching healthcare providers how to communicate with families about weight and weight status in a sensitive way," said senior investigator of the Duke study, Sarah Armstrong, MD, Duke Health, Durham, North Carolina.

"But since we are seeing that these incremental changes really aren't having much of an impact, particularly among children who already have obesity and severe forms of obesity, we need to look at policies that are going to have a more disruptive impact on our society," she suggested.

Armstrong also had several practical suggestions to improve family health; for example, avoiding added sugar in beverages and food and incorporating vegetables into every meal, not just dinner.

"Even if your child is a picky eater and wants to eat the same vegetable every day, that is still a good choice," she observed.

Families also need to be active for an hour every day to help improve health, Armstrong added.  

Commenting further, Ludwig agrees that the current public health approach to the obesity epidemic has failed.

In fact, a recent growth trajectory predicts that most 2-year-old children alive today will be obese by the time they reach age 35 years (N Engl J Med 2017;377:2145-2153).

"The battle against childhood obesity faces many obstacles, most notably entrenched special interests and a 'business as usual' mindset," Ludwig writes.

"But with political will and collaboration across key sectors of society, we can hopefully, soon, begin to end this worsening epidemic," he concludes.

The study received no outside funding. The authors and editorialist have reported no relevant financial relationships.

Pediatrics. Published online February 26 (Abstract, Editorial) and February 27, 2018 (Abstract).

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