US Obesity Prevalence High but Stable in Recent Years

Miriam E. Tucker

February 25, 2014

The high overall obesity prevalence in the United States hasn't budged in recent years, a new study from the Centers for Disease Control and Prevention (CDC) finds.

"Overall, there have been no significant changes in obesity prevalence in youth or adults between 2003–2004 and 2011–2012. Obesity prevalence remains high, and thus it is important to continue surveillance," Cynthia L. Ogden, PhD from the CDC's National Center for Health Statistics, Hyattsville, Maryland, and colleagues write in the February 26 issue of the Journal of the American Medical Association.

"Obesity, once present, is tenacious," Matthew W. Gillman, MD, director of the Obesity Prevention Program at Harvard Pilgrim Health Care Institute, Boston, Massachusetts, told Medscape Medical News.

"Primary care is an important setting, but only one of many, for prevention and treatment of obesity. Approaches that involve entire communities, as well as state and national policies, appear to be required," added Dr. Gillman, who was not associated with the study.

The new data, from the National Health and Nutrition Examination Survey (NHANES), also show that although overall obesity rates didn't change between the 2 study periods, obesity rose significantly among women aged 60 and older and dropped significantly among children aged 2 to 5 years.

"I was surprised to see the decrease in obesity among young children 2 to 5 years of age. This is the first time we have seen a decrease in obesity in any group since we have been tracking it nationally," Dr. Ogden told Medscape Medical News.

But Dr. Gillman pointed out that other recent studies have documented this decline in young children. These include his own data from Massachusetts, demonstrating a significant fall in obesity rates among those less than 6 years of age during 2004–2008 and a report from the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), showing a drop among 2- to 4-year-olds from 2008 to 2011.

Referring to the 2- to 5-year age group, Dr. Gillman said, "It's great to see this decline after so many years of increasing obesity rates."

Obesity by Numbers

In NHANES during 2011–2012, weights and heights (or recumbent length for infants) were measured in a total of 9120 individuals, including 5181 adults aged 20 and older, 3355 children and adolescents, and 584 infants and toddlers less than 2 years of age.

Among those under 2, the proportion with excessive weight for recumbent height — used as a proxy for obesity in that age group — was 8.1% [based on the 95th or greater percentile on the CDC's sex-specific growth charts for the year 2000]. That represents a nonsignificant drop of 1.4 percentage points since 2003–2004.

For children and adolescents aged 2 to 19 years, the proportion with body mass indexes (BMIs) at or above the 95th percentile was 16.9%. That figure is also a nonsignificant 0.2 percentage points less than the 2003–2004 prevalence.

The percentage of adolescents aged 12 to 19 years who met the adult definition of obesity (BMI 30 kg/m2 or above) was 13.9% in 2011–2012, which again represented no significant change from 2003–2004, Dr. Ogden and colleagues note.

In adults age 20 years and older, the proportion with BMI of 30 kg/m2 or greater was 34.9%, a nonsignificant increase of 2.8 percentage points from 2003–2004.

When the age groups were broken down further, there were 2 significant changes from 2003–2004 to 2011–2012: obesity had dropped by 5.5 percentage points among the 2- to 5-year-olds (from 13.9% to 8.4%; P = .03) and had risen among the 60-plus group by 4.4 percentage points to 35.4% (P = .004).

Rise in Obesity in Women

The authors also found some significant differences in current obesity levels by sex and race. For example, while there was no difference in obesity prevalence between boys and girls, non-Hispanic Asian youth were significantly less obese than those of other races (P < .001).

Dr. Ogden and colleagues note, however, that evidence suggests that Asians may have more body fat than whites at lower BMIs, and that a World Health Organization (WHO) expert committee has recommended lower cutoffs for Asians for consideration of "public-health action."

Among adults, the prevalence of grade 3 obesity (BMI 40 or greater) was higher in women than men (8.3% vs 4.4%, P = .004) and was highest among those aged 40 to 59 compared with those older and younger (P = .03) and among non-Hispanic black adults compared with other races (P < .001).

And among women aged 60 and over, the obesity prevalence rose from 31.5% in 2003–2004 to 38.1% in 2011–2012 (P = .006).

Interpreting the findings

The study wasn't designed to elucidate the reasons for the obesity trends, Dr. Ogden told Medscape Medical News.

However, Dr. Gillman offered an "interesting hypothesis" for the pediatric obesity decline: "Because birth weight is directly associated with later BMI, whatever is causing the recent decline in birth weight in the US and other countries could underlie a reduction in relative weight in early childhood," he said.

The next obesity update is expected in 2 years, when data from 2013–1024 become available, Dr. Ogden said.

Dr. Ogden has reported no relevant financial relationships. Dr. Gillman has received travel expenses and honoraria from Danone and the Nestle Nutrition Institute.

JAMA. Published online February 25, 2014.

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