JAMA: U.S. obesity high, with some signs of stabilization

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The prevalence of adults in the U.S. who are obese is still high, with about one-third of adults obese in 2007-2008, although new data suggest that the rate of increase for obesity in the U.S. in recent decades may be slowing, according to a study appearing in the Jan. 20 issue of the Journal of the American Medical Association.

The National Health and Nutrition Examination Survey (NHANES), a nationally representative sample of the U.S. population, provides the opportunity to track trends in the prevalence of obesity in the U.S. by collecting data on height and weight measurements.

“Data from 1988-1994 showed that the prevalence of obesity in adults had increased by approximately 8 percentage points in the U.S. since 1976-1980, after being relatively stable over the period 1960-1980,” the authors wrote. “Analyses of data from 1999-2000 showed further increases in obesity for both men and women and in all age groups.”

Katherine M. Flegal, PhD, of the Centers for Disease Control and Prevention in Hyattsville, Md., and colleagues examined the latest NHANES data from 2007-2008 regarding trends in obesity and compared the results with data for 1999 through 2006.

The study included an analysis of height and weight measurements from 5,555 adult men and women age 20 years or older. Overweight was defined as a body mass index (BMI) of 25 to 29.9. Obesity was defined as a BMI of 30.0 or higher.

The researchers found that in 2007-2008, the prevalence of obesity was 33.8 percent overall. Among men, obesity was present 32.2 percent overall and within racial and ethnic groups, ranged from 31.9 percent among non-Hispanic white men to 37.3 percent among non-Hispanic black men. For women, the prevalence was 35.5 percent overall, and ranged from 33 percent among non-Hispanic white women to 49.6 percent among non-Hispanic black women.

The prevalence of overweight and obesity combined was 68 percent overall, 72.3 percent among men, and 64.1 percent among women, the authors reported.

“For women, the prevalence of obesity showed no statistically significant changes over the 10-year period from 1999 through 2008. For men, there was a significant linear trend over the same period, but estimates for the period 2003-2004, 2005-2006, and 2007-2008 did not differ significantly from each other,” Flegal and colleagues commented.

They wrote that these data suggest that the “increases in the prevalence of obesity previously observed between 1976-1980 and 1988-1994 and between 1988-1994 and 1999-2000 may not be continuing at a similar level over the period 1999-2008, particularly for women but possibly for men.”

“The prevention and treatment of overweight and obesity on a population-wide basis are challenging,” the authors concluded. “Population-based strategies that improve social and physical environmental contexts for healthful eating and physical activity are complementary to clinical preventive strategies and to treatment programs for those who are already obese.”

In an accompanying editorial, J. Michael Gaziano, MD, of the Massachusetts Veterans Research and Information Center in Boston, said that while this analysis on the prevalence of overweight and obesity may offer some good news as far as trends, it is still a “serious problem in the U.S.”

“But even if these trends can be maintained, 68 percent of U.S. adults are overweight or obese, and almost 32 percent of school-aged U.S. children and adolescents are at or above the 85th percentile of BMI for age,” Gaziano wrote.

He suggested a massive public health campaign to raise awareness about the effects of being overweight or obese is “necessary” because such campaigns have been successful in communicating the dangers of smoking, hypertension, and dyslipidemia; educating physicians, other clinicians, and the public has yielded significant returns.

“Major research initiatives are needed to identify better management and treatment options. The longer the delay in taking aggressive action, the higher the likelihood that the significant progress achieved in decreasing chronic disease rates during the last 40 years will be negated, possibly even with a decrease in life expectancy,” Gaziano wrote.

The journal noted that the study was published early online because of its “public health importance.”