WASHINGTON — A new study based on the National Health and Nutrition Examination Survey (NHANES) appearing in the Jan. 20 issue of the Journal of the American Medical Association suggests the rate of obesity in the United States may be slowing. The findings come even as the prevalence of adults in the United States who are obese — 68% — remains high.
The study, which examined 5,555 adult men and women age 20 years and older from 2007-08, included an analysis of height and weight measurements, with overweight being defined as a body mass index of 25 to 29.9 and obesity defined as a B.M.I. of 30 or higher. The results were then compared with NHANES data for the 10-year period spanning 1999 to 2008.
The researchers found that in 2007-08, the prevalence of obesity was 33.8% overall, with prevalence 32.2% among men and 35.5% among women. Meanwhile, the prevalence of overweight and obesity combined was 68%, including 72.3% among men and 64.1% among women.
“For women, the prevalence of obesity showed no statistically significant changes over the 10-year period from 1999 through 2008,” the researchers noted. “For men, there was a significant linear trend over the same period, but estimates for the period 2003-04, 2005-06, and 2007-08 did not differ significantly from each other. These data suggest that the increases in the prevalence of obesity previously observed between 1976-80 and 1988-94 and between 1988-94 and 1999-2000 may not be continuing at a similar level over the period 1999-2008, particularly for women but possibly for men.”
Earlier data from 1988-94 showed that prevalence of obesity in U.S. adults increased approximately 8 percentage points since 1976-80 after being relatively stable over the period spanning 1960-80. Further analysis showed increases in obesity for both men and women and in all age groups during the 1999-2000 period.
In the most recent study, in most age groups, black adults exhibited the highest rates of obesity, followed by Mexican-Americans and whites.
The researchers pointed out that the prevention and treatment of overweight and obesity on a population-wide basis “are challenging.”
“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,” the researchers noted. “Enhanced efforts to provide environmental interventions may lead to improved health and to future decreases in the prevalence of obesity.”
In an accompanying editorial in the Jan. 20 issue of JAMA, J. Michael Gaziano, M.D., M.P.H., of the Massachusetts Veterans Research and Information Center; VA Boston Healthcare Systems; Brigham and Women’s Hospital, Boston, and contributing editor, JAMA, cautioned that while the study may provide some good news as far as trends, overweight and obesity remains a serious problem in the United States.
“But even if these trends can be maintained, 68% of U.S. adults are overweight or obese, and almost 32% of school-aged children and adolescents are at or above the 85th percentile of B.M.I. for age,” Mr. Gaziano said. “Given the risk of obesity-related major health problems, a massive public health campaign to raise awareness about the effects of overweight and obesity is necessary. 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.”