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 January 20 issue of JAMA. The study is being published early online because of its public health importance.
"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 United States 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 United States since 1976-1980, after being relatively stable over the period 1960-1980. Analyses of data from 1999-2000 showed further increases in obesity for both men and women and in all age groups," the authors write.
Katherine M. Flegal, Ph.D., of the Centers for Disease Control and Prevention, 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 25.0 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, prevalence was 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 33.0 percent among non-Hispanic white women to 49.6 percent among non-Hispanic black women. The prevalence of overweight and obesity combined was 68.0 percent overall, 72.3 percent among men, and 64.1 percent among women.
"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. 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 authors write.
"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 write. "Enhanced efforts to provide environmental interventions may lead to improved health and to future decreases in the prevalence of obesity."