Two investigations being published by JAMA reveal that the prevalence of obesity in the United States has not changed considerably. Approximately 1 in 3 adults and 1 in 6 children and adolescents are obese, according to data from 2009-2010. The data also revealed that the prevalence of obesity in certain demographics has increased.

In order to determine obesity rates in the U.S., Drs. Katherine M. Flegal, Cynthia L. Ogden and colleagues with the Centers for Disease Control and Prevention, Hyattsville, Md., examined data from the 2009-2010 National Health and Nutrition Examination Survey (NHANES). Rates of obesity among adults were compared with data from 1999-2008. Obesity was defined as a body mass index (BMI) of 30 or greater. The Survey includes the heights and weights of 22,847 adult individuals from a nationally representative sample of the U.S. population in 1999-2008 and 5,926 adult individuals in 2009-2010.

After adjusting for age, the average BMI was 28.7 for men and women in 2009-2010. Overall, the age-adjusted obesity prevalence was 35.7%. The prevalence of obesity among men was 35.5%, while the prevalence of obesity within race/ethnicity groups ranges from 38.8% among non-Hispanic black men to 36.2% among non-Hispanic white men. The researchers found that between 1999/2000 and 2009/2010 there was a considerable increase in obesity for men.

The prevalence of obesity among women was 35.8%, while the prevalence within race/ethnicity groups ranged from 58.5% among non-Hispanic black women to 32.2% among non-Hispanic white women. Overall the team found no significant increase in the prevalence of obesity among women over the period from 1999 through 2010, although they discovered that for non-Hispanic black women and Mexican American women increases were statistically considerable.

For both genders, 2009 to 2010 did not differ considerably from the past 6 years (2003-2008).

Overall, the age-adjusted prevalence of overweight and obesity combined (BMI 25+) was 68.8%, 63.7% among women, and 73.9% among men.

The researchers explain:

“Obesity prevalence shows little change over the past 12 years, although the data are consistent with the possibility of slight increases.”

In order to determine the prevalence of obesity among children and teens in the U.S. (birth to 19 years of age), the researchers examined NHANES data from 2009-2010 which included a representative sample (n=4,111 [1,376 non-Hispanic white, 792 non-Hispanic black, and 1,660 Hispanic]) with measured heights and weights. Among the measures examined, were the prevalence of high weight-for-recumbent length (95th percentile or greater on the growth charts) among children from birth to 2 years old as well as obesity (BMI 95th percentile or greater of the BMI-for-age growth charts) among those aged 2 to 19 years. In addition, there were examinations of obesity trends by gender and race/ethnicity, as well as BMI within gender-specific age groups every two years from 1999 to 2010.

The team discovered that 16.9% of the children and adolescents examined aged 2 to 19 years were obese in 2009-2010, and 31.8% were overweight or obese. The prevalence of obesity among females was considerably lower (15.0%) than among males (18.6%). Between 2007-2008 and 2009-2010, the researchers found no difference in obesity prevalence among both genders, although the prevalence increased significantly between 1999-2000 and 2009-2010 in male children and teens but not females.

The researchers explain:

“Significant differences in obesity prevalence by race/ethnicity were found. In 2009-2010, 21.2 percent of Hispanic children and adolescent and 24.3 percent on non-Hispanic black children and adolescent were obese compared with 14.0 percent of non-Hispanic white children and adolescents.”

In 2009-2010 the team found that the prevalence of high weight-for-recumbent length among children from birth to 2 years was 9.7% and did not change between 1999-2000 and 2009-2010. When the researchers examined these two time periods together they discovered that Mexican Americans are considerably more likely to have high weight-for-recumbent length than non-Hispanic whites.

Furthermore, they discovered that among males aged 12 to 19, there was a considerable increase in BMI, but not among females or any other age group.

The researchers explain:

“Many efforts both at the national level and at state and local levels focus on reducing childhood obesity. Yet results from NHANES indicate that the prevalence of childhood obesity in the United States remains unchanged at approximately 17 percent; although increases in obesity prevalence may be occurring among males.”

Written by Grace Rattue