Morbid obesity affects more than 1 percent of American teens

The prevalence of morbid obesity has grown dramatically among American adolescents and children, according to an analysis of data collected by the most recent national health survey.

On the basis of data from the National Health and Nutrition Examination Survey (NHANES) 1999-2004, about 418,000 adolescents aged 12-19 had a body mass index (BMI) of at least 40kg/m2, reported in a poster at a conference on cardiovascular disease epidemiology and prevention sponsored by the American Heart Association. This represented about 1.3% of the adolescent population in the United States in 2000. Included in this group were 71,000 adolescents with a BMI of 50kg/m2 or greater.

With another definition of severe obesity, 3.8% of American children aged 2-19 had a BMI at or above the 99th percentile for their age in the NHANES 1999-2004 sample. This prevalence translates into about 2.7 million children.

By convention, children younger than 12 are defined as severely obese if their BMI meets or exceeds the 99th percentile for age because the usual definition of morbid obesity — 40kg/m2 or greater — is not relevant for younger children. The spread of obesity is reflected by the fact that BMI levels that, several years ago, were only reached by the heaviest 1% of children in each age group have now been reached by 3.8% on average.

More specifically, the prevalence of BMIs at or above the 99th percentile between the prior NHANES survey in 1988-1994 and the 1999-2004 survey said by a pediatrician at the University of Rochester (New York).

The high prevalence and rapid increase of this group of children and adolescents portend a large burden to the health care system, the researchers said in their poster. The progress that we’ve made in preventing and treating cardiovascular disease in adults will be reversed by childhood and teenage obesity.

The jump in obesity rates between the current survey and the prior one was sharpest among Mexican Americans, African Americans, and “other” racial and ethnic groups. There was essentially no change in the rate among children classified as white. In NHANES 1999-2004, the highest prevalence of a BMI of 40 or greater was among African Americans, affecting 3.4% of this subgroup.

NHANES 1999-2004 collected data on 12,384 American children who were selected to create a sample that represented the American population at that time.