Increase in Obesity Among American Young is Leveling Off The seemingly inexorable increase in the percentage of obese children in the U.S. appears to have flattened out, according to a new study, published in the current Journal of the American Medical Association. According to the authors, it is not clear whether the change is the beginning of a new trend or a statistical artifact. According to the study by researchers at the National Center for Health Statistics of the Centers for Disease Control and Prevention (CDC), the proportion of 2-to-19 year olds who are overweight has stopped rising for the first time since the 1980s. The percentage of high BMI for age among children and adolescents showed no significant changes between 2003-2004 and 2005-2006, according to Cynthia L Ogden and her colleagues. Even if the leveling off continues, the prevalence of overweight among American children remains high, and that could mean years of serious health problems as they grow older. The study included weight and height measurements from a sample of 8,165 children collected as part of the 2003-2004 and 2005-2006 National Health and Nutrition Examination Surveys. The measurements were converted to a body weight index (BMI), the weight in kilograms divided by height in meters squared, the common metric for categorizing weight. Obesity is defined as having a BMI at or above the 95th percentile on growth charts. In the 1960s and 1970s, only 5 percent of children in the United States were obese. The figure now is 15.5 percent. Overweight is defined as the 85th percentile. Currently, 31.9 percent of American children qualify as either obese or overweight, and 11.3 percent were above the 97th percentile, characterized as very obese. The good news is that there is no statistically significant change in those figures since 1999, which leads the researchers to conclude that the plateau may be real and not a temporary pause. Additionally, the flat results cut across gender, race and ethnic lines, although older non-whites continued to have higher rates of obesity than did whites. The research did not explore why the increase has halted. Words of caution were provided in a JAMA editorial by Cara B. Ebbeling and David S. Ludwig. They pointed out that BMI may not necessarily be the best measure for characterizing weight issues or in predicting future health problems. "Historical cohort studies document an association between childhood BMI and chronic disease in childhood,” they wrote, “but optimal levels of BMI for long-term health are not known." "It is too early to know whether these data reflect a true plateau or a statistical aberration in an inexorable epidemic, and pre-existing racial/ethnic disparities show no sign of abating," they wrote. "On one point there is no uncertainty: without substantial declines in prevalence, the public health toll of childhood obesity will continue to mount, because it can take many years for an obese child to develop life-threatening complications." The journal article may be found at http://jama.ama-assn.org/cgi/content/full/299/20/2401. The editorial may be found at: http://jama.ama-assn.org/cgi/content/full/299/20/2442. |
