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NEW YORK (Reuters Health) - While the extent of obesity among kids overall seems to have peaked, it's still climbing among African American and Native American girls, new research from California shows.
And the biggest obesity increases over the past decade have occurred among the heaviest youths, no matter what their gender or ethnicity, Dr. Kristine Madsen of the University of California, San Francisco, and her colleagues found. "Our heaviest kids are getting heavier," Madsen said in an interview.
Recent national data suggest that the percentage of children who are obese has plateaued, "representing the first sign of abatement in the pediatric obesity epidemic," Madsen and her team note in the September issue of Pediatrics. But that same data, covering 1999 through 2008, also show Hispanic and black children were more likely to be obese than non-Hispanic whites.
To better understand trends in childhood obesity by race, Madsen and her colleagues looked at data on nearly 8.3 million California fifth-, seventh- and ninth-graders who had undergone body mass index (BMI) screening between 2001 and 2008.
BMI is a measure of weight in relation to height used to gauge obesity. In children, BMI is used somewhat differently than it is in adults; a child is considered to be obese if his or her weight in relation to height and age is in the 95th percentile, meaning the child is heavier than 95 percent of peers of the same age and height. A child is considered to be severely obese if his BMI is in the 99th percentile, or he weighs more than 99 percent of peers of the same height.
For example, Madsen explained, a 14-year-old boy 5 feet 4.5 inches tall (the typical height for his age) would be considered obese if he weighed at least 154 pounds; he would be severely obese if he weighed 198 pounds or more.
When the researchers used the 95th percentile cutoff in their analysis, they found that obesity prevalence - the proportion of obese kids in a larger group -- declined among most boys and for white girls after 2005. Obesity prevalence stayed the same after 2005 for Hispanic girls, but it continued to climb for African American and Native American girls. "We haven't even found their peak," Madsen said.
And the prevalence of severe obesity only declined among white and Asian boys; for everyone else, it stayed the same or increased. In 2008, the researchers found, about 5 percent of Native American and African-American girls were severely obese, compared to just over 1 percent of non-Hispanic white girls.
While it's good news that obesity is declining among some groups of children, the researcher said, "the bad news is that decline is limited to only certain groups, which means that the disparities are increasing."
The researcher said her findings are likely to be generalizable to the US as a whole, given that the prevalence numbers she and her colleagues found were very similar to those seen by other researchers.
For example, 19.8 percent of children in the total California study population were in the "obese" 95th percentile in 2008 and 3.6 percent of them were severely obese. A national survey of children aged 6 to 19 in 2007-2008 found 18.7 percent of kids to be obese.
There are interventions known to be effective in fighting child obesity, Madsen noted; the trick is to make sure these efforts don't make disparities even worse by leaving out the people who need them the most. School-based programs, including increasing physical education time and improving "nutritional environment," have the best chance of helping all children, she added.
Other approaches that could have great benefit, the researcher added, would be eliminating the advertising of unhealthy food to children, and putting a tax on sugary soft drinks. "There are many pediatricians that would really support a soda tax," she said.
SOURCE: link.reuters.com/mex36n Pediatrics, September 2010. (Online, August 16, 2010).