CHAPEL HILL, N.C., Oct. 23 (UPI) -- Researchers say childhood obesity varies among countries of differing levels of socioeconomic development, with industrialized nations, such as the United States, experiencing higher rates than developing countries, such as China.
"We studied childhood obesity levels in Russia, China and the United States and found that different (social and economic) groups are at different risks, and the relationship between obesity and socioeconomic status varies across countries," said Youfa Wang, a researcher at the University of North Carolina's Population Center and School of Public Health in Chapel Hill.
In the United States, obese and overweight children made up 11 percent and 14 percent of the overall child population, respectively. In Russia, 6 percent of children were obese and 10 percent were overweight. In China the rates were almost 4 percent and 3 percent, respectively.
The study defined overweight and obese using the World Health Organization's Body Mass Index, which is calculated by dividing weight by height. In this case, BMIs in the 85th and 95th percentiles defined "overweight" and "obese."
Levels of social and economic standing had different effects depending on the country. Subjects with higher social positions were more likely to be obese in China and Russia, but U.S. children of lower status were more often categorized as overweight. In China, urban children tend to be larger as opposed to rural youngsters in Russia.
Wang initiated his review after the WHO acknowledged a need to study childhood obesity across countries using a common standard. Wang's paper noted previous studies in adults show obesity and socioeconomic factors "are correlated but results (have been) inconsistent for children."
He used comparable data for children ages 6 to 18 from health surveys conducted in America between 1988 and 1994. Data in China was taken in 1993 and in 1992 for Russians.
Wang chose the three nations partly because they are the world's most populous, accounting for nearly a quarter of the world's population, and they represent three distinct levels of economic development.
Wang said families in developing countries often experience spikes in personal income, resulting in newfound access to energy-dense foods, such as refined grains and meat. He wrote countries should counter swift economic changes by publicizing the risks of obesity as well as ways to maintain healthy lifestyles.
"The lack of adequate nutrition and health-related knowledge to cope with the rapid shifts in people's environment -- food availability, lifestyles, etc -- and the lack of effective channels to deliver such knowledge to the public, are challenges needing to be addressed in these societies," his study reports.
Meanwhile, Wang, who recently joined the University of Illinois at Chicago as assistant professor of human nutrition, said childhood undernutrition is a serious problem that should be confronted at the same time as obesity issues.
The paper does not "seem to bring surprises" other than the prevalence of obesity among affluent Chinese, said Michael Goran of the Institute for Preventive Research at the University of Southern California, Los Angeles. "That certainly has to do with the more ready access to Westernized diets and I would think increased likelihood of more sedentary lifestyle behaviors."
Goran said the biggest medical risk associated with childhood obesity is diabetes.
"A lot of people think diabetes is an adult disease," he said. "But now children who are overweight are at increased risk. There is also the risk of long-term diseases like cardiovascular disease and other social problems such as stigmatization."
(By Kelly Hearn in Washington)