Researchers have noticed for years that adolescents who came from higher-income families with more education tended to be less obese in the United States than comparable children from families with less money and less formal education.
One problem with that observation was that it suggested obesity and overweight would be difficult to curtail because such characteristics were so slow and hard to change, scientists say.
A new University of North Carolina at Chapel Hill study shows that is not uniformly true for both sexes and various ethnic-racial groups.
“We found that overweight was lower among white girls from higher-income, better-educated families than among other white girls, but overweight did not similarly decrease with high income and education among black girls,” said Dr. Penny Gordon-Larsen, assistant professor of nutrition at the UNC School of Public Health and a fellow at the Carolina Population Center. “We can’t say for certain why that’s true, but it’s good news in the sense that it shows that focusing on other things such as social and environmental factors might allow us to prevent or reduce overweight better among some groups of adolescents.
“Obesity is a huge problem for all groups of adolescents, but it’s particularly a problem among minority populations,” she said. “Among the health problems it creates or makes worse are diabetes, cardiovascular disease and high blood pressure.”
Gordon-Larsen is lead author of a report on the study appearing in the January issue of Obesity Research, the top obesity journal. Her co-authors are Drs. Linda Adair and Barry M. Popkin, associate professor and professor, respectively, of nutrition and fellows at the Carolina Population Center.
The research team set out to investigate why obesity is higher in minority groups. They analyzed nationally representative data collected from 13,113 U.S. adolescents enrolled in the UNC-based National Longitudinal Study of Adolescent Health (Add Health).
Gordon-Larsen and colleagues used statistical techniques to examine the relationship of family income and parents’ education to the prevalence of overweight in various racial and ethnic groups. They also looked at what happened when they mathematically equalized income and education among all the adolescents.
“When we equalized them statistically and made everyone have an income of $80,000 or more, we found that overweight was considerably low for white, Hispanic and Asian girls but conversely, remained high for black girls,” she said. “Thus black-white disparity in overweight was actually highest at the highest income and education levels. The pattern was not as extreme among males, with higher overweight among Hispanic and black males versus white and Asian males, even at the more elevated income and education levels.”
The conclusion they drew was that since obesity differences are not just reflections of socioeconomic differences — as often believed — broad public health efforts may indeed help produce solutions to the national obesity problem among adolescents.
“People need to look at environmental, contextual and community factors and culture, which are concrete things that we can actually manipulate and change to decrease overweight,” Gordon-Larsen said. “If we can create a culture — especially in minority populations that are underserved in terms of health care — where people value being physically active, where they understand that they need to build physical activity into their daily lives and get out and do 30 minutes or more a day of moderate to vigorous physical activity for their health, then we can make a difference.”
Examples of environmental factors affecting obesity and amenable to change include building “walkable” communities, decreasing crime rates and increasing recreational opportunities that promote physical activity, she said.
The new analysis was supported in part by grants from the National Institute of Child Health and Human Development, which has been the major long-term supporter of the Add Health study. That larger, continuing study has involved collecting and analyzing responses from tens of thousands of U.S. adolescents surveyed about their lives, health and habits.