Despite the widely held belief that adolescents who come from higher-income families tend to be less obese than comparable children from families with less income, a new study suggests that this may not be uniformly true for both sexes and various ethnic-racial groups.
Research at the University of North Carolina in the US shows that obesity is a particular problem among minority populations.
"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, lead author of the study and assistant professor of nutrition at the UNC School of Public Health. "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. "
"Among the health problems it creates or makes worse are diabetes, cardiovascular disease and high blood pressure," she added.
The research team set out to investigate why obesity is higher in minority groups. They analysed nationally representative data collected from 13,113 US 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 equalised income and education among all the adolescents.
"When we equalised 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 researchers drew the conclusion 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," said Gordon-Larsen.
Full findings are published in the January issue of Obesity Research.