Obesity among children from lower earning families rose compared to their well-off counterparts, according to a study that suggests the U.S. weight epidemic may be another sign of a growing divide between rich and poor.
Using data from two national surveys of children ages 12 to 17 years old, researchers from Harvard University and Insead analyzed parents' level of education as shorthand for socioeconomic status, a measure of education, income and occupation. The study in Proceedings of the National Academy of Science found that children from less educated families exercised less and didn't cut their calories as much.
Though the prevalence of childhood obesity has leveled off since a decade ago, and children overall are consuming fewer calories and are more physically active, those gains aren't evenly distributed. Obesity among children whose parents are college-educated has dropped, while obesity among those in less- educated families continues to increase, the study said.
"We're finally beating obesity on the aggregate level, but when you look at the trends, it's very different for rich kids and poor kids," said Kaisa Snellman, one of the study's authors and a sociologist at Insead, an international business school. Lower education is usually linked to less income.
Children from parents with a high school education or less reduced their caloric intake to 2,105 in 2009 to 2010 from 2,271 calories in 1989 to 1991 to, according to the study. Those whose parents finished college or more dropped their intake to 2,150 from 2,487 in the same period.
The calorie difference may be because fresh fruits and vegetables are costly, making healthy alternatives less affordable for poor families. It may also be because 29.7 million people live in low-income areas, with a supermarket more than a mile away, researchers said.
In 2011, 91 percent of kids whose parents had some college education reported at least 20 minutes' exercise in the previous week, compared to 80 percent of those whose parents had high school education or less. The class gap in physical activity grew to 11 to 13 percentage points in 2011, compared to 2003, when the gap was only 3 to 7 percentage points.
"The neighborhoods are becoming more and more different, which might be one of the differences," Snellman said. "Can you go outside? Is it safe? Has the swing been stolen from your playground? Do you let your kid play in a park, unsupervised?"
Childhood obesity has more than doubled in children, and tripled in adolescents in the last 30 years, according to the Centers for Disease Control and Prevention. In 2010, more than a third of children were overweight or obese. Those who are obese are likely to remain that way, and are at risk for diseases such as type 2 diabetes, stroke, heart disease, some cancers, and arthritis.
There was no overall change in childhood obesity prevalence between 2003 to 2004 and 2009 to 2010, and some experts suggested that meant the rapid increases in obesity seen in the 1980s and 1990s are leveling off.
In order to change the trend for all groups, schools should increase the amount of physical education time and recess, Snellman said. Families might consider taking walks after dinner, dancing, or playing basketball together, she said. Health-care professionals should give advice about diet and exercise to parents whose children might be most at-risk.