Why are the poor in the US growing obese?

New research from Harvard and INSEAD throws up an interesting find: overall adolescent obesity rates in the U.S. have plateaued after two decades of dangerous increase, but not for children of less-educated, poorer families. Instead, income and education increasingly influence children’s obesity

A new study conducted by researchers at INSEAD, the leading international business school, and Harvard University, uncovered a growing divide between rich and poor adolescent obesity rates. Whereas obesity among children from lower- earning families rose in the past decade, that of their well-off counterparts declined. The research findings of Kaisa Snellman (INSEAD Assistant Professor of Organisational Behavior), Carl B. Frederick (post-doctoral research fellow at Harvard Kennedy School of Government) and Robert D. Putnam (the Peter and Isabel Malkin Professor of Public Policy at Harvard Kennedy School of Government) appeared in their study, “Increasing Socioeconomic Disparities in Adolescent Obesity”, published in the Proceedings of the National Academy of Sciences.

Childhood obesity is one of the main public health concerns in the United States. The rate of obesity has more than doubled in children and tripled in adolescents over the last 30 years, according to the Centers for Disease Control and Prevention (CDC). 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.

Recent CDC reports suggest that child obesity rates have stabilised in the United States. But according to the INSEAD and Harvard researchers, the overall trend in youth obesity rates masks a significant and growing class gap between youth from upper and lower socioeconomic backgrounds.

[pullquote]The study finds that 1 in 5 kids from less educated, poor families report not having exercised or having played sports for at least 20 minutes sometime in the last seven days. By contrast, only 1 in 10 kids with college educated parents report such levels of physical inactivity[/pullquote]Using data from two national surveys of American children ages 12 to 17 years old, the researchers related obesity trends to parental income and education. Nationally, obesity among this group was static between 2003-2004 and 2009-2010. But during that period, obesity rates among adolescents whose parents have no more than a high-school education rose from about 20% to 25%. At the same time, the children of parents with a four-year college degree or more saw their obesity rates decline from 14% to about 7%. “It looks like we’re finally beating obesity on the aggregate level, but when you look at the trends more closely, they are very different for rich kids and poor kids. From the health policy perspective, this divergence is very alarming,” said Professor Snellman.

Looking deeper into the causes of this divide, the study found that the main contributor to the growing gap in obesity appears to be differences in the amount of physical activity, rather than caloric intake. Even children from less educated families consume fewer calories than they did a decade ago, but they are much less physically active today. By contrast, children from wealthy families have both reduced their caloric intake and become more physically active than before.

The study finds that 1 in 5 kids from less educated, poor families report not having exercised or having played sports for at least 20 minutes sometime in the last seven days. By contrast, only 1 in 10 kids with college educated parents report such levels of physical inactivity.

[pullquote]In poorer neighborhoods, the lack of community recreational centers, playgrounds, or sidewalks, along with concerns for safety when outdoors, can impede less-advantaged children from becoming physically active[/pullquote]These trends may derive from the fact that many children from lower socioeconomic groups live in environments that do not facilitate a physically active lifestyle. In poorer neighborhoods, the lack of community recreational centers, playgrounds, or sidewalks, along with concerns for safety when outdoors, can impede less-advantaged children from becoming physically active. However, this is not the full story: Participation in high school sports and clubs has increased among adolescents of higher socioeconomic status while decreasing for the others.

Authors of the study say that more vigorous government support and targeted programmes are needed to fight the epidemic, reduce disparities in physical activity, and prepare the nation to face the related future consequences. Research has shown that eating behaviors and lifestyles established in childhood often track into later life. If a boy is overweight at age 16, he will have an 80% likelihood of remaining obese as an adult. This likelihood is 92% for girls.