December 20, 2014

New USC-led study finds “very telling” lack of research on childhood obesity

Despite popular belief that unhealthy diets and sedentary behavior are big reasons for the increase of childhood obesity the past decade, a new review by three South Carolina universities said there is a startling lack of conclusive research to support those beliefs.

A new review by the University of South Carolina’s Arnold School of Medicine, Clemson, the Medical University of South Carolina, and others found that long-term prospective studies have only been able to return “mixed evidence” in those factors.

The review concluded that much more long-term research is needed to better understand the causes of childhood obesity.

“Part of what was very telling for us is that the things which get the most attention in the media or among conversations actually had the least convincing evidence in favor of them,” Clemson sociology professor Ellen Granberg told South Carolina Radio Network.

The team examined 61 long-term studies that met their criteria of a “prospective” study into childhood obesity. These were long-term studies that followed the same group of kids over time and tried to identify whether a certain factor could be linked to obesity in its subjects.

The researchers found that there was evidence to link genetic factors and low physical activity with excessive fatness in children. However, the evidence was mixed on sedentary behavior, dietary intake, physiological biomarkers, family factors and the community physical activity environment. And studies were practically non-existent on cognitive factors, peer factors, school nutrition, physical activity environments, and the community nutrition environment.

For those who were wondering, yes, there is a difference between “low-physical activity” and “sedentary behavior.”

“There’s pretty good evidence that being physically active will reduce your likelihood of becoming overweight over the course of childhood,” Granberg said. “But there is really only very mixed evidence that being sedentary increased the probability.”

“Obesity is a multifaceted problem for youth and adults,” USC exercise physiologist Russ Pate, who led the study, said in a statement. “Public health interventions aimed at prevention should be based on a comprehensive understanding of the behavioral, environmental, physiological and cultural factors associated with excessive fatness in childhood and adolescents.”

The findings were published the Obesity Reviews journal.

Granberg emphasized that the research did not conclude there was no link between diet or lifestyle in childhood obesity— just that research had not established it yet.

“The fact that we found limited evidence doesn’t mean that it’s not an important cause,” she said. “Just that it’s an understudied cause.”

“Given that childhood obesity is a worldwide public health concern, the field can benefit from large-scale, long-term prospective studies that use state-of-the-art measures in a diverse sample of children and adolescents,” the study concludes.

Researchers from the universities of Iowa, Michigan, and the Pennington Biomedical Center at LSU were also involved in the study.