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Member Research & Reports

Member Research & Reports

Michigan Study Examines Influence of Siblings on Childhood Obesity Development

As a pediatrician, SPH professor in the nutritional sciences Dr. Julie Lumeng, has seen plenty of finger-pointing when it comes to childhood obesity. Her new study attempts to shed light on one aspect of the etiology of the issue.

Julie Lumeng
[Photo: Dr. Julie Lumeng]

“People automatically assume you’re an inept parent if your child is obese, so there’s a lot of mother blaming in today’s society,” said Dr. Lumeng, also a professor of pediatrics and communicable diseases. “But when it comes to eating, children are much more likely to model their eating behavior after other kids — not adults.”

That realization inspired Dr. Lumeng and her colleagues to watch hundreds of videotapes that show families eating dinner together. Researchers coded interactions between siblings at the dinner table, which led them to one simple question: Does the addition of a new brother or sister alter the older sibling’s risk of obesity moving forward?

About 700 children participated in the study, which included assessments to gauge their body mass index over time. Their findings show that becoming a big brother or big sister before first grade may lower a child’s risk of becoming obese.

“The effect seems to be strongest when the sibling is about two years apart,” said Dr. Lumeng, who serves as associate director of the Momentum Center and also has ties to the Center for Human Growth and Development.

Children with younger siblings are more prone to engage in active play, thus reducing their risk of obesity, which Dr. Lumeng believes could contribute to their findings. Parents also may change the way they feed their child once a new sibling is born, which can significantly alter their long-term eating habits.

“The implication of this study is certainly not to go out and have more babies in an effort to prevent their older siblings from being obese later in life,” she said. “Instead, parents should reflect on how their parenting habits might change after having a second child, and whether they can recreate those changes. As we continue to look more closely at the connection between siblings and weight, we can help create new strategies for helping children grow up healthy.”

This study is one of multiple studies related to childhood obesity that are discussed in UM’s Research Newsletter; this issue is titled “Tipping the Scales.”

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