A new study suggests when it comes to childhood obesity, kids benefit from having a younger sibling.
And that link is surprisingly strong, according to an analysis of data from nearly 700 U.S. children.
Dr. Julie Lumeng, associate professor of pediatrics and public health at the University of Michigan’s Mott Children’s Hospital, was the study’s lead author.
Lumeng says the data show that when kids have a sibling two to four years younger, “they’re three times less likely to be obese by first grade, compared to children who didn’t have a sibling born into the family.”
Lumeng says the researchers found that strong link even when controlling for other factors that could affect weight. What they don’t know is why this effect exists.
Lumeng said it appears that something about “family rhythms and dynamics” change with the birth of a new baby – though whether it’s a change in feeding habits or increased activity that benefits the older child, researchers aren’t sure.
“There looks like there’s something going on here, but the mechanism we’re just not sure about,” Lumeng said. “But I think it deserves investigation.”
The findings appear in the April 2016 edition of the journal Pediatrics.
