Knowing your kid is overweight might make things worse

When parents think their child is overweight, that may put the kid at increased risk of packing on even more pounds, a new study suggests.

Previous research has found that parents are pretty bad at correctly guessing how much their children weigh. But the current study runs counter to the popular belief that kids might slim down when their mothers and fathers think they're too heavy.

"Generally, parents of healthy weight kids in this study assessed their weight status accurately," said co-author Dr. Eric Robinson of the University of Liverpool in the U.K.

"It may be that once a child is recognized as being overweight, parenting styles change in a way that promotes weight gain - i.e. serving larger meals or concerns over physical overexertion," Robinson added by email.

To see how parents' ideas about children's weight influenced future weight gain for kids, Robinson and co-author Angelina Sutin of Florida State University College of Medicine in Tallahassee examined data on 3,557 Australian children and their parents.

Children joined the study when they were 4 to 5 years old and researchers followed them until age 12 or 13.

At the start of the study, three quarters of kids were a normal weight for their height. About 20 percent were overweight or obese, while roughly 5 percent weighed too little.

Four out of five overweight children at age 4 or 5 were seen as normal weight by their parents, the researchers report in the journal Pediatrics.

For the roughly one in five overweight kids whose parents saw them as heavy, their odds of becoming even heavier relative to their height by the end of the study were much greater than if their parents didn't see them as overweight at the beginning.

One limitation of the study is that it relied only on weight and height measurements to assess whether children were at a healthy weight, the authors note. The researchers didn't look at another indicator of unhealthy weight known as adiposity, or excessive fat around the belly.

Researchers also lacked data on why parents thought children were overweight or what they did about it, the authors note.

"It's hard to say what is going on here without some additional information about the parents' weight status, socioeconomic status, and information about resources in the community such as access to healthy foods and safe spaces for physical activity," Davene Wright, a researcher at Seattle Children's Research Institute and the University of Washington who wasn't involved in the study, said by email.

Many factors, including poverty, consumption of sodas and sugar sweetened juices, sleep time and exercise can all influence childhood weight, noted Dr. Sandra Hassink, medical director of the American Academy of Pediatrics Institute for a Healthy Childhood Weight.

"Parents should be monitoring the growth of their children at every pediatric well visit," Hassink, who wasn't involved in the study, said by email.

Because parental perceptions of weight appear connected to future weight gain in the study, parents and other family caregivers may also need to take a close look at how they interact with overweight children to ensure they don't make the problem worse, said Jerica Berge, a researcher at the University of Minnesota who wasn't involved in the study.

"Parents who perceive their child as overweight may also engage in weight conversations with their child, such as telling their child that they are fat and need to lose weight," Berge said by email.

"Or, a parent may engage in food restriction behaviors if they perceive that their child is overweight," Berge added. "Both of these behaviors - weight talk and food restriction - have been shown in prior research to be associated with childhood obesity."