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Adult Obesity May Have Origins Way Back In Kindergarten

Playing outside can help kids — and their parents — maintain a healthy weight.
Playing outside can help kids — and their parents — maintain a healthy weight.

A lot of parents like to think their kids will simply outgrow baby fat. But the risk of becoming a severely overweight adult can actually start as early as kindergarten, research suggests.

"As parents, as a society, as clinicians, we need to think about a healthy weight really early on," says Solveig Cunningham, who led the study. But that doesn't mean putting young children on calorie-restricted diets.

In hopes of figuring out when in life the warning signs of obesity emerge, Cunningham and her colleagues studied more than 7,000 children from the time they started kindergarten through middle school.

"Kids who started off kindergarten overweight actually had about four times [the risk] of becoming obese by eighth grade, compared with normal-weight kindergartners," says Cunningham, an assistant professor in the department of global health at Emory University. And nearly half of the obese eighth-graders , she says, had been overweight kindergartners.

The findings, published Wednesday in The New England Journal of Medicine, suggest the "risks for obesity are in part set fairly early in life" — maybe as early as during the mother's pregnancy, Cunningham says. A third of the children who ended up being obese by eighth grade were also on the large side at birth.

Pregnancy and the first few years of a child's life are clearly influential, according to Dr. David Ludwig, a specialist in childhood obesity at Boston Children's Hospital. "Maternal diet, maternal weight gain and the infant's diet during the first few years may have an outsized influence on long-term risk for obesity and related diseases."

That means that women need to be careful not to gain too much weight while they're pregnant, Ludwig says, as well as try to make sure their young children don't sit around too much, watching TV and playing video games. Helping kids get exercise is important, he says, as is helping them develop healthful eating habits.

Teach children to go easy on the refined carbohydrates from the start, Ludwig advises — "the sugary beverages, too much fruit juice and all of the processed, packaged snack foods."

Still, some experts worry that studies like this could lead parents to overreact at any sign that their babies or toddlers are getting a little chubby. "Putting [young children] on a calorie-restricted diet can stunt their growth in height," says Joanne Ikeda, a nutritionist at the University of California, Berkeley. That's definitely not the answer, she and pediatricians agree.

"What you want to do," Ikeda says, "is help them have healthier lifestyle habits and they will grow into their weight."

Children are already suffering from a kind of societal hysteria about childhood weight, according to Linda Bacon, a physiologist who studies weight regulation and nutrition at the University of California, Davis.

"What this is going to do to kids is ... cause more bullying and teasing of the larger kids," she says. "It's going to cause them to feel bad about their bodies. It's going to make the thinner kids really scared of getting fatter. There is so much public and media hysteria about the epidemic of childhood obesity already."

The researchers behind this study don't advocate putting young children on diets or making them feel bad about their weight. They say they just hope their work will help discourage the bad habits that are in large part driving the childhood obesity epidemic.

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Rob Stein is a correspondent and senior editor on NPR's science desk.