Those efforts to fight obesity in schools? Think younger. A new study finds that much of a child’s “weight fate” is set by age 5, and that nearly half of kids who became obese by the eighth grade were already overweight when they started kindergarten.
The prevalence of weight problems has long been known – about a third of U.S. kids are overweight or obese. But surprisingly little is known about which kids will develop obesity, and at what age.
Researchers think there may be a window of opportunity to prevent it, and “we keep pushing our critical window earlier and earlier,” said Solveig Cunningham, a scientist at Emory University. “A lot of the risk of obesity seems to be set, to some extent, really early in life.”
She led the new study, which was published in this week’s New England Journal of Medicine and paid for by the federal government.
It tracked a nationwide sample of more than 7,700 children through grade school. When they started kindergarten, 12 percent were obese and 15 percent were overweight. By eighth grade, 21 percent were obese and 17 percent were overweight.
Besides how common obesity was at various ages, researchers focused on the 6,807 children who were not obese when the study started, at kindergarten entry. Here are some things they found:
WHO BECAME OBESE: Between ages 5 and 14, nearly 12 percent of children developed obesity – 10 percent of girls and nearly 14 percent of boys.
Nearly half of kids who started kindergarten overweight became obese teens. Overweight 5-year-olds were four times as likely as normal-weight children to become obese (32 percent versus 8 percent).
GRADE LEVELS: Most of the shift occurred in the younger grades. During the kindergarten year, about 5 percent of kids who had not been obese at the start became that way by the end. The greatest increase in the prevalence of obesity was between first and third grades; it changed little from ages 11 to 14.
INCOME: Obesity was least common among children from the wealthiest families and most prevalent among kids in the next-to-lowest income category. The highest rate of children developing obesity during the study years was among middle-income families.
BIRTH WEIGHT: At all ages, obesity was more common among children who weighed a lot at birth – roughly 9 pounds or more. About 36 percent of kids who became obese during grade school had been large at birth.
The work also shows the need for parents, doctors, preschools and even day care centers to be involved, said Dr. Stephen Daniels, a University of Colorado pediatrician and a spokesman for the American Heart Association.
Parents who are concerned about a child’s weight should talk with their child’s doctor, because it may be hard to tell what is normal at various ages, and appearances can be misleading. No child should be placed on a diet without a doctor’s advice, the federal Centers for Disease Control and Prevention advises. To help keep kids healthy, balance the calories from food and beverages with how much exercise a child gets – some weight gain is normal, the CDC says.
“You can change your fate by things that you do early in life,” with more exercise and eating a healthy diet, Daniels said. “Once it occurs, obesity is really hard to treat. So the idea is we should really work hard to prevent it.”