Those efforts to fight obesity in schools? Think younger.
A new study finds that much of a childs 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 on, 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 latest study, which was published in this weeks 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:
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.
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.
From kindergarten through eighth grade, the prevalence of obesity increased by 65 percent among whites, 50 percent among Hispanics, almost 120 percent among blacks and more than 40 percent among others – Asians, Pacific Islanders, American Indians and mixed-race children. By eighth grade, 17 percent of black children had become obese, compared with 14 percent of Hispanics and 10 percent of whites and children of other races.
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.
The studys findings do not mean that its too late for schools to act, but their best tactic may be to focus on kids who are overweight and try to encourage exercise and healthy eating, Cunningham said.
The work also shows the need for parents, doctors, preschools and even child-care centers to be involved, said Dr. Stephen Daniels, a spokesman for the American Heart Association.
In children, obesity and overweight are defined by how a child ranks on growth charts that compare them to other kids the same age and gender. Kids at or above the 85th percentile are considered overweight, and obese at the 95th percentile or above. To help keep kids healthy, balance the calories a child gets from food and beverages with how much exercise the child gets to allow enough for normal growth, 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.