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 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 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.
RACE: 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 and Native Americans and mixed-race children.
By eighth grade, 17 percent of black children had become obese,
compared to 14 percent of Hispanics and 10 percent of whites and children of
other races.
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.
BIRTHWEIGHT: 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 study's findings do not mean that it's 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
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. 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.
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 a child
gets from food and beverages with how much exercise he or she gets to allow
enough for normal growth — 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."
