For many obese
adults, the die was cast by the time they were 5 years old. A major new study of
more than 7,000 children has found that a third of children who were overweight
in kindergarten were obese by eighth grade. And almost every child who was very
obese remained that way.
Some obese or
overweight kindergartners lost their excess weight, and some children of normal
weight got fat over the years. But every year, the chances that a child would
slide into or out of being overweight or obese diminished. By age 11, there
were few additional changes: Those who were obese or overweight stayed that way,
and those whose weight was normal did not become fat.
“The main message
is that obesity is established very early in life, and that it basically tracks
through adolescence to adulthood,” said Ruth Loos, a professor of preventive
medicine at the Icahn School of Medicine at Mount Sinai in New York, who was
not involved in the study.
These results,
surprising to many experts, arose from a rare study that tracked children’s
body weight for years, from kindergarten through eighth grade. Experts say they
may reshape approaches to combating the nation’s obesity epidemic, suggesting
that efforts must start much earlier and focus more on the children at greatest
risk.
The study
involved 7,738 children from a nationally representative sample. Researchers
measured the children’s height and weight seven times from kindergarten to
eighth grade.
When the children
entered kindergarten, 12.4 percent were obese — defined as having a body mass
index at or above the 95th percentile — and 14.9 percent were overweight, with
a B.M.I. at or above the 85th percentile. By eighth grade, 20.8 percent were
obese and 17 percent were overweight. Half of the obese kindergartners were
obese when they were in eighth grade, and nearly three-quarters of the very
obese kindergartners were obese in eighth grade. The risk that fat
kindergartners would be obese in eighth grade was four to five times that of
their thinner classmates, the study found.
Race, ethnicity
and family income mattered in younger children, but by the time the overweight children
were 5 years old, those factors no longer affected their risk of being fat in
later years.
Some obesity
researchers said the new study following kindergartners over the years also
hinted at another factor: the powerful influence of genetics on obesity,
something that can be a challenge to overcome
And, he said, a
number of randomized studies involving young children have shown that it is
possible to stop or reverse excess weight gain. One, for example, had some fat
children ages 4 to 7 reduce their television and computer viewing time, and had
others keep theirs the same. Children in the intervention group — especially
those from poorer families — consumed fewer calories, and their body mass index
fell.
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