TUESDAY, July 30 (HealthDay News) -- Overweight kids may be
consuming far more calories than their doctors or parents realize,
a new study suggests.
The study, which is published in the July 30 online issue of
The Lancet Diabetes & Endocrinology, updates the
mathematical model doctors use to calculate the daily calorie needs
of children and adolescents.
The new model tries to more accurately estimate the energy
requirements for growing girls and boys. It also accounts for kids'
higher metabolisms, relative to adults, and takes into account the
drop in physical activity that happens with age as frenetic
toddlers turn into sluggish teens. And last, study authors factor
in the increased energy required to maintain a bigger body size
In sum, the model predicts that it takes far more calories for
children to gain weight than experts had realized.
For example, the old model estimates that for a girl who's a
normal weight at age 5 to become 22 pounds overweight by the time
she's 10, she'd need to eat around 40 extra calories a day -- the
equivalent of the calories in a small apple.
The new model predicts that she'd actually need to eat far more
than that -- about 400 extra calories a day, or the calories in a
medium serving of fast-food french fries -- to get the same
That's one case, but the number of calories it takes to gain
weight is slightly different for boys and girls at every age.
"It's a bit of a moving target," admitted study author Kevin
Hall, a senior investigator at the U.S. National Institute of
Diabetes and Digestive and Kidney Diseases. "The point of these
examples is that the excess calorie consumption is much larger than
most folks would have suggested in the past."
Using historical data collected by the U.S. Centers for Disease
Control and Prevention, Hall and his co-authors calculated that
children today are an average of 13 pounds heavier than kids were
in the late 1970s, before the start of the obesity epidemic. To
gain those extra pounds, kids have consumed about 200 more calories
At different ages, and depending on the amount of weight a child
has gained, the differences can be even more stark.
For example, the model estimates than an 11-year-old boy who is
about 18 pounds overweight has eaten roughly 320 more calories a
day than his healthy-weight peers. Meanwhile, a girl who is the
same age and also 18 pounds overweight has taken in an extra 301
Hall said the new numbers give parents and doctors a road map
for "how we got here" with overweight and obese kids, but they
aren't exactly the way back to a normal weight. Kids who cut
calories by the amount their currently overeating may stop gaining,
for example, but they'd likely need to cut even more to shed their
Dr. David Katz, director of the Yale Prevention Research Center,
praised the new model, and said it clarifies energy intake levels
needed to achieve public health goals.
"Importantly, given the rather large calorie excesses fueling
childhood obesity, this model is a rebuttal to the food industry
arguments that exercise alone can be the answer," said Katz, who is
also editor of the journal
"For our kids to achieve healthy weight, control of calories in,
not just calories out, will have to be part of the formula," said
Katz, who was not involved in the research.
But there's some good news in the new numbers, too. As doctors
and parents have long suspected, some kids appear to be able to
outgrow their extra pounds when they shoot up in height during
puberty, though that feat may be easier for boys than girls,
because boys gain more calorie-burning muscle during puberty than
"If you haven't reached puberty and haven't yet reached that
growth spurt, that might be the ideal time to institute a weight
management intervention to harness the power of the growth to
decrease fat mass and increase fat-free mass," said study author
To learn more about childhood obesity, head to the
U.S. National Library of Medicine.