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Kids: No more weight and see

A pediatrics panel recommends using the body-mass index as an indicator of early risk.

August 11, 2003|Benedict Carey | Times Staff Writer

Some hide it under loose shirts and baggy pants, and others let it hang out of tight tops and hip-huggers. By high school more children than ever carry around extra weight -- about 15% of them, more than twice the rate of a generation ago. Neither public health warnings nor peer pressure has proved strong enough to slow the trend.

That's why the influential American Academy of Pediatrics last week issued its first-ever policy statement for doctors that focuses primarily on diagnosing and preventing childhood weight problems. In the academy's journal, Pediatrics, experts recommended that doctors talk more frankly with families about weight gain and begin using a diagnostic technique that researchers say is more sensitive to budding weight problems than the naked eye: the body-mass index, or BMI.

Doctors have long used BMI -- a ratio calculated using height and weight -- to diagnose weight-related problems in adults but have relied mostly on growth charts and simple observation for children. In just the last two years, researchers have established age-adjusted BMI levels for children.

Pediatricians hope that the measure will tip off parents early, as their children begin adding extra pounds, and perhaps even help older children think in terms of physical fitness rather than obsessing over the bathroom scale.

That is, if BMI doesn't add to the confusion over weight and body image that is already out there.

"There's always the chance that people could misinterpret these measures," said Dr. Marc Jacobson, a pediatrician at Schneider Children's Hospital in New York and an author of the new policy. "But that's what you have a pediatrician for -- to explain it."

Calculating body-mass index itself is relatively easy: Divide a person's weight in pounds by the square of his or her height in inches, then multiply that by 703. An adult with a score between 25 and 30 is considered overweight; one with a score of 30 or above is obese. A person with a score below 18.5 is considered underweight.

The formula is not foolproof. Fit people who are muscular may score 25 or higher, even though they're in very good shape, because muscle weighs more than fat. But the score can also reveal developing weight problems in people who do not look fat.

Estimating risk based on BMI is trickier in children, however, because they're developing so fast. As many parents know, a child who looks chubby at age 7 can shoot up several inches and look skateboard skinny by age 9. To follow this moving target, nutrition researchers at the Centers for Disease Control and Prevention have developed BMI charts based on age and gender. A child whose score falls in the top 15% of this scale is considered at risk of a weight problem; those in the top 5% are considered overweight. For example, a 7-year-old girl who is 4 feet and 65 pounds would be considered at risk for becoming overweight.

Yet miscalculating height by just 0.75 inches or weight by a pound or two might mean the difference between a healthy reading and a child classified as "at risk."

This in turn could trigger dietary recommendations and warnings about weight that could backfire, said some doctors.

"You have to be very careful in doing the calculation and in making sure the treatment doesn't lead to an over-controlling situation, which might help create eating disorders," said Nancy Krebs, a Colorado pediatrician who heads the Academy of Pediatrics' nutrition committee. Krebs said a high BMI score in a child is only a sign of trouble, not a diagnosis. "It's helping you see increases in weight earlier than you would otherwise, so you can do some prevention."

In particular, the academy's policy calls on doctors to advise families on healthy food choices, schedule time for physical activity and set limits on TV or video watching (no more than two hours a day). The statement also urges doctors to "encourage, support and protect breast-feeding." Breast-fed children are less likely to develop weight problems than those who were raised on formula, studies have found.

The steadily creeping weight gain of American children has been so subtle over the past generation that a slightly pudgy physique has begun to look average.

"I think a lot of us have simply forgotten what normal weight looks like," said Dr. John Sattenspiel, a family doctor in Salem, Ore. "To me, kids who have normal or healthy BMIs look scrawny. Sometimes their parents actually bring them in because people are saying, 'That child looks too skinny.' "

Meanwhile, children who are quietly adding extra weight become increasingly difficult to treat each passing year, doctors said. Their metabolism can reset to accommodate their larger size, making weight loss physiologically more difficult. Also, their eating habits often become more difficult to change.

"In some cases," Jacobson said, "the whole family may have to change its behavior -- change what foods it brings into the house, how often it goes out to eat, how often the TV is on."