Reflecting Diversity, U.S. Issues New Growth Charts
WASHINGTON — Federal health officials issued new pediatric growth charts Tuesday that more accurately reflect the nation’s diversity and, for the first time, include a tool to identify children who are at risk of obesity.
More than half of all Americans are overweight, and the number of American children who are overweight has doubled in the last 20 years, federal officials say.
The new charts use the body mass index, or BMI, a single number that evaluates an individual’s weight in relation to height.
But unlike the BMI numbers for adults, which do not change, the new BMI measures for children continue to reflect differences as children grow.
“The BMI is an early warning signal that is helpful as early as age 2,” said Health and Human Services Secretary Donna Shalala, speaking at a national nutrition meeting here. “This means that parents have an opportunity to change their children’s eating habits before a weight problem ever develops.”
The BMI data would be used in conjunction with a series of revised growth charts that replace the original ones. First developed in 1977, the earlier charts were based on a private study of primarily white, formula-fed, middle-class infants from southwestern Ohio.
The latest charts were developed from a more representative national sample. But officials of the Centers for Disease Control and Prevention said the results are not dramatically different--in large part because environmental influences have more to do with growth than do genetic factors.
In fact, “the heights appear to be quite similar because there has been very little change in heights in the pediatric population over the past 20 to 25 years,” said Dr. Robert Kuczmarski, of CDC’s National Center for Health Statistics.
“There are some racial and ethnic differences in growth potential, which appear to be small and not genetically determined,” he added. “If children are provided with proper nutrition, access to health care and living conditions similar to those of more economically privileged children, their growth will be similar.”
The BMI measures, which the CDC described as “the single most important new feature” of the revised charts, will be especially useful after babies become toddlers, the agency said.
This is the time when they can begin to exhibit a tendency toward becoming overweight, said Dr. Tom Jaksic, a pediatric surgeon at Children’s Hospital in Boston and a member of the nutrition committee of the American Academy of Pediatrics.
While a chubby baby often is regarded as healthy, “a chubby toddler isn’t necessarily a healthier or potentially healthier toddler,” Jaksic said.
About 11% of adolescents--those ages 12 to 18--are overweight, a rise of 6% since 1980.
The percentage of overweight children ages 6 to 11 is even higher than their teenage counterparts: 14% of them are overweight.
The BMI is an indicator for assessing body fat and in recent years has become the most common method of tracking weight problems among adults. The BMI numbers are calculated by multiplying weight in pounds by 703 and dividing the result by height in inches squared.
For most adults, a BMI of 25 of higher is regarded as overweight, while 30 or above is considered obese. There is more latitude among children, however, because of gender, age and growth patterns. And their BMIs--and what they mean in terms of obesity--will change over time.
For example, a 5-foot 11-year-old boy weighing 120 pounds would have a BMI of 23.4, which would be considered overweight, a possible sign of potential obesity--although much would depend on his ultimate height, CDC said.
At age 18, for example, to be regarded as overweight, he would need a BMI of 29.1 at a height of 5 feet 10 inches and a weight of 203 pounds.
“That’s why a pediatrician will have to take other factors into account when [the child] is 11, including his height curve and the height of his parents,” one CDC official said.
Children identified early as being at risk for obesity may be easier to help than they would be as overweight adults, Jaksic said.
“A lot of work needs to be done in trying to eliminate obesity as a health problem,” he said. “It’s quite difficult to do, even in children, because most eating habits are familial.”
How to Calculate BMI
Scientists use a body mass index figure to determine who they say is overweight or obese. To determine body mass index, multiply weight in pounds by 703. Then divide that result by height in inches squared. Examples:
* A person, male or female, who is 5 feet, 1 inch and 132 pounds would have a body mass index of 25 and be considered overweight. At 158 pounds, the person would have a BMI of 30 and be considered obese.
* A 145-pound, 5-foot-4 person would have a BMI of 25. At 174 pounds, the BMI would be 30.
* A 159-pound, 5-foot-7 person would have a BMI of 25. At 191 pounds, the BMI would be 30.
* A 174-pound, 5-foot-10 person would have a BMI of 25. At 209 pounds, the BMI would be 30.
* A 189-pound, 6-foot-1 person would have a BMI of 25. At 227 pounds, the BMI would be 30.
Source: Associated Press
