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Researchers at the University of Bristol in Great Britain have devised a new measure to determine at infancy the likelihood of obesity. The "ponderal index" divides an infant's weight in kilograms by its length in centimeters cubed. Although it is similar to the body mass index, which is weight in kilograms divided by height in meters squared, the ponderal index is believed to offer a gauge that is relative to body composition. Researchers used dual-energy x-ray absorptiometry to measure lean body mass and percentage of body fat in more than 6000 children between 9 and 10 years old. As predicted, fat mass and lean mass increased with birth weight, but there was no connection between birth weight and the ratio of fat to lean mass. Researchers did, however, find that the higher a child's ponderal index was at birth, the greater was the ratio of fat to lean mass at ages 9 to 10. They also determined that a higher ponderal index score meant a higher percentage of body fat. Researchers found that children who were longer at birth had lower percentages of body fat at ages 9 to 10. The study can be found in the October 2006 issue of the American Journal of Clinical Nutrition.
Ms. Farley is a freelance medical writer based in Wakefield, RI.