The Body Composition Laboratory at CNRC

Body weight alone is a crude indicator of growth and development in infants. It takes some amazing technology to determine how much of a baby’s weight gain is fat and how much is bone and muscle. Body composition studies do just that. With the knowledge gained in these studies, scientists can develop better guidelines for determining when a premature baby has grown “enough” to leave the hospital or when a “heavy” child may have an increased risk of heart disease later in life.

The Body Composition Laboratory at the USDA/ARS Children’s Nutrition Research Center (CNRC) provides a complete compliment of body composition measurements in all populations ranging from low-birth-weight infants to adults. The body contents of water, bone mineral, protein and fat are routinely determined. These measurements are used in a number of CNRC research studies and in collaborative research with other scientists and clinicians at the Texas Medical Center. The CNRC laboratory continues to develop and validate new methods for assessing body composition, especially in children. Data from over 3000 children are being used to develop age-, gender- and ethnic-specific body composition references.

One of the laboratory’s newer pieces of equipment allows rapid, non-invasive determination of body fat in infants up to around five months of age including small pre-term infants. Air displacement plethysmography is the technique. It measures body weight and body volume at the same time to calculate the infant’s body density. For two infants of the same weight, the one with the lower density will have more body fat. These measurements become increasingly important as investigators and clinicians discover more about the importance of nutrition and growth during the first six months of life and how the changes in body composition at these ages can influence future health outcomes.