Toward body composition reference data for infants, children, and adolescents

Abstract

Growth charts for weight and height have provided the basis for assessment of children's nutritional status for over half a century, with charts for body mass index (BMI) introduced in the 1990s. However, BMI does not provide information on the proportions of fat and lean mass; and within the past decade, growth charts for children's body composition have been produced by using techniques such as skinfold thicknesses, body circumferences, bioelectrical impedance analysis (BIA), and dual-energy X-ray absorptiometry (DXA). For public health research, BIA and skinfold thicknesses show negligible average bias but have wider limits of agreement than specialized techniques. For patients, DXA is the best individual method, but multicomponent models remain ideal because they address perturbations in lean mass composition. Data can be expressed in age- and sex-specific SD scores, in some cases adjusting for height. Most such reference data derive from high-income countries, but techniques such as air-displacement plethysmography allow infant body composition growth charts to be developed in low- and middle-income settings, where the data may improve understanding of the effects of low birth weight, wasting, and stunting on body composition. Recent studies suggest that between-population variability in body composition may derive in part from genetic factors, suggesting a universal human body composition reference may not be viable. Body composition growth charts may be extended into adult life to evaluate changes in fat and lean mass through the entire life course. These reference data will improve the understanding of the association between growth, body composition, health, and disease.

FIGURE 1

(A) The contribution of lean mass and fat mass to BMI illustrated using a “Hattori chart” that plots fat mass/height² on the y-axis against lean mass/height² on the x-axis (21). Continuous lines represent constant BMI values; dotted lines represent constant %fat values. (B) The distribution of fat mass/height² and lean mass/height² in a sample of children aged 8 y. Children with the same BMI value may vary in their %fat (“A” vs. “B”), whereas those with the same %fat value may vary substantially in their BMI (“B” vs. “C”). Reproduced from reference with permission. %fat, percentage of fat.

FIGURE 2

Body composition growth charts using the 4-component model in UK children and adolescents aged 5–20 y. The 2nd, 9th, 25th, 50th, 75th, 91st, and 98th percentiles are displayed in ascending order. Left panels: males; right panels: females. Reproduced from reference with permission.

FIGURE 3

Body composition reference data from birth to 6 mo of age for female infants from Jimma, Ethiopia, obtained by using air-displacement plethysmography. Individual charts are available for lean mass (A), fat mass (B), lean mass index (C), and fat mass index (D). The 2nd, 9th, 25th, 50th, 75th, 91st, and 98th percentiles are displayed in ascending order. Reproduced from reference with permission.

FIGURE 4

Average birth weights of neonates categorized according to parental ethnicity. Compared with neonates of 2 European parents, those of 2 Indian parents had substantially lower birth weight. The weights of neonates of parents who differed in their ethnicity were intermediate. Indian mothers do not exert a fixed “constraint” on the fetal growth of their offspring; rather, European fathers can promote the growth of their offspring. Indian fathers contribute to the lower birth weights of their infants, shown by their restraining the growth of offspring of European mothers. Reproduced from reference with permission. F, European father; f, Indian father; M, European mother; m, Indian mother.