Trajectories of Fat Mass Index, Fat Free–Mass Index, and Waist Circumference in Children

Project HeartBeat!


      Body composition and fat distribution change dramatically during adolescence. Data based on longitudinal studies to describe these changes are limited. The aim of this study was to describe age-related changes in fat free–mass index (FFMI) and fat mass index (FMI), which are components of BMI, and waist circumference (WC) in participants of Project HeartBeat!, a longitudinal study of children.


      Anthropometric measurements and body composition data were obtained in a mixed longitudinal study of 678 children (49.1% female, 20.1% black), initially aged 8, 11, and 14 years, every 4 months for 4 years (1991–1995). Trajectories of change from ages 8 to 18 years were measured for FFMI, FMI, and WC. Because of the small number of observations for black participants, trajectories for this group were limited to ages 8.5–15 years.


      Body mass index, FFMI, and WC increased steadily with age for all race–gender cohorts. However, in nonblack girls, FFMI remained constant after about age 16 years. For black boys and girls, FFMI was similar at age 8.5 years but increased more steeply for black boys by age 15 years. In girls, FMI showed an upward trend until shortly after age 14 years, when it remained constant. In boys, FMI increased between age 8 years and age 10 years, and then decreased.


      The extent to which each component of BMI contributes to the changes in BMI depends on the gender, race, and age of the individual. Healthcare providers need to be aware that children who show upward deviation of BMI or BMI percentiles may have increases in their lean body mass rather than in adiposity.
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        • National Center for Health Statistics
        2000 CDC growth charts: United States.
        • Franklin M.F.
        Comparison of weight and height relations in boys from 4 countries.
        Am J Clin Nutr. 1999; 70: 157S-162S
        • Demerath E.W.
        • Schubert C.M.
        • Maynard L.M.
        • et al.
        Do changes in body mass index percentile reflect changes in body composition in children?.
        Pediatrics. 2006; 117: e487-e495
        • Freedman D.S.
        • Ogden C.L.
        • Berenson G.S.
        • Horlick M.
        Body mass index and body fatness in childhood.
        Curr Opin Clin Nutr Metab Care. 2005; 8: 618-623
        • Maynard L.M.
        • Wisemandle W.
        • Roche A.F.
        • Chumlea W.C.
        • Guo S.S.
        • Siervogel R.M.
        Childhood body composition in relation to body mass index.
        Pediatrics. 2001; 107: 344-350
        • Kuk J.L.
        • Katzmarzyk P.T.
        • Nichaman M.Z.
        • Church T.S.
        • Blair S.N.
        • Ross R.
        Visceral fat is an independent predictor of all-cause mortality in men.
        Obesity (Silver Spring). 2006; 14: 336-341
        • Wiklund P.
        • Toss F.
        • Weinehall L.
        • et al.
        Abdominal and gynoid fat mass are associated with cardiovascular risk factors in men and women.
        J Clin Endocrinol Metab. 2008; 93: 4360-4366
        • Freedman D.S.
        • Wang J.
        • Maynard L.M.
        • et al.
        Relation of BMI to fat and fat-free mass among children and adolescents.
        Int J Obes (Lond). 2005; 29: 1-8
        • Nakao T.
        • Komiya S.
        Reference norms for a fat-free mass index and fat mass index in the Japanese child population.
        J Physiol Anthropol Appl Human Sci. 2003; 22: 293-298
        • Mueller W.H.
        • Harrist R.B.
        • Doyle S.R.
        • Ayars C.L.
        • Labarthe D.R.
        Body measurement variability, fatness, and fat-free mass in children 8, 11, and 14 years of age: Project HeartBeat!.
        Am J Hum Biol. 1999; 11: 69-78
        • Labarthe D.R.
        • Nichaman M.Z.
        • Harrist R.B.
        • Grunbaum J.A.
        • Dai S.
        Development of cardiovascular risk factors from ages 8 to 18 in Project HeartBeat! Study design and patterns of change in plasma total cholesterol concentration.
        Circulation. 1997; 95: 2636-2642
        • Lohman T.G.
        • Roche A.F.
        • Martorell R.
        Anthropometric standardization reference manual.
        Human Kinetics Press, Champaign IL1988
        • Guo S.M.
        • Roche A.F.
        • Houtkooper L.
        Fat-free mass in children and young adults predicted from bioelectric impedance and anthropometric variables.
        Am J Clin Nutr. 1989; 50: 435-443
        • Dai S.
        • Labarthe D.R.
        • Grunbaum J.A.
        • Harrist R.B.
        • Mueller W.H.
        Longitudinal analysis of changes in indices of obesity from age 8 years to age 18 years.
        Am J Epidemiol. 2002; 156: 720-729
        • Hattori K.
        • Tahara Y.
        • Moji K.
        • Aoyagi K.
        • Furusawa T.
        Chart analysis of body composition change among pre- and postadolescent Japanese subjects assessed by underwater weighing method.
        Int J Obes Relat Metab Disord. 2004; 28: 520-524
        • Chumlea W.C.
        • Siervogel R.M.
        • Roche A.F.
        • Webb P.
        • Rogers E.
        Increments across age in body composition for children 10 to 18 years of age.
        Hum Biol. 1983; 55: 845-852
        • Wells J.C.
        • Coward W.A.
        • Cole T.J.
        • Davies P.S.
        The contribution of fat and fat-free tissue to body mass index in contemporary children and the reference child.
        Int J Obes Relat Metab Disord. 2002; 26: 1323-1328
        • Dekkers J.C.
        • Podolsky R.H.
        • Treiber F.A.
        • Barbeau P.
        • Gutin B.
        • Snieder H.
        Development of general and central obesity from childhood into early adulthood in African American and European American males and females with a family history of cardiovascular disease.
        Am J Clin Nutr. 2004; 79: 661-668
        • Huang T.T.
        • Johnson M.S.
        • Figueroa-Colon R.
        • Dwyer J.H.
        • Goran M.I.
        Growth of visceral fat, subcutaneous abdominal fat, and total body fat in children.
        Obes Res. 2001; 9: 283-289
        • Ogden C.L.
        • Carroll M.D.
        • Curtin L.R.
        • McDowell M.A.
        • Tabak C.J.
        • Flegal K.M.
        Prevalence of overweight and obesity in the United States, 1999–2004.
        JAMA. 2006; 295: 1549-1555