ARS | Publication request: Effect of body composition methodology on estimates of fat mass heritability

Submitted to: Obesity
Publication Type: Abstract
Publication Acceptance Date: June 30, 2008
Publication Date: October 3, 2008
Citation: Elder, S.J., Neale, M.C., Das, S., Fuss, P.J., McCrory, M.A., Heymsfield, S.B., Saltzman, E., Roberts, S. 2008. Effect of body composition methodology on estimates of fat mass heritability. Obesity. 16(S1):S256.

Technical Abstract: Background: Body fatness is influenced by both genetic and environmental factors. Previous studies have produced a wide range of estimates for the heritability of body fatness, ranging from 0.34-0.90 for body mass index (BMI), 0.59-0.83 for percent body fat, and 0.45-0.71 for fat mass. Little attention has been given to whether different body composition methods result in different heritability estimates of body fatness. This study was designed to compare estimates of genetic, common environmental, and unique environmental components of variance for body fatness as measured by six widely-used body composition methods. Methods: Fat mass of 29 monozygotic twin pairs reared apart and 49 monozygotic twin pairs reared together was measured by five methods: anthropometry (ANT), dual energy x-ray absorptiometry (DXA), underwater weighing (UWW), total body water (TBW), and bioelectric impedance (BIA). In addition, BMI was assessed. Genetic, common environmental, and unique environmental effects were estimated using the structural equation model-fitting software program Mx. Results: Six body composition methods resulted in heritability estimates of body fatness (expressed as fat mass/height^2 or mass/height^2 for BMI) which ranged from 0.51-0.77 and differed significantly from one another (p=0.001). TBW and DXA resulted in heritability estimates (0.64 and 0.63 respectively) with the least variance associated with genetic factors specific to the methodology. In contrast, a significant portion of the variance in body fatness assessed by ANT, UWW, BIA and BMI was accounted for by latent genetic factors specific to the methodology, indicating that these methods are less suitable for assessing the heritability of body fatness. Conclusions: TBW and DXA resulted in heritability estimates with the least methodology-specific genetic variance, and could therefore be considered the most appropriate methods for body composition heritability studies. Using these methods, the heritability of body fatness in this study was 0.63-0.64, which is lower than values typically reported. Research Support: NIDDK 5 R01 DK046124-5, NIH MH-65322, NIH/NHLBI 5T32 HL069772