title: Effect of Body Composition Methodology on Heritability Estimation of Body Fatness.
abstract: Heritability estimates of human body fatness vary widely and the contribution of body composition methodology to this variability is unknown. The effect of body composition methodology on estimations of genetic and environmental contributions to body fatness variation was examined in 78 adult male and female monozygotic twin pairs reared apart or together. Body composition was assessed by six methods - body mass index (BMI), dual energy x-ray absorptiometry (DXA), underwater weighing (UWW), total body water (TBW), bioelectric impedance (BIA), and skinfold thickness. Body fatness was expressed as percent body fat, fat mass, and fat mass/height2to assess the effect of body fatness expression on heritability estimates. Model-fitting multivariate analyses were used to assess the genetic and environmental components of variance. Mean BMI was 24.5 kg/m2(range of 17.8-43.4 kg/m2). There was a significant effect of body composition methodology (p<0.001) on heritability estimates, with UWW giving the highest estimate (69%) and BIA giving the lowest estimate (47%) for fat mass/height2. Expression of body fatness as percent body fat resulted in significantly higher heritability estimates (on average 10.3% higher) compared to expression as fat mass/height2(p=0.015). DXA and TBW methods expressing body fatness as fat mass/height2gave the least biased heritability assessments, based on the small contribution of specific genetic factors to their genetic variance. A model combining DXA and TBW methods resulted in a relatively low FM/ht2heritability estimate of 60%, and significant contributions of common and unique environmental factors (22% and 18%, respectively). The body fatness heritability estimate of 60% indicates a smaller contribution of genetic variance to total variance than many previous studies using less powerful research designs have indicated. The results also highlight the importance of environmental factors and possibly genotype by environmental interactions in the etiology of weight gain and the obesity epidemic.
authors: Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, 711 Washington St., Boston, MA 02111, USA.
authors: Sonya J
authors: SJ
authors: Elder
authors: Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, 711 Washington St., Boston, MA 02111, USA.
authors: Susan B
authors: SB
authors: Roberts
authors: Department of Foods and Nutrition, Purdue University, 700 W. State St., West Lafayette, IN 47907, USA.
authors: Megan A
authors: MA
authors: McCrory
authors: Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, 711 Washington St., Boston, MA 02111, USA.
authors: Sai Krupa
authors: SK
authors: Das
authors: Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, 711 Washington St., Boston, MA 02111, USA.
authors: Paul J
authors: PJ
authors: Fuss
authors: Division of Endocrinology, Diabetes, and Metabolism, Tufts Medical Center, 800 Washington St, #268, Boston, MA 02111, USA.
authors: Anastassios G
authors: AG
authors: Pittas
authors: Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, 711 Washington St., Boston, MA 02111, USA.
authors: Andrew S
authors: AS
authors: Greenberg
authors: Pennington Biomedical Research Institute, 6400 Perkins Rd., Baton Rouge, LA 70808-4124, USA.
authors: Steven B
authors: SB
authors: Heymsfield
authors: Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, 711 Washington St., Boston, MA 02111, USA.
authors: Bess
authors: B
authors: Dawson-Hughes
authors: Department of Psychology, University of Minnesota, Elliott Hall, 75 East River Rd., Minneapolis, MN 55455, USA.
authors: Thomas J
authors: TJ
authors: Bouchard
authors: Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, 711 Washington St., Boston, MA 02111, USA.
authors: Edward
authors: E
authors: Saltzman
authors: Virginia Institute of Psychiatric and Behavioral Genetics and Department of Psychiatry, Virginia Commonwealth University, 800 Leigh St, Ste 1-110, Richmond, VA 23298, USA.
authors: Michael C
authors: MC
authors: Neale
keywords: adiposity; body composition; genetics; heritability; twins