title: Estimates of body composition with dual-energy X-ray absorptiometry in adults.
abstract: BACKGROUND
  Little is known about the distributions of percentage body fat (PBF), total body fat (TBF), and fat-free mass (FFM) in the adult population in the United States.
  
  
  OBJECTIVE
  We sought to estimate the means and percentile cutoffs of PBF, TBF, and FFM and to assess the differences by sex, age, race-ethnicity, and body mass index in US adults.
  
  
  METHODS
  Data from the National Health and Nutrition Examination Survey (NHANES), which were collected during the 6-y period from 1999 to 2004 and comprise a large nationally representative sample of the US population, were analyzed (n = 6559 men and 6507 nonpregnant women). TBF and FFM were measured by using dual-energy X-ray absorptiometry. PBF was calculated as TBF divided by total mass multiplied by 100.
  
  
  RESULTS
  There were large differences between men and women in unadjusted mean PBF (28.1% compared with 40.0%, P < 0.001), TBF (25.4 compared with 30.8 kg, P < 0.001), and FFM (62.3 compared with 44.0 kg, P < 0.001); the sex differences persisted across all body mass index categories after adjustment for age and race-ethnicity (all P < 0.001). The common percentile cutoffs of PBF, TBF, and FFM were estimated by sex, race-ethnicity, and age groups. Equations for the estimation of PBF (R(2) = 0.85), TBF (R(2) = 0.94), and FFM (R(2) = 0.94) according to demographic characteristics and simple anthropometric measures were generated.
  
  
  CONCLUSIONS
  The estimates of means and percentile cutoffs for PBF, TBF, and FFM, on the basis of NHANES 1999-2004 dual-energy X-ray absorptiometry data, provide a reference in the US adult population.
authors.affiliation: Division of Adult and Community Health, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA. cli@cdc.gov
authors.forename: Chaoyang
authors.initials: C
authors.lastname: Li
authors.forename: Earl S
authors.initials: ES
authors.lastname: Ford
authors.forename: Guixiang
authors.initials: G
authors.lastname: Zhao
authors.forename: Lina S
authors.initials: LS
authors.lastname: Balluz
authors.forename: Wayne H
authors.initials: WH
authors.lastname: Giles
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044383:Black People; D001823:Body Composition; D050218:Body Fat Distribution; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D017058:Mexican Americans; D008875:Middle Aged; D044465:White People