title: One- and two-year change in body composition as measured by DXA in a population-based cohort of older men and women.
abstract: Changing body composition has been suggested as a pathway to explain age-related functional decline. No data are available on the expected changes in body composition as measured by dual-energy X-ray absorptiometry (DXA) in a population-based cohort of older persons. Body composition data at baseline, 1-yr follow-up, and 2-yr follow-up was measured by DXA in 2,040 well-functioning black and white men and women aged 70-79 yr, participants of the Health, Aging, and Body Composition Study. After 2 yr, a small decline in total body mass was observed (men: -0.3%, women: -0.4%). Among men, fat-free mass and appendicular lean soft tissue mass (ALST) decreased by -1.1 and -0.8%, respectively, which was masked by a simultaneous increase in total fat mass (+2.0%). Among women, a decline in fat-free mass was observed after 2 yr only (-0.6%) with no change in ALST and body fat mass. After 2 yr, the decline in ALST was greater in blacks than whites. Change in total body mass was associated with change in ALST (r = +0.58 to +0.70; P < 0.0001). Among participants who lost total body mass, men lost relatively more ALST than women, and blacks lost relatively more ALST than whites. In conclusion, the mean change in body composition after a 1- to 2-yr follow-up was 1-2% with a high interindividual variability. Loss of ALST was greater in men compared with women, and greater in blacks compared with whites, suggesting that men and blacks may be more prone to muscle loss.
authors.affiliation: Institute for Research in Extramural Medicine, Vrije University Medical Center, 1081 BT Amsterdam, The Netherlands.
authors.forename: Marjolein
authors.initials: M
authors.lastname: Visser
authors.forename: Marco
authors.initials: M
authors.lastname: Pahor
authors.forename: Frances
authors.initials: F
authors.lastname: Tylavsky
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Kritchevsky
authors.forename: Jane A
authors.initials: JA
authors.lastname: Cauley
authors.forename: Anne B
authors.initials: AB
authors.lastname: Newman
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Blunt
authors.forename: Tamara B
authors.initials: TB
authors.lastname: Harris
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D000375:Aging / Q000502:physiology*; D044383:Black People; D001823:Body Composition / Q000502:physiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D012727:Sex Characteristics; D013997:Time Factors; D044465:White People