title: Longitudinal changes in body composition in older men and women: role of body weight change and physical activity.
abstract: BACKGROUND
  Estimates of body-composition change in older adults are mostly derived from cross-sectional data.
  
  
  OBJECTIVE
  We examined the natural longitudinal patterns of change in fat-free mass (FFM) and fat mass (FM) in older adults and explored the effect of physical activity, weight change, and age on these changes.
  
  
  METHODS
  The body composition measured by hydrodensitometry and the level of sports and recreational activity (SRA) of 53 men and 78 women with a mean (+/-SD) initial age of 60.7 +/- 7.8 y were examined on 2 occasions separated by a mean (+/-SD) time of 9.4 +/- 1.4 y.
  
  
  RESULTS
  FFM decreased in men (2.0% per decade) but not in women, whereas FM increased similarly in both sexes (7.5% per decade). Levels of SRA decreased more in men than in women over the follow-up period. Baseline age and level of SRA were inversely and independently associated with changes in FM in women only. Neither age nor level of SRA was associated with changes in FFM in men or women. Weight-stable subjects lost FFM. FFM accounted for 19% of body weight in those who gained weight, even in the presence of decreased levels of SRA. Loss of FFM (33% of body weight) was pronounced in those who lost weight, despite median SRA levels >4184 kJ/wk.
  
  
  CONCLUSIONS
  On average, FM increased; however, the increase in women was attenuated with advancing age. The decrease in FFM over the follow-up period was small and masked the wide interindividual variation that was dependent on the magnitude of weight change. The contribution of weight stability, modest weight gains, or lifestyle changes that include regular resistance exercise in attenuating lean-tissue loss with age should be explored.
authors.affiliation: Nutrition, Exercise Physiology and Sarcopenia Laboratory, Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA. ghughes@hnrc.tufts.edu
authors.forename: Virginia A
authors.initials: VA
authors.lastname: Hughes
authors.forename: Walter R
authors.initials: WR
authors.lastname: Frontera
authors.forename: Ronenn
authors.initials: R
authors.lastname: Roubenoff
authors.forename: William J
authors.initials: WJ
authors.lastname: Evans
authors.forename: Maria A Fiatarone
authors.initials: MA
authors.lastname: Singh
mesh_terms: D000273:Adipose Tissue; D000375:Aging / Q000502:physiology*; D001823:Body Composition; D001835:Body Weight; D003430:Cross-Sectional Studies; D015444:Exercise; D005260:Female; D006304:Health Status; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged