title: Eight-year longitudinal changes in body composition in healthy Swiss adults.
abstract: OBJECTIVE
  Significant changes in body composition occur during lifetime. This longitudinal study (8.0 +/- 0.8 yrs) in a cohort of healthy sedentary and physically active men (n = 78) and women (n = 53), aged 20 to 74 yr describes: 1) the longitudinal changes in weight and body composition and 2) their associations with age and physical activity.
  
  
  METHODS
  Fat-free mass (FFM) and body fat (BF) were assessed by bioelectrical impedance analysis (BIA). Subjects who regularly performed >3 hours per week of endurance type physical activity were classified as "Active". Others were classified as "Sedentary". Subjects were also separated by age (<45 yr vs > or =45 yr).
  
  
  RESULTS
  FFM increased by 1.7 +/- 2.8 kg in men <45 yr who gained 4.0 +/- 5.0 kg of body weight and was maintained (0.5 +/- 1.6 kg) in women <45 y who gained 1.6 +/- 3.0 kg of weight. A weight gain of 1.2 +/- 3.3 kg in men > or =45 yr was accompanied by stable FFM (-0.1 +/- 2.3 kg), and of 1.0 +/- 3.2 kg was accompanied by a loss of FFM in women > or =45 yr. In active men > or =45 yr, maintenance of FFM was associated with smaller weight gains than in sedentary; sedentary men > or =45 yr decreased FFM with larger weight gains than active subjects. Sedentary women <45 yr were able to gain FFM; the active women maintained, but did not gain FFM with smaller weight gains than in sedentary women. FFM decreased in >/=45 yr women despite of small weight gains.
  
  
  CONCLUSIONS
  Weight change is clearly associated with a change in FFM. Weight gain is necessary to offset age-related FFM loss between 20 and 74 yrs. In active men, a FFM increase was associated with less weight gain than sedentary men. Future studies should evaluate the threshold of weight change and the level of physical activity necessary to prevent age-related losses of FFM.
authors.affiliation: Clinical Nutrition, Geneva University Hospital, 1211 Geneva, Switzerland.
authors.forename: Ursula G
authors.initials: UG
authors.lastname: Kyle
authors.forename: Katarina
authors.initials: K
authors.lastname: Melzer
authors.forename: Bengt
authors.initials: B
authors.lastname: Kayser
authors.forename: Michel
authors.initials: M
authors.lastname: Picard-Kossovsky
authors.forename: Gerald
authors.initials: G
authors.lastname: Gremion
authors.forename: Claude
authors.initials: C
authors.lastname: Pichard
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology*; D001823:Body Composition / Q000502:physiology*; D001835:Body Weight / Q000502:physiology*; D015331:Cohort Studies; D017097:Electric Impedance; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism*; D011795:Surveys and Questionnaires; D013557:Switzerland