title: The role of fat and lean mass in bone loss in older men: findings from the CHAMP study.
abstract: OBJECTIVE
  Weight loss is associated with bone loss; however, it is unclear whether loss of fat or loss of lean body mass plays the key role in this relationship. The aim of this longitudinal analysis was to clarify the relationship between hip BMD, hip BMC and whole body BMC with changes in fat and lean tissue mass in older men.
  
  
  METHODS
  The Concord Health and Aging in Men Project (CHAMP) is a population-based study in Sydney, Australia, involving 1705 men aged 70-97 years. Bone mineral density (BMD) of the total hip, and bone mineral content (BMC) of the hip and whole body (WB), lean mass and fat mass were measured with Dual X-ray Absorptiometry (DXA). Multivariate linear regression models were used to assess relationships.
  
  
  RESULTS
  Over 2.2 years of follow-up, 368(33%) men lost at least 2% of their body weight, which included a mean loss of 0.8 kg/year of lean body mass and 0.9 kg/year of fat body mass. Fat loss was strongly associated with BMD loss in men who lost weight. As a group, weight losers lost 1.0% of hip BMD annually compared to 0.2% in men who gained weight, with each kilo of fat loss associated with 0.6%/year hip BMD loss (p<0.0001). Lean mass was not associated with hip BMD loss in weight losers, however, lean mass change was associated with BMD change in men who gained weight (0.3% hip BMD increase per kilo increase of lean mass p<0.01).
  
  
  CONCLUSIONS
  Maintaining body weight is important for bone health in elderly men. Body fat plays an important role in this relationship, which may reflect the additional metabolic function of adipose tissue.
authors.affiliation: University of Sydney, Sydney, Australia Centre for Education and Research on Ageing: CHAMP Project, Concord Hospital, NSW, Australia. kble3974@uni.sydney.edu.au
authors.forename: Kerrin
authors.initials: K
authors.lastname: Bleicher
authors.forename: Robert G
authors.initials: RG
authors.lastname: Cumming
authors.forename: Vasikaran
authors.initials: V
authors.lastname: Naganathan
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Travison
authors.forename: Philip N
authors.initials: PN
authors.lastname: Sambrook
authors.forename: Fiona M
authors.initials: FM
authors.lastname: Blyth
authors.forename: David J
authors.initials: DJ
authors.lastname: Handelsman
authors.forename: David G
authors.initials: DG
authors.lastname: Le Couteur
authors.forename: Louise M
authors.initials: LM
authors.lastname: Waite
authors.forename: Helen M
authors.initials: HM
authors.lastname: Creasey
authors.forename: Markus J
authors.initials: MJ
authors.lastname: Seibel
mesh_terms: D050154:Adiposity / Q000502:physiology*; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology*; D001315:Australia; D001823:Body Composition / Q000502:physiology; D015519:Bone Density / Q000502:physiology; D001862:Bone Resorption / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008954:Models, Biological; D011859:Radiography; D013851:Thinness / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology*