title: Fat mass loss predicts gain in physical function with intentional weight loss in older adults.
abstract: BACKGROUND
  Clinical recommendation of weight loss (WL) in older adults remains controversial, partially due to concerns regarding lean mass loss and potential loss of physical function. The purpose of this study is to determine the independent associations between changes in fat and lean mass and changes in physical function in older, overweight, and obese adults undergoing intentional WL.
  
  
  METHODS
  Data from three randomized-controlled trials of intentional WL in older adults with similar functional outcomes (short physical performance battery and Pepper assessment tool for disability) were combined. Analyses of covariance models were used to investigate relationships between changes in weight, fat, and lean mass (acquired using dual-energy x-ray absorptiometry) and changes in physical function.
  
  
  RESULTS
  Overall loss of body weight was -7.8 ± 6.1 kg (-5.6 ± 4.1 kg and -2.7 ± 2.4 kg of fat and lean mass, respectively). In all studies combined, after adjustment for age, sex, and height, overall WL was associated with significant improvements in self-reported mobility disability (p < .01) and walking speed (p < .01). Models including change in both fat and lean mass as independent variables found only the change in fat mass to significantly predict change in mobility disability (β[fat] = 0.04; p < .01) and walking speed (β[fat] = -0.01; p < .01).
  
  
  CONCLUSIONS
  Results from this study demonstrate that loss of body weight, following intentional WL, is associated with significant improvement in self-reported mobility disability and walking speed in overweight and obese older adults. Importantly, fat mass loss was found to be a more significant predictor of change in physical function than lean mass loss.
authors.affiliation: Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina 27157, USA. kbeavers@wakehealth.edu
authors.forename: Kristen M
authors.initials: KM
authors.lastname: Beavers
authors.forename: Michael E
authors.initials: ME
authors.lastname: Miller
authors.forename: W Jack
authors.initials: WJ
authors.lastname: Rejeski
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Nicklas
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Krichevsky
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Kritchevsky
mesh_terms: D000273:Adipose Tissue / Q000473:pathology*; D000368:Aged; D000375:Aging / Q000473:pathology* / Q000502:physiology*; D001823:Body Composition; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009765:Obesity / Q000473:pathology / Q000503:physiopathology / Q000628:therapy; D050177:Overweight / Q000473:pathology / Q000503:physiopathology / Q000628:therapy; D010809:Physical Fitness / Q000502:physiology*; D012307:Risk Factors; D055948:Sarcopenia / Q000473:pathology / Q000503:physiopathology; D016138:Walking / Q000502:physiology; D015431:Weight Loss / Q000502:physiology*; D061217:Weight Reduction Programs