title: Time-dependent variation in weight and body composition in healthy adults.
abstract: OBJECTIVE
  To define the limits of change in body weight and body composition after different time intervals in healthy, normal adults.
  
  
  METHODS
  Prospective and retrospective analyses of paired body composition studies in a total of 326 healthy adults, ages 18 to 97. Measurements included body weight, fat and fat-free mass (FFM) by dual x-ray absorptiometry (DXA) and bioimpedance analysis (BIA), plus body cell mass (BCM) by whole-body counting of 40K and BIA.
  
  
  RESULTS
  Time interval between studies was a significant predictor of the differences in paired studies. The 95% confidence intervals for percent difference were lowest for body weight, intermediate for BCM and FFM, and highest for fat, in part because of the differences in sizes of these body compartments. There were significant associations among the changes in body composition by BIA and by criterion methods, suggesting that the observed changes are real.
  
  
  CONCLUSIONS
  The normal variation in body weight and body composition increases over time. Time-dependent criteria may increase the sensitivity in diagnosing malnutrition. Interpreting changes in body compartments requires consideration of the size of each compartment.
authors.affiliation: Department of Medicine, St. Luke's-Roosevelt Hospital Center, College of Physicians and Surgeons, Columbia University, New York, New York 10025, USA.
authors.forename: K
authors.initials: K
authors.lastname: Rosenbaum
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: R N
authors.initials: RN
authors.lastname: Pierson
authors.forename: D P
authors.initials: DP
authors.lastname: Kotler
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001823:Body Composition; D001835:Body Weight; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012044:Regression Analysis; D012189:Retrospective Studies; D013997:Time Factors