title: Comparison of methods for achieving 24-hour energy balance in a whole-room indirect calorimeter.
abstract: OBJECTIVE
  To evaluate and compare methods for achieving 24-hour energy balance in a whole-room indirect calorimeter.
  
  
  METHODS
  Twenty-four-hour energy expenditure (EE) for 34 healthy adults (16 women, 18 men) was measured in a calorimeter during a prestudy day and on a subsequent nonconsecutive assessment day (AD). Several methods for estimating EE on the AD using activity factors or regression equations with data available before the AD [anthropometrics, body composition, resting metabolic rate (RMR), sleeping metabolic rate (SMR) on prestudy day, 24-hour EE on prestudy day] were compared for predictive accuracy.
  
  
  RESULTS
  Use of a 24-hour calorimeter stay gave the smallest mean absolute error (119 +/- 16 kcal/d) and smallest single maximum error (361 kcal/d). However, several other methods were only slightly, and not significantly, less accurate (e.g., mean absolute error = 131 +/- 17, 140 +/- 20, and 141 +/- 22 kcal/d and greatest error = 384, 370, and 593 kcal/d for anthropometric, RMR, and SMR regression equations, respectively). Fat-free mass alone and SMR with a simple activity factor were seen to be less accurate.
  
  
  CONCLUSIONS
  Our results indicate that there may be some improvement in achieving 24-hour energy balance in a metabolic chamber by using a preceding 24-hour calorimeter stay; that only slightly less accurate predictions can be obtained using a combination of anthropometric, body composition, and/or RMR measurements; and that there is little or no advantage in using SMR from a previous overnight calorimeter stay.
authors.affiliation: Department of Preventive Medicine and Biometrics, University of Colorado Health Sciences Center, Denver Colorado 80262, USA. Gary.Grunwald@uchsc.edu
authors.forename: Gary K
authors.initials: GK
authors.lastname: Grunwald
authors.forename: Edward L
authors.initials: EL
authors.lastname: Melanson
authors.forename: Jeri E
authors.initials: JE
authors.lastname: Forster
authors.forename: Helen M
authors.initials: HM
authors.lastname: Seagle
authors.forename: Teresa A
authors.initials: TA
authors.lastname: Sharp
authors.forename: James O
authors.initials: JO
authors.lastname: Hill
mesh_terms: D000328:Adult; D001481:Basal Metabolism; D001823:Body Composition; D002153:Calorimetry, Indirect; D004734:Energy Metabolism; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012890:Sleep / Q000502:physiology