title: Resting metabolic rate in old-old women with and without frailty: variability and estimation of energy requirements.
abstract: OBJECTIVE
  To measure resting metabolic rate (RMR) in old-old adults living in the community and examine the association between measured RMR and frailty status and compare it with expected RMR generated by a predictive equation.
  
  
  METHODS
  Physiological substudy conducted as a home visit within an observational cohort study.
  
  
  METHODS
  Baltimore City and County, Maryland.
  
  
  METHODS
  Seventy-seven women aged 83 to 93 enrolled in the Women's Health and Aging Study II.
  
  
  METHODS
  Resting metabolic rate with indirect calorimetry, frailty status, fat-free mass, ambient and body temperature, expected RMR according to the Mifflin-St. Jeor equation.
  
  
  RESULTS
  Average RMR was 1,119 ± 205 kcal/d (range 595-1,560 kcal/d). Agreement between observed and expected RMR was biased and poor (between-subject coefficient of variation 38.0%, 95% confidence interval = 35.1-40.8). Variability of RMR was greater in frail individuals (heteroscedasticity F-test P = .02). Low and high RMR were associated with being frail (odds ratio 5.4, P = .04) and slower self-selected walking speed (P < .001) after adjustment for covariates.
  
  
  CONCLUSIONS
  Equations to predict RMR that are not validated in old-old adults appear to correlate poorly with measured RMR. RMR is highly variable in old-old women, with deviations from the mean predicting clinical frailty. These exploratory findings suggest a pathway to clinical frailty through high or low RMR.
authors.affiliation: Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21224, USA. cweiss9@jhmi.edu
authors.forename: Carlos O
authors.initials: CO
authors.lastname: Weiss
authors.forename: Anne R
authors.initials: AR
authors.lastname: Cappola
authors.forename: Ravi
authors.initials: R
authors.lastname: Varadhan
authors.forename: Linda P
authors.initials: LP
authors.lastname: Fried
mesh_terms: D000369:Aged, 80 and over; D001481:Basal Metabolism / Q000502:physiology*; D002153:Calorimetry, Indirect; D004185:Disability Evaluation; D002149:Energy Intake; D005260:Female; D016330:Frail Elderly; D015577:Geriatric Assessment; D006801:Humans; D008137:Longitudinal Studies; D008396:Maryland; D012044:Regression Analysis; D016138:Walking / Q000502:physiology