Resting Metabolic Rate in Old-Old Women with and without Frailty: Variability and Estimation of Energy Requirements

Authors

  • Carlos O. Weiss MD, MHS,

    Corresponding author
    1. Department of Medicine, Saint Mary's Health Care/Advantage Health, Grand Rapids, Michigan
    2. Department of Family Medicine, College of Human Medicine, Michigan State University, Grand Rapids, Michigan
    • Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland
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  • Anne R. Cappola MD, ScM,

    1. Department of Medicine, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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  • Ravi Varadhan PhD,

    1. Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland
    2. Department of Biostatistics, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
    3. Center on Aging and Health, Johns Hopkins Medical Institutions, Baltimore, Maryland
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  • Linda P. Fried MD, MPH

    1. Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York
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  • [See Editorial Comments by Luigi Ferrucci, Jennifer A. Schrack, Nicolas D. Knuth, and Eleanor M. Simonsick on pp 1768–1769]

Address correspondence to Carlos O. Weiss, Mason F Lord, Center Tower, 7th floor, 5200 Eastern Ave, Baltimore, MD 21224. E-mail: cweiss9@jhmi.edu

Abstract

Objectives

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.

Design

Physiological substudy conducted as a home visit within an observational cohort study.

Setting

Baltimore City and County, Maryland.

Participants

Seventy-seven women aged 83 to 93 enrolled in the Women's Health and Aging Study II.

Measurements

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.

Conclusion

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.

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