Smaller Organ Tissue Mass in the Elderly Fails to Explain Lower Resting Metabolic Rate

: We previously reported our in vivo prediction of whole body resting energy expenditure (REE) using magnetic resonance imaging and echocardiography‐derived organ volumes combined with published organ tissue metabolic rates.1 The models, developed in young healthy persons from predicted and measured...

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Bibliographic Details
Published in:Annals of the New York Academy of Sciences 2000-05, Vol.904 (1), p.449-455
Main Authors: GALLAGHER, DYMPNA, ALLEN, AARON, WANG, ZIMIAN, HEYMSFIELD, STEVEN B., KRASNOW, NORMAN
Format: Article
Language:English
Subjects:
Absorptiometry, Photon
Aged
Aged, 80 and over
Basal Metabolism
Body Composition
Body Height
Body Mass Index
Body Weight
Calorimetry
Echocardiography
Female
Humans
Magnetic Resonance Imaging
Male
Models, Biological
Organ Size
Potassium - analysis
Sex Characteristics
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Summary:: We previously reported our in vivo prediction of whole body resting energy expenditure (REE) using magnetic resonance imaging and echocardiography‐derived organ volumes combined with published organ tissue metabolic rates.1 The models, developed in young healthy persons from predicted and measured variables, were highly correlated (e.g., calculated vs. measured REE, r= 0.92, p < 0.001), with no significant differences (p= NS) between them. This study employed the same approach to determine whether possible age‐related decreases in organ tissue mass may account for the lower REE commonly reported in elderly persons. Measurements of REE (REEm) were acquired by indirect calorimetry. Calculated REE (REEc) models were developed from measured tissues and organs, and energy flux rates were assigned for each of the seven tissue/organ components, as reported by Elia.2 Older men (n= 6) and women (n= 7) had significantly lower REEm compared to REEc (p= 0.001). The magnitude of the differences were 13% and 9.5%, respectively, for men and women. These preliminary data suggest that factors other than organ atrophy may contribute to the lower metabolic rate of older persons. Further studies are required to investigate whether there is a reduction in the oxidative capacity of individual organs and tissues.
ISSN:0077-8923
1749-6632
DOI:10.1111/j.1749-6632.2000.tb06499.x