Age-Dependent Changes in Resting Energy Expenditure (REE): Insights from Detailed Body Composition Analysis in Normal and Overweight Healthy Caucasians.
Age-related changes in organ and tissue masses may add to changes in the relationship between resting energy expenditure (REE) and fat free mass (FFM) in normal and overweight healthy Caucasians. Secondary analysis using cross-sectional data of 714 healthy normal and overweight Caucasian subjects (age 18-83 years) with comprehensive information on FFM, organ and tissue masses (as assessed by magnetic resonance imaging (MRI)), body density (as assessed by Air Displacement Plethysmography (ADP)) and hydration (as assessed by deuterium dilution (D₂O)) and REE (as assessed by indirect calorimetry). High metabolic rate organs (HMR) summarized brain, heart, liver and kidney masses. Ratios of HMR organs and muscle mass (MM) in relation to FFM were considered. REE was calculated (REEc) using organ and tissue masses times their specific metabolic rates. REE, FFM, specific metabolic rates, the REE-FFM relationship, HOMA, CRP, and thyroid hormone levels change with age. The age-related decrease in FFM explained 59.7% of decreases in REE. Mean residuals of the REE-FFM association were positive in young adults but became negative in older subjects. When compared to young adults, proportions of MM to FFM decreased with age, whereas contributions of liver and heart did not differ between age groups. HOMA, TSH and inflammation (plasma CRP-levels) explained 4.2%, 2.0% and 1.4% of the variance in the REE-FFM residuals, but age and plasma T3-levels had no effects. HMR to FFM and MM to FFM ratios together added 11.8% on to the variance of REE-FFM residuals. Differences between REE and REEc increased with age, suggesting age-related changes in specific metabolic rates of organs and tissues. This bias was partly explained by plasmaT3-levels. Age-related changes in REE are explained by (i) decreases in fat free mass; (ii) a decrease in the contributions of organ and muscle masses to FFM; and (iii) decreases in specific organ and tissue metabolic rates. Age-dependent changes in the REE-FFMassociation are explained by composition of FFM, inflammation and thyroid hormones.
Institute of Human Nutrition and Food Science, Christian-Albrechts-Universit&#228;t zu Kiel, D&#252;sternbrooker Weg 17-19, D-24105 Kiel, Germany. cgeisler@nutrfoodsc.uni-kiel.de.
Corinna
C
Geisler
Institute of Human Nutrition and Food Science, Christian-Albrechts-Universit&#228;t zu Kiel, D&#252;sternbrooker Weg 17-19, D-24105 Kiel, Germany. wbraun@nutrfoodsc.uni-kiel.de.
Wiebke
W
Braun
Institute of Human Nutrition and Food Science, Christian-Albrechts-Universit&#228;t zu Kiel, D&#252;sternbrooker Weg 17-19, D-24105 Kiel, Germany. mpourhassan@nutrfoodsc.uni-kiel.de.
Maryam
M
Pourhassan
Institute of Human Nutrition and Food Science, Christian-Albrechts-Universit&#228;t zu Kiel, D&#252;sternbrooker Weg 17-19, D-24105 Kiel, Germany. lschweitzer@nutrfoodsc.uni-kiel.de.
Lisa
L
Schweitzer
Clinic for Diagnostic Radiology, Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Am Botanischen Garten 14, D-24118 Kiel, Germany. glueer@rad.uni-kiel.de.
Claus-Christian
CC
Glüer
Institute of Nutritional Medicine, Universit&#228;t Hohenheim, Fruwirthstr. 12, D-70599 Stuttgart, Germany. Anja.Bosy-Westphal@uni-hohenheim.de.
Anja
A
Bosy-Westphal
Institute of Human Nutrition and Food Science, Christian-Albrechts-Universit&#228;t zu Kiel, D&#252;sternbrooker Weg 17-19, D-24105 Kiel, Germany. mmueller@nutrfoodsc.uni-kiel.de.
Manfred J
MJ
Müller
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D001481:Basal Metabolism / Q000502:physiology*; D001823:Body Composition / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D050177:Overweight / Q000378:metabolism*; D044465:White People; D055815:Young Adult
MRI; age; body composition; metabolic risk; resting energy expenditure