TY - JOUR
T1 - Relationship of resting metabolic rate to body composition and protein turnover
AU - Welle, S.
AU - Nair, K. S.
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 1990
Y1 - 1990
N2 - This study examined whether variability among healthy young adults in resting metabolic rate, normalized for the amount of metabolically active tissue (assessed by total body potassium), is related to protein turnover. Resting metabolic rate was measured by indirect calorimetry for 2 h in 26 men and 21 women, 19-33 yr old, with simultaneous estimation of protein turnover during a 4-h infusion of L-[1-13C]leucine. After adjusting metabolic rate for total body potassium, the standard deviation was only 89 kcal/day, or 5.5% of the average value. There was a high correlation between leucine flux (an index of proteolysis) and metabolic rate (r = 0.84) and between the nonoxidized portion of leucine flux (an index of protein synthesis) and metabolic rate (r = 0.83). This relationship was weaker, but still significant, after adjusting leucine metabolism and metabolic rate for total body potassium (r = 0.36 for leucine flux vs. metabolic rate, r = 0.33 for nonoxidized portion of leucine flux vs. metabolic rate, P < 0.05). The regression analysis suggested that the contribution of protein turnover to resting metabolic rate was ~ 20% in an average subject. Metabolic rate and protein turnover were highest in the subjects with the greatest amount of body fat, even after accounting for differences in whole body potassium. Neither resting metabolic rate nor protein turnover was related to total or free concentrations of thyroxine or triiodothyronine, within the euthyroid range. We conclude that 1) resting metabolic rate is quite homogeneous in healthy young adults after accounting for differences in body composition , 2) differences in protein turnover explain a small but significant fraction of the variability in resting metabolic rate, 3) increased body fat is associated with elevated metabolic rate and protein turnover.
AB - This study examined whether variability among healthy young adults in resting metabolic rate, normalized for the amount of metabolically active tissue (assessed by total body potassium), is related to protein turnover. Resting metabolic rate was measured by indirect calorimetry for 2 h in 26 men and 21 women, 19-33 yr old, with simultaneous estimation of protein turnover during a 4-h infusion of L-[1-13C]leucine. After adjusting metabolic rate for total body potassium, the standard deviation was only 89 kcal/day, or 5.5% of the average value. There was a high correlation between leucine flux (an index of proteolysis) and metabolic rate (r = 0.84) and between the nonoxidized portion of leucine flux (an index of protein synthesis) and metabolic rate (r = 0.83). This relationship was weaker, but still significant, after adjusting leucine metabolism and metabolic rate for total body potassium (r = 0.36 for leucine flux vs. metabolic rate, r = 0.33 for nonoxidized portion of leucine flux vs. metabolic rate, P < 0.05). The regression analysis suggested that the contribution of protein turnover to resting metabolic rate was ~ 20% in an average subject. Metabolic rate and protein turnover were highest in the subjects with the greatest amount of body fat, even after accounting for differences in whole body potassium. Neither resting metabolic rate nor protein turnover was related to total or free concentrations of thyroxine or triiodothyronine, within the euthyroid range. We conclude that 1) resting metabolic rate is quite homogeneous in healthy young adults after accounting for differences in body composition , 2) differences in protein turnover explain a small but significant fraction of the variability in resting metabolic rate, 3) increased body fat is associated with elevated metabolic rate and protein turnover.
KW - calorimetry
KW - leucine flux
KW - total body potassium
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U2 - 10.1152/ajpendo.1990.258.6.e990
DO - 10.1152/ajpendo.1990.258.6.e990
M3 - Article
C2 - 2360629
AN - SCOPUS:0025292876
SN - 0002-9513
VL - 258
SP - E990-E998
JO - American Journal of Physiology - Endocrinology and Metabolism
JF - American Journal of Physiology - Endocrinology and Metabolism
IS - 6 21-6
ER -