TY - JOUR
T1 - Stimulation of protein turnover by carbohydrate overfeeding in men
AU - Welle, S.
AU - Matthews, D. E.
AU - Campbell, R. G.
AU - Nair, K. S.
N1 - Copyright:
Copyright 2004 Elsevier B.V., All rights reserved.
PY - 1989
Y1 - 1989
N2 - The effect of carbohydrate overfeeding on protein metabolism was studied in 11 healthy men. Total urinary nitrogen output during 10 days of carbohydrate overfeeding (1,600 extra kcal/day) decreased 27% relative to nitrogen excretion during 10 days of weight maintenance, indicating protein accretion during overfeeding. However, postabsorptive nitrogen excretion did not change, which means that the positive nitrogen balance associated with overfeeding results from enhanced postprandial nitrogen retention. Overfeeding reduced postabsorptive glucose concentrations 4 ± 1% and increased glucose production rate 14 ± 2% and glucose clearance 17 ± 4%. Overfeeding increased plasma concentrations of insulin, glucagon, and 3,5,3'-triiodothyronine ~20%. Alanine and branched-chain amino acid concentrations were increased after overfeeding, but serine, threonine, and asparagine concentrations were reduced. Postabsorptive leucine flux, which is an index of proteolysis, was measured using L-[1-13C]leucine as a tracer. Overfeeding increased leucine flux 13 ± 2% compared with values after 10 days on a weight-maintenance diet. If it is assumed that overfeeding did not alter the fraction of 13CO2 not recovered in breath, there was no change in the portion of leucine flux that was oxidized. Thus the difference between flux and oxidation, which is theoretical index of protein synthesis, increased 12 ± 3% after overfeeding. These data suggest that excess caloric intake, without an increase in protein intake, stimulates post-absorptive proteolysis and protein synthesis.
AB - The effect of carbohydrate overfeeding on protein metabolism was studied in 11 healthy men. Total urinary nitrogen output during 10 days of carbohydrate overfeeding (1,600 extra kcal/day) decreased 27% relative to nitrogen excretion during 10 days of weight maintenance, indicating protein accretion during overfeeding. However, postabsorptive nitrogen excretion did not change, which means that the positive nitrogen balance associated with overfeeding results from enhanced postprandial nitrogen retention. Overfeeding reduced postabsorptive glucose concentrations 4 ± 1% and increased glucose production rate 14 ± 2% and glucose clearance 17 ± 4%. Overfeeding increased plasma concentrations of insulin, glucagon, and 3,5,3'-triiodothyronine ~20%. Alanine and branched-chain amino acid concentrations were increased after overfeeding, but serine, threonine, and asparagine concentrations were reduced. Postabsorptive leucine flux, which is an index of proteolysis, was measured using L-[1-13C]leucine as a tracer. Overfeeding increased leucine flux 13 ± 2% compared with values after 10 days on a weight-maintenance diet. If it is assumed that overfeeding did not alter the fraction of 13CO2 not recovered in breath, there was no change in the portion of leucine flux that was oxidized. Thus the difference between flux and oxidation, which is theoretical index of protein synthesis, increased 12 ± 3% after overfeeding. These data suggest that excess caloric intake, without an increase in protein intake, stimulates post-absorptive proteolysis and protein synthesis.
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M3 - Article
C2 - 2782403
AN - SCOPUS:0024422770
VL - 257
SP - 20/3
JO - American Journal of Physiology
JF - American Journal of Physiology
SN - 0193-1849
IS - 3
ER -