Effect of caloric restriction with and without exercise on metabolic intermediates in nonobese men and women.
OBJECTIVE
The objective of the study was to evaluate whether serum concentrations of metabolic intermediates are related to adiposity and insulin sensitivity (Si) in overweight healthy subjects and compare changes in metabolic intermediates with similar weight loss achieved by diet only or diet plus exercise.


METHODS
This was a randomized controlled trial.


METHODS
The cross-sectional study included 46 (aged 36.8 ± 1.0 yr) overweight (body mass index 27.8 ± 0.7 kg/m(2)) subjects enrolled in a 6-month study of calorie restriction. To determine the effect of diet only or diet plus exercise on metabolic intermediates, 35 subjects were randomized to control (energy intake at 100% of energy requirements); CR (25% calorie restriction), or CR+EX: (12.5% CR plus 12.5% increase in energy expenditure by exercise).


METHODS
Serum concentrations of eight fatty acids, 15 amino acids, and 45 acylcarnitines (ACs) measured by targeted mass spectrometry.


RESULTS
In overweight subjects, the concentrations of C2 AC and long-chain ACs were positively associated with percent fat (R(2) = 0.75, P = 0.0001) and Si (R(2) = 0.12, P = 0.05). The percent fat (R(2) = 0.77, P < 0.0001), abdominal visceral fat (R(2) = 0.64, P < 0.0001), and intrahepatic fat (R(2) = 0.30, P = 0.0002) were positively associated with fatty acid concentrations. There was a significant increase in an AC factor (comprised of C2 and several medium chain ACs) in the CR group (P = 0.01).


CONCLUSIONS
In nonobese subjects, fasted serum ACs are associated with Si and fat mass. Despite similar weight loss, serum ACs increase with CR alone but not CR+EX. A greater improvement in Si with weight loss during CR+EX interventions may be related to improved coupling of β-oxidation and tricarboxylic acid cycle flux induced by exercise.
Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, Louisiana 70808, USA. leanne.redman@pbrc.edu
Leanne M
LM
Redman
Kim M
KM
Huffman
Lawrence R
LR
Landerman
Carl F
CF
Pieper
James R
JR
Bain
Michael J
MJ
Muehlbauer
Robert D
RD
Stevens
Brett R
BR
Wenner
Virginia B
VB
Kraus
Christopher B
CB
Newgard
William E
WE
Kraus
Eric
E
Ravussin
D050154:Adiposity / Q000502:physiology; D000328:Adult; D000375:Aging / Q000378:metabolism; D000596:Amino Acids / Q000097:blood; D001823:Body Composition / Q000502:physiology; D031204:Caloric Restriction; D002331:Carnitine / Q000031:analogs & derivatives / Q000097:blood; D003430:Cross-Sectional Studies; D003627:Data Interpretation, Statistical; D015444:Exercise / Q000502:physiology*; D005227:Fatty Acids / Q000097:blood; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D008660:Metabolism / Q000502:physiology*; D008875:Middle Aged; D050177:Overweight / Q000378:metabolism; D025341:Principal Component Analysis; D012727:Sex Characteristics; D013057:Spectrum Analysis; D015431:Weight Loss / Q000502:physiology
D000596:Amino Acids; D005227:Fatty Acids; C116917:acylcarnitine; D002331:Carnitine