Effect of physical inactivity on the oxidation of saturated and monounsaturated dietary Fatty acids: results of a randomized trial.
OBJECTIVE
Changes in the way dietary fat is metabolized can be considered causative in obesity. The role of sedentary behavior in this defect has not been determined. We hypothesized that physical inactivity partitions dietary fats toward storage and that a resistance exercise training program mitigates storage.


METHODS
We used bed rest, with randomization to resistance training, as a model of physical inactivity.


METHODS
The trial took place at the Space Clinic (Toulouse, France).


METHODS
A total of 18 healthy male volunteers, of mean age +/- standard deviation 32.6 +/- 4.0 y and body mass index 23.6 +/- 0.7 kg/m(2), were enrolled.


METHODS
An initial 15 d of baseline data collection were followed by 3 mo of strict bed-rest alone (control group, n = 9) or with the addition of supine resistance exercise training every 3 d (exercise group, n = 9).


METHODS
Oxidation of labeled [d(31)]palmitate (the main saturated fatty acid of human diet) and [1-(13)C]oleate (the main monounsaturated fatty acid), body composition, net substrate use, and plasma hormones and metabolites were measured.


RESULTS
Between-group comparisons showed that exercise training did not affect oxidation of both oleate (mean difference 5.6%; 95% confidence interval [95% CI], -3.3% to 14.5%; p = 0.20) and palmitate (mean difference -0.2%; 95% CI, -4.1% to 3.6%; p = 0.89). Within-group comparisons, however, showed that inactivity changed oxidation of palmitate in the control group by -11.0% (95% CI, -19.0% to -2.9%; p = 0.01) and in the exercise group by -11.3% (95% CI, -18.4% to -4.2%; p = 0.008). In contrast, bed rest did not significantly affect oleate oxidation within groups. In the control group, the mean difference in oleate oxidation was 3.2% (95% CI, -4.2% to 10.5%; p = 0.34) and 6.8% (95% CI, -1.2% to 14.7%; p = 0.08) in the exercise group.


CONCLUSIONS
Independent of changes in energy balance (intake and/or output), physical inactivity decreased the oxidation of saturated but not monounsaturated dietary fat. The effect is apparently not compensated by resistance exercise training. These results suggest that Mediterranean diets should be recommended in sedentary subjects and recumbent patients.
Bergouignan
Audrey
A
Institut Pluridisciplinaire Hubert Curien, Département d'Ecologie, Physiologie, et Ethologie, Strasbourg, France.
Schoeller
Dale A
DA
Normand
Sylvie
S
Gauquelin-Koch
Guillemette
G
Laville
Martine
M
Shriver
Timothy
T
Desage
Michel
M
Le Maho
Yvon
Y
Ohshima
Hiroshi
H
Gharib
Claude
C
Blanc
Stéphane
S