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Metabolism. 2013 Jun;62(6):793-800. doi: 10.1016/j.metabol.2012.12.008. Epub 2013 Jan 11.

Effects of post-absorptive and postprandial exercise on 24 h fat oxidation.

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Doctoral Program in Sports Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, Japan 305-8574.



Fat oxidation during exercise depends on nutritional state, and exercise performed in the post-absorptive state oxidizes more fat than that performed in the postprandial state. However, the effects of exercise on energy metabolism continue during the post-exercise period, and the difference in fat oxidation during exercise may be compensated for during the post-exercise period. The present study compared the effects of an acute exercise bout in the post-absorptive or postprandial state on 24 h fat oxidation.


Twelve young male athletes stayed twice in a room-size metabolic chamber for 24 h indirect calorimetry in a randomized repeated-measure design. Before or after breakfast, i.e. in the post-absorptive or postprandial state, subjects exercised at 50% VO(2)max for 60 min.


During the 60 min of exercise, energy expenditure in the two exercise trials were equivalent, but exercise in the post-absorptive state was performed with lower RQ compared with that in the postprandial state (P<0.01). The time of exercise relative to breakfast did not affect 24 h energy expenditure (P>0.5). However, accumulated 24 h fat oxidation was higher (P<0.05) and that of carbohydrate oxidation was lower (P<0.05) when exercise was performed in the post-absorptive state.


Compared with exercise performed in the postprandial state, exercise performed in the post-absorptive state oxidized more fat and saved more carbohydrate in the body, without affecting 24 h energy expenditure.

[Indexed for MEDLINE]

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