title: Effects of post-absorptive and postprandial exercise on 24 h fat oxidation.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors: Doctoral Program in Sports Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, Japan 305-8574.
authors: Kenshiro
authors: K
authors: Shimada
authors: Yuki
authors: Y
authors: Yamamoto
authors: Kaito
authors: K
authors: Iwayama
authors: Kazuteru
authors: K
authors: Nakamura
authors: Sachiko
authors: S
authors: Yamaguchi
authors: Masanobu
authors: M
authors: Hibi
authors: Yoshiharu
authors: Y
authors: Nabekura
authors: Kumpei
authors: K
authors: Tokuyama
mesh_terms: D002149:Energy Intake; D004734:Energy Metabolism; D015444:Exercise; D005223:Fats / Q000378:metabolism*; D006801:Humans; D008297:Male; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D019518:Postprandial Period; D055815:Young Adult
chemical_list: D005223:Fats