Exercising in the Fasted State Reduced 24-Hour Energy Intake in Active Male Adults

The effect of fasting prior to morning exercise on 24-hour energy intake was examined using a randomized,counterbalanced design. participants (12 active,white males,20.8 � 3.0 years old,v o 2 m a x: 59.1 � 5.7 ml/kg/min) fasted (nobk) or received breakfast (bk) and then ran for 60 minutes at 60% v o 2 m a x. all food was weighed and measured for 24 hours. measures of blood glucose and hunger were collected at 5 time points. respiratory quotient (rq) was measured during exercise. generalized linear mixed models and paired sample t -tests examined differences between the conditions. total 24-hour (bk: 19172 � 4542 kj versus nobk: 15312 � 4513 kj; p < 0.001) and evening (bk: 12265 � 4278 kj versus nobk: 10833 � 4065; p = 0.039) energy intake and rq (bk: 0.90 � 0.03 versus nobk: 0.86 � 0.03; p < 0.001) were significantly higher in bk than nobk. blood glucose was significantly higher in bk than nobk before exercise (5.2 � 0.7 versus 4.5 � 0.6 mmol/l; p = 0.025). hunger was significantly lower for bk than nobk before exercise,after exercise,and before lunch. blood glucose and hunger were not associated with energy intake. fasting before morning exercise decreased 24-hour energy intake and increased fat oxidation during exercise. completing exercise in the morning in the fasted state may have implications for weight management. � 2016 jessica l. bachman et al.