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, VO2max: 59.1±5.7 mL/kg/min) fasted (NoBK) or received breakfast (BK) and then ran for 60 minutes at 60% VO2max. 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