Prior exercise increases subsequent utilization of dietary fat.

Exercise appears to offer protection against weight gain, perhaps related to its effects on fat metabolism. Previous work in rats has shown that interventions resulting in a negative energy balance lead to alterations in the trafficking of dietary fat. This study was undertaken to determine whether exercise after an overnight fast would alter the partitioning of dietary fat between oxidation and storage. Seven female subjects (age = 26 +/- 1 yr, BMI = 21 +/- 1 kg x m(-2); mean +/- SEM) were recruited for three visits: rest, light, and heavy exercise. Stationary cycle exercise sessions were calculated to use 1,250 kJ and were done in a whole-body calorimeter. Dietary fat oxidation was calculated from the recovery of (13)C-oleate corrected for acetate sequestration and d(31)-palmitate given in a liquid meal 30 min after the completion of exercise. Cumulative oxidation of (13)C-oleate at 11.5 h postdose was significantly greater during the heavy exercise (49 +/- 4%) trial than both the light exercise (39 +/- 4%) and the rest trials (34 +/- 4%) (P < 0.005). Oxidation of d(31)-palmitate recovery at 11.5 h postdose was not different during the heavy exercise (12 +/- 1%), light exercise (11 +/- 1%), and rest trials (10 +/- 1%). These data illustrate that exercise has the ability to alter the trafficking of dietary fat. Furthermore, the effect of exercise is dependent on the type of fatty acid.