Maximal fat oxidation at the different exercise intensity in obese and normal weight men in the morning and evening

Abstract

Introduction: Circadian rhythms regulate some metabolic and hormonal variables that affect fat oxidation rates. Thus, the purpose of this study was to investigate Maximal fat oxidation (MFO) at a different exercise intensity in obese and normal weight men in the morning and evening. Methods: MFO was measured in 12 normal weight (BMI 20-25 kg/m2; VO 2max 45.7±3.44 ml/min/kg) and 10 obese (BMI >30 kg/m2; VO 2max 37.2±3.6 ml/min/kg) men during incremental running exercise test with 3 min stages on the treadmill by indirect calorimetry method. Student's t-test and one-way ANOVA with repeated measures were used to analysis variables. Results: We found that fat oxidation rates and energy expenditure in both groups in the evening were higher than morning; there were no significant differences in MFO between obese and normal groups. Furthermore, the fat oxidation rate in low intensity exercise (<60% VO2max) was similar in obese and normal weight groups, but in high exercise intensities, in normal weight men were significantly higher than obese men. Conclusion: Our results suggest that independent of exercise intensity and body fat mass, exercising in the evening is more effective on fat oxidation and decrease body fat mass; therefore, it is better for weight loss purposes in obese and normal weight men.