PURPOSE: This study examined the acute effects of different caffeine doses on fat oxidation and cardiovascular responses at rest and during exercise at the intensity of maximal fat oxidation (FATmax) in overweight/obese sedentary female college students. METHODS: < 0.05. RESULTS: < 0.05). CONCLUSION: Acute caffeine intake at 3 and 5 mg/kg enhanced fat oxidation during FATmax exercise in sedentary overweight/obese females, whereas 9 mg/kg provided no additional metabolic benefit. However, the 5 mg/kg dose was associated with increased cardiovascular strain, which was not observed with the 3 mg/kg. Therefore, a dose of 3 mg/kg appears to offer an optimal balance between stimulating fat oxidation and maintaining cardiovascular safety in this population during acute exercise.
Gong et al. (Tue,) studied this question.