Research
Mixed
Caffeine intake of 6 mg/kg does not significantly alter total carbohydrate or fat oxidation rates during steady-state exercise, despite changing plasma metabolite profiles.
Don't worry about caffeine changing your body's fuel usage (fat vs. carbs) during exercise. The study shows it doesn't significantly change how much fat or carbs you burn. The performance boost likely comes from feeling less effort and better nervous system function, not from sparing glycogen.
GoodRefutesHIGH confidence
Similarly, there were no differences in instantaneous rates of CHO and fat oxidation, resulting from the different caffeine treatments, at any time point... Total CHO oxidation... did not differ according to treatment... Total fat oxidation... was also similar
Why this rating
Direct measurement of gas exchange and blood metabolites in a controlled setting.
Source
Effect of different protocols of caffeine intake on metabolism and endurance performance
Gregory R. Cox et al. · Journal of Applied Physiology · 2002
DOI 10.1152/japplphysiol.00249.2002
crossover · n=20Cited 308×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
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