Caffeine and Fat Burning

Do you drink coffee? More importantly, do you use coffee to help with your training or performance?

I know there are some people that can't touch the stuff before training or it results in a trip to the bathroom mid-workout. Personally, I love to sip on a cup of coffee for an early morning workout for a bit of a boost.

But does it help? Specifically with respect to fat burning, does caffeine help? And does it make a difference what time of day you have a cup of coffee in relation to your training?

A recent study looked to answer this question. They wanted to know if caffeine would boost fat burning.

What they did was have the experiment subjects have a drink 30 minutes before an aerobic exercise workout. The subjects included 15 males averaging 32 years old. The subjects did 4 sessions 7 days apart. This allowed them to experience all 4 test conditions of coffee, placebo, 8 AM training or 5 PM training.

The researchers controlled for fasting, exercise and other stimulants consumed. They wanted to make sure the subjects weren't doing workouts before coming to the lab or slamming back a Red Bull either.

The researchers used indirect calorimetry to measure maximal fat oxidation (MFO).

So what did they find?

MFO and VO2max were greater in the PM than in the AM.

When the groups consumed caffeine there was 10.7% greater MFO in the morning (i.e. 8 AM) compared to the group that consumed a placebo. And with the 5 PM group MFO was 29% greater when caffeine was consumed instead of a placebo.

So the two big takeaways are that:

1. Caffeine works and helps increase MFO
2. Results were better with the afternoon versus the morning group

A few things to keep in mind include:

• Would we see the same results for different ages rather than everyone of approximately 32 years?
• Would we see the same results for women?
• Would we see the same results for sedentary individuals? All the participants in this study were already active.
• Would the results have differed if more caffeine was consumed? The subjects consumed 3 mg/kg bodyweight. So an 80 kg individual would ingest 240 milligrams of caffeine. (a cup of coffee has about 100 mg)

Lastly, don't lose sight of the fact that the best time to exercise is when you can make time for it. Different chronotypes do better at different times of day. And although afternoon caffeine resulted in more MFO compared to the morning don't forget of the fat burning powers of sleep. If an afternoon cup of coffee disrupts sleep it may not be worth it.

Ramírez-Maldonado, M., Jurado-Fasoli, L., Del Coso, J., Ruiz, J. R., & Amaro-Gahete, F. J. (2021). Caffeine increases maximal fat oxidation during a graded exercise test: is there a diurnal variation?. Journal of the International Society of Sports Nutrition, 18(1), 1-9.