One study investigated whether caffeine consumption could increase the maximal rate of fat oxidation and cardiorespiratory capacity during exercise. And if so, whether or not this positive effect varied throughout the day.

Strong, coffee, 30, minutes, before, exercise, increases, fat, burning

Here is a little tip given by researchers from the University of Granada (Spain) to boost the efficiency of your sports session. In their recent study, published in the "Journal of the International Society of Sports Nutrition", the scientists showed that caffeine (about 3 mg/kg, the equivalent of a strong coffee) ingested half an hour before aerobic type physical exercise (activity that focuses on heart rate and breathing capacity) significantly increases the rate of fat burning. They also found that if this exercise is done in the afternoon, the effects of caffeine are more pronounced than in the morning.

Specifically, the researchers wanted to determine whether caffeine, one of the most widely consumed ergogenic (muscle-enhancing) substances in the world to improve athletic performance, actually increases the oxidation or "burning" of fat during exercise. Although its consumption in supplement form is very common, scientific evidence for its beneficial claims is scarce. "The recommendation to exercise on an empty stomach in the morning to increase fat oxidation is common. But it may lack a scientific basis. ", explains the lead author of this research, Francisco José Amaro-Gahete.

An impact regardless of the time of day but...

Indeed, "we do not know if this increase is due to exercise in the morning or to the deprivation of food for a long period. ", adds the scientist. To do this, the team asked 15 men with an average age of 32 to perform an exercise test four times over a 7-day period. Participants ingested 3 mg/kg of caffeine or a placebo at 8 a.m. and 5 p.m., and each completed the tests under the four conditions in a random order. The preconditions for each exercise test were the same for all: hours since last meal, exercise, or consumption of stimulant substances, and fat oxidation during exercise was calculated accordingly.

"The results of our study showed that acute ingestion of caffeine 30 minutes before performing an aerobic exercise test increased maximal fat (lipid) oxidation during exercise regardless of the time of day," adds Prof. Francisco J. Amaro, stating that "the existence of a diurnal variation in fat oxidation during exercise was confirmed, with higher values in the afternoon than in the morning for equal hours of fasting. "Furthermore, these results also show that caffeine increases fat oxidation during morning exercise in a manner similar to that observed without caffeine consumption in the afternoon. 

In summary, the study suggests that the combination of acute caffeine intake and aerobic type exercise performed at moderate intensity in the afternoon provides the optimal scenario for individuals seeking to increase fat burning during their sport. However, be careful to respect the health recommendations in terms of caffeine consumption. On this subject, the Anses recommends to prefer drinks containing natural caffeine (tea, coffee) to artificially enriched drinks (energy drinks...) and advises against coffee for people with certain pathologies (cardiovascular disorders, renal insufficiency, severe liver diseases...).