More fuel for your caffeine habit: a new study shows that drinking coffee 30 minutes before a workout can significantly improve the amount of fat your body burns as you exercise.


Researchers at the University of Granada in Spain found that 3mg/kg of caffeine – roughly the equivalent of an eyeball-shaking espresso – increases the oxidation or 'burning' of fat during exercise.

In a small study of 15 men, they also found that the effects were stronger in the afternoon than they were in the morning.

"The recommendation to exercise on an empty stomach in the morning to increase fat oxidation is commonplace. However, this recommendation may be lacking a scientific basis, as it is unknown whether this increase is due to exercising in the morning or due to going without food for a longer period of time," said the lead author Francisco José Amaro-Gahete.

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In his study, participants completed an exercise test once a week for four weeks. After standardising other factors like time elapsed since their last meal or physical exercise, they ingested 3 mg/kg of caffeine or a placebo at 8am and 5pm before hopping on an exercise bike and completing a workout. Fat oxidation was then measured accordingly.

"The results of our study showed that acute caffeine ingestion 30 minutes before performing an aerobic exercise test increased maximum fat oxidation during exercise regardless of the time of day," said Amaro-Gahete. But the effect was stronger in the afternoon than the morning, offering anyone who's trying to shift a few lockdown pounds valuable new intel.

It's not the first time sports scientists have identified a cup of Joe as an everyday performance enhancer. Previous research has linked caffeine to improved endurance and alertness, and it's commonly used by athletes and military personnel, not to mention exhausted parents and deadline-chasing students.

With fat-burning, it's thought that caffeine raises your core body temperature, thereby increasing the number of calories you burn. It can also produce adrenaline and stimulate a process called lipolysis. This is the breakdown of adipose tissue (the fat we can pinch between our fingers) into fatty acids, which the the body can use as a source of energy.

Anyway, shall we pop the kettle on?

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A former deputy editor at Science Focus, Ian once undertook a scientific ranking of the UK's best rollercoasters on behalf of the magazine. He is now a freelance writer, which is frankly a lot less fun.