Six Cups Of Coffee (900mg/day): Three Too Much or Just About Right to Speed Up Lipolysis & Fatty Acid Oxidation?

The human equivalent of almost 900mg caffeine per day used in the study at hand did some good, but it also did some harm - read more and decide for yourselves which one you'd consider more important.
It amazes me time and again. Coffee and caffeine in particular are unquestionably the best-researched "supplements", nutraceuticals, drugs, or whatever you want to call. Yet, nevertheless, the number of interesting studies is increasing day by day. Let's see... 2.3+ studies related to caffeine in one way or another were published per day in 2012 and as of now it looks, as if we would easily top that this year. But enough of those stats. Let's get to one of the latest of the 515 hits for this year and take a look at what Eun-Young Choi and Yun-Ok Cho from the Department of Food and Nutrition at the  Duksung Women's University in Seoul has to bring to the table.

What? Another rodent study?

Yeah, I hear you. I would also prefer if the Korean scientists had taken human subjects fed them a standardized diet and gave them water with 0.12 g freeze-dried instant coffee/100 g body weight for 4 weeks, but I hardly doubt the Ethics Committee would have approved of the guys and girls being sacrificed and their organs being harvested at the end of the 4-week period to check, whether or not the combination of coffee supplementation, which was combined with a chronic exercise (treadmills for 30 minutes; 5 d per week, 15° incline, 0.5-0.8 km/h; the dosage was chosen to approximate maximal quantity reportedly consumed by physically active individuals, i.e. 895 mg of caffeine/60 kg/d) regimen in 50% of the animals exerted independent (c) or combined effects on the organ weight liver as well as the liver and muscle glycogen content or not (data see figure 1).
 Figure 1: Effect of acute exercise, training (=chronic exercise) and chronic caffeine intake on heart, spleen, liver and visceral fat weight  (left), serum glucose and liver and muscle glycogen (Choi. 2013)
Luckily, it is quite unlikely that the overall effect of training + supplementation, of which you can see in figure 1 that only the former or a combination of both did have significant effects on heart weight, visceral fat and liver glycogen content, would have been fundamentally different, if the study had been conducted on human beings.
"The heart weights were significantly higher in the two training groups (TC, TCF) than the two control groups (NTC, NTCF). The combined visceral fat masses were significantly lower in the two training groups (TC, TCF) than the two non-training groups (NTC, NTCF). No significant effects on spleen and liver weights were being observed." (Choi. 2013)
As far as the caffeine or rather "simulated coffee consumption" is concerned, however, only the change in liver glycogen was affected. Particularly,
  • the chronically trained, caffeine guzzling rodents exhibited the higher liver glycogen levels (measured before acute exercise), while 
  • the animals in the non-trained caffeine guzzling group who had been sacrificed immediately after a final short bout of exercise at the end of the fourth week had the lowest liver glycogen concentration 
Overall, "coffee intake decreased liver glycogen levels in the T group, but no significant differences were observed" (Choi. 2013) in the non-trained animals. The muscle glycogen levels, on the other hand, were not significantly effected by caffeine intake. The 4 weeks of training, on the other hand induced a statistically significant increase in muscle glycogen (after rest) in the trained vs. untrained group of rodents - an observation that has previously been made in human studies, where chronic exercise in the presence of adequate carbohydrate nutrition will progressively increase the size of the muscular glycogen stores (supercompensation principle).

Similar to the increase in muscle glycogen during the 4-week training regimen, the observation that all training and/or supplementation regimen increased the amount of free fatty acids (FFA). What may come as a non-necessarily positive surprise to everyone with elevated baseline FFA levels, though is that addition of caffeine to the equation effectively doubled the training induced increase in resting FFA levels in the caffeine + training group. The beneficial effect of training on liver and muscle triglyceride levels, on the other hand, was not significantly impaired. And what many of you will probably deem about as important: caffeine did not affect the muscle, liver and plasma protein levels.

So what did the study find then?

If we summarize the above, the main findings of the study at hand were not exactly revolutionary, but there were some. Worth mentioning are ...
  1. Suggested read: "Coffee - The Good, The Bad & The Interesting: 2-4 Cups of Coffee for Adiponectin. Roasted Filtered Coffee & High LDL!? The Optimal Caffeine / Taurine Ratios & the Buzz ". Learn more about the good and bad sides of coffee / caffeine and find out whether taking taurine may buffer the side effects w/out compromising the benefits of exuberant amounts of caffeine, as they have been used in the study at hand? Or will it make things even worse? It certainly won't hurt the liver that's for sure (read more).
    an increase in free fatty acid release and usage during workouts (already well-established), which resulted in slightly more significant reductions in visceral fat, when training and caffeine were combined, 
  2. a highly desirable and significant reduction in liver fat in the trained rodents "on coffee" (all day), and a greater reduction in liver trigs in the animals that were only exercised once
  3. a more pronounced "in-and-out" of muscle triglycerides in the trained coffee guzzlers with significantly higher levels of muscle triglycerides before and significantly lower muscle triglyceride levels after a workout (probably a mechanism which contributes to the endurance boosting effects of caffeine; Sherman. 1995)
  4. a (surprising?) null-result for changes in plasma glucose that should put the "caffeine will give everyone diabetes" fears at rest; you should however remember that the FFA increase can generally become problematic overtime, if there is a concommittant influx of fatty acids from the diet and no fasting / exercise to keep the overall levels in check
  5. a significant reduction in glyocogen storage in the liver after a workout, of which I am yet not sure if this was not a result of a reduction in hepatic glycogen depletion due to the increase in fatty acid oxidation (the scientists do state that the training + caffeine group had the highest glycogen levels in the rested state)
  6. no effects on muscle glycogen or protein, and no effect on protein levels in other tissues due to caffeine
  7. a significant reduction in hematocrit in the coffee group the scientists ascribe to the hampered absorption of dietary iron
The overall image that emerges is thus rather a negative one - allegedly the increased visceral fat loss in nice, but it is not statistically significant compared to training alone (low iron = low oxygen carrying capacity = low performance; plus: low iron also hampers fatty acid oxidation so that even this benefit may be lost over time.

Another thing Alex Leaf, without even knowing it, reminded me about are the night-sweats and the 4AM wake up call, I know only too well from my own experience with copious amounts of stimulants. They could in fact be brought about by the inability to regenerate liver glycogen fast enough and the subsequent failure of providing your body with glucose from the liver while you sleep. This in turn will have you go hypoglycemic overnight. Your body reacts by spilling out stress hormones that will heat and wake you up...

Those three cups are probably as good as it gets, they protect your heart and can ward off cancer (learn more).
Bottom line: In view of the observed downsides, of which I would argue that (5) may actually be the worst for a healthy athlete, the study at hand appears to underline what I have told you before: the consumption of the equivalent of 800-900mg of caffeine per day is clearly counter-indicated even if you don't consume it all at once, and alongside its natural co-factors in coffee (learn more about coffee).

Stick to max. 400mg per day and you are more likely to get the benefits without the sides, about which you have read only a couple of days ago in a SuppVersity article discussing the acute ergogenic effects and accompanying side effects of different doses of caffeine (read more).

  • Sherman WM, Leenders N. Fat loading: the next magic bullet? Int J Sport Nutr. 1995 Jun;5 Suppl:S1-12. Review.
Disclaimer:The information provided on this website is for informational purposes only. It is by no means intended as professional medical advice. Do not use any of the agents or freely available dietary supplements mentioned on this website without further consultation with your medical practitioner.