Caffeine is the world’s most widely used legal stimulant. It is a substance that occurs naturally in coffee, and in smaller quantities in tea. Energy drinks, cola and chocolate milk also contain caffeine. It is an interesting substance for strength athletes: caffeine promotes performance and increases fat burning.
1. Caffeine has a scientifically proven positive effect on (strength) sports performance. To take advantage of this, take 4-6 mg of caffeine per kg of body weight 45 to 60 minutes before your workout.
2. Caffeine also has a small stimulant effect on fat burning. To do this, take about 250 g per day. This can be done through farburners, but also through caffeine supplements or coffee.
3. Do not exceed 9 mg of caffeine per kg of body weight per day.
4. Contrary to what is often claimed, there is no habituation with caffeine supplementation with regard to enhanced sports performance. There is, however, a ceiling above which hardly any or no performance is promoted, while you may have to deal with negative side effects. That ceiling is around 6 mg/kg.
5. Supplements have only a small effect in strength sports and probably make no difference in the long term.
CAFFEINE AND STRENGTH PERFORMANCE
Caffeine has long been a popular substance among (strength) athletes, whether or not as part of their pre-workout supplement. Research shows that this is for good reason: caffeine promotes performance in both endurance and strength training [ xix ] .
Caffeine, for example, has a mildly stimulating effect on the central nervous system. As a result, most people experience a more energetic feeling and better focus [ i ] , more alertness [ ii ] and greater stamina [ xvii ] . The latter is not only beneficial for endurance athletes, but also for strength athletes [ iii ] .
It is striking that the use of caffeine has a strong placebo effect [ xxiii ] .
By far the best-researched strength sports supplement is creatine, followed by caffeine.
According to the same studies, to benefit from caffeine as a strength athlete, you have to ingest quite a bit. Doses of less than 3mg/kg of body weight (like a cup of coffee in the morning) can certainly improve wakefulness and alertness, but they are often not enough to get the job done when it comes to improving exercise performance.
Research showing performance benefits typically yields doses of 3-6 mg/kg, and most studies stay at the higher end of this range (5-6 mg/kg) just to be sure [ xxv ] . We keep it at 4-6 mg/kg body weight. The caffeine does not work immediately (see below) and you should therefore take it 45-60 minutes before training [ xxvi ] .
Caffeine is also a regular ingredient of pre-workout supplements. They often contain around 200 g of caffeine per serving, which is on the low side, based on the doses in the studies. However, there are also pre-workouts that provide around 300g of caffeine per serving. And of course you can take two servings at the same time if you wish.
Please note, this concerns the acute dose before training. In addition, there is a daily limit: according to the Nutrition Center an adult Dutch man ingests approximately 600 milligrams of caffeine per day, and a Dutch woman approximately 500 milligrams. Most healthy adults do not have any complaints [ xii ] .
The use of caffeine is often claimed to lead to a quick habituation, which is why you should always increase the dose. However, a 2022 meta-analysis, which included sixty studies, shows that frequent caffeine consumption, e.g. drinking coffee daily, does not negatively affect the performance-enhancing effects, regardless of whether it concerns strength or endurance sports [ xxi ] .
We have already seen that the dose-effect relationship (aka dose-response relationship ) is limited. After intake of about 6 mg/kg, there are no or hardly any higher effects, while more and more adverse effects can occur.
CAFFEINE AND FAT BURNING
Caffeine can actually speed up your metabolism (a little bit) [ viii ] . This is due to the already mentioned stimulating effect of caffeine on the nervous system, as well as on fat oxidation (the reaction of fat with oxygen) [ v ] . In addition , caffeine has a thermogenetic effect [ vi ] . Thermogenesis is the heat released in your body. And releasing that heat takes energy. A modest dose of 50 mg of caffeine alone increases heat production by the body by 6 percent for four hours after ingestion [ vii ]. In addition, caffeine ensures that more energy is obtained from stored fat instead of carbohydrates [ x ] .
Due to its beneficial effects on fat burning, caffeine is now the main ingredient in fat burners, where it was once the now banned ephedrine.
Fat burners contain an average of 250 g caffeine per daily dose. That is also the amount you can maintain if you take a caffeine supplement or coffee.
A single 100 mg dose increases the resting metabolic rate by 3 to 4 percent, while a 600 mg dose (spread over 12 hours) shows an 8 to 11 percent increase [ viii ] .
HOW MUCH CAFFEINE IS WISE?
Consuming caffeine is safe, provided it is done in moderation. What is too much varies greatly from person to person. Not everyone is equally sensitive to the effect of caffeine.
In general, 400 mg of caffeine is considered safe [ xi ] . But on average, the Dutch man consumes about 600 mg of caffeine per day, and the Dutch woman about 500 mg. And that usually presents no problems [ xii ] . Advice: do not take more than 9 mg of caffeine per kg of body weight per day.
If you regularly consume too much caffeine, you may experience restlessness, anxiety, irritability, headaches, tremors, dizziness, ringing in the ears and palpitations [ xvi ] .
Too much caffeine can also make it difficult to fall asleep [ xii ] . The half-life of caffeine is between 2.7 and 9.9 hours. For some, that means taking their last dose of caffeine early in the afternoon if they want to rule out negative effects on sleep [ xxviii ] .
HOW FAST DOES CAFFEINE WORK?
Many people think that caffeine exerts its stimulant effect almost immediately, i.e. within one or two minutes. Change that thought, because although coffee enters your bloodstream within minutes, it takes at least 10-15 minutes for you to notice the effect of a cup of coffee. Rather 30-90 minutes.
If you use caffeine to improve your performance, you better make sure that you have your cup(s) of coffee half an hour to an hour before the moment supreme. Ditto for a pre-workout or caffeine supplement. The aforementioned meta-studies on caffeine and strength performance conclude that 45-60 minutes before exercise is optimal.
FROM WHICH SOURCE?
In principle, it does not matter much from which source the caffeine comes to you. In this table you can see how much caffeine different food sources (coffee, tea, chocolate, chocolate milk, etc.) provide you. On average, a normal cup of coffee contains 90 to 150 mg of caffeine. A cup of green tea contains an average of 25 mg and black tea 42 mg. Since coffee without sugar is considered healthy [ xvi ] [ xvii ] , this seems to be the best and most efficient source of caffeine.
It is also a myth that caffeine from coffee works less well than caffeine in supplements.
Avoid caffeine from energy drinks: those are sugar bombs.
DOES SUPPLEMENTATION MAKE SENSE?
Whether you benefit from a caffeine supplement depends on your caffeine intake through regular food.
If you are a coffee lover and you drink five cups of coffee a day, then you are already at your maximum (and optimal) caffeine consumption. Keep this in mind if you also use a pre-workout supplement, for example. The popular NO-XPLODE 3.0 from BSN, for example, contains 300 mg of caffeine per serving. Then you can also drink two, at most three cups of coffee.
Do you want to use caffeine as a weight loss aid? Then you can also opt for a fat burner. In addition to caffeine and green tea extract, there are also some other ingredients that (possibly) contribute to fat burning and/or appetite reduction.
Caffeine has a scientifically proven positive effect on (strength) sports performance. To take advantage of this, you should take 4-6 mg/kg of body weight about 60 minutes before your workout.
Caffeine also has a small stimulant effect on fat burning. To do this, take about 250 g per day. This can be done through farburners, but also through caffeine supplements or coffee.
Contrary to what is often claimed, caffeine supplementation does not cause habituation with regard to enhanced performance. There is, however, a ceiling above which performance is no longer promoted, while you may have to deal with negative side effects. That ceiling is probably around 6 mg/kg.
Do not exceed 9 mg of caffeine per kg of body weight per day.
Coffee is a responsible source of caffeine, but you can also use caffeine or pre-workout supplements.
Fat burners also provide you with a lot of caffeine, but the added value of the other ingredients in these supplements is usually limited.
Supplements have only a small effect in strength sports and probably make no difference in the long term.
Published September 4, 2017, revised August 9, 2022.
- [i] https://www.ncbi.nlm.nih.gov/pubmed/16043199
- [ii] https://examine.com/rubric/effects/view/ecc35486a25550d252ac52256c6e22b8/5083fd00351203a9af3c78ab0163a4e9/all/
- [iii] https://www.ncbi.nlm.nih.gov/pubmed/20019636
- [iv] https://www.ncbi.nlm.nih.gov/pubmed/18046056
- [ v ] http://ajcn.nutrition.org/content/33/5/989.short
- [ vi ] http://ajcn.nutrition.org/content/51/5/759.short
- [vii] http://www.ergogenics.org/cafeine-meest-effectieve-afslanksupplement.html
- [viii] https://www.ncbi.nlm.nih.gov/pubmed/2912010
- [ix] https://www.ncbi.nlm.nih.gov/pubmed/7369170
- [x] https://www.researchgate.net/publication/245780297_Effects_of_Caffeine_Ingestion_on_Utilization_of_Muscle_Glycogen_and_Lipid_During_Leg_Ergometer_Cycling
- [xi] http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/caffeine/art-20045678
- [xii] http://www.voedingscentrum.nl/encyclopedie/cafeine.aspx
- [xiii] https://jissn.biomedcentral.com/articles/10.1186/1550-2783-7-18
- [xiv] https://www.extremetech.com/extreme/118369-how-to-optimize-your-caffeine-intake
- [xv] http://www.webmd.com/diet/features/healthier-ways-to-get-your-caffeine#1
- [xvi] http://www.voedingscentrum.nl/encyclopedie/koffie.aspx
- [xvii] https://www.ncbi.nlm.nih.gov/pubmed/28826374
- [xviii] https://www.youtube.com/watch?v=EDvtmmrubtM&t=421s
- [xix] https://examine.com/supplements/caffeine/
- [xx] https://link.springer.com/article/10.1007/s40279-018-0997-y
- [xxi] https://pubmed.ncbi.nlm.nih.gov/35536449/
- [xxii] https://examine.com/supplements/caffeine/#hem-power-output
- [xxiii] https://youtu.be/EDvtmmrubtM?t=650
- [xxiv] https://pubmed.ncbi.nlm.nih.gov/29527137/
- [xxv] https://www.strongerbyscience.com/caffeine/#Dose
- [xxvi] https://www.strongerbyscience.com/caffeine/#Timing
- [xxvii] https://pubmed.ncbi.nlm.nih.gov/30335479/
- [xxviii] https://pubmed.ncbi.nlm.nih.gov/6832208/