Caffeine is a natural substance found in plants. It is found in coffee beans, tea, and cocoa beans. Caffeine as a pure substance is a white powder with a bitter taste and has a mild stimulant effect. A cup of coffee easily contains 40mg to 50 mg of caffeine. In tea, caffeine is often called theine, often a cup of tea contains 15mg to 20 mg of caffeine/theine. 


Caffeine is consumed regularly for a reason. It has a positive effect on physical and mental performance. Books have been written and countless scientific studies done to confirm these effects. For example, a dose of caffeine can significantly improve performance, focus and fat burning (ad1, ad2, ad3, ad4). 

It is even used by the US Special Forces to improve performance and alertness. These soldiers were tested extensively after long and strenuous exercises in the middle of the night. The soldiers absorbing caffeine via chewing gum performed much better than the control placebo group (ad2).


How does caffeine work?

Caffeine can be easily absorbed by the body. It is quickly absorbed into your bloodstream. Your blood levels peak after about 90 minutes if you take it via drinks, powder, or pills. However, the fastest absorption works through chewing gum, or energy gum. Absorbed through the mucous membranes in your mouth, it works within 10 minutes (ad6). Many people wonder how long it takes for caffeine to leave your body. Caffeine works for 3 to 5 hours and has a half-life of 6 hours, so it stays in your blood for quite a long time (ad7, ad8). Unlike most supplements, caffeine acts on cells throughout the body, including muscle cells and the brain. For this reason, there are many different effects that caffeine has on the body, these include:

  • The nervous system: Caffeine activates areas in the brain and nervous system to improve focus and energy, in addition, caffeine reduces fatigue (ad7, ad9).
  • Hormones: Epinephrine, also known as adrenaline, is the hormone responsible for the ""fight or flight"" response, which can increase performance (ad3)
  • Fat burning: Caffeine can increase the body's ability to burn fat via lipolysis or the breakdown of fat in fat cells (ad3).
  • Endorphins: β-endorphins can increase the feeling of well-being and can provide a ""high"" feeling, which people often experience after exercise (ad10, ad11).
  • Muscles: Caffeine can affect the motor cortex that designates a part of the brain to activate muscles (ad12).
  • Body temperature: Caffeine has proven increase thermogenesis or heat production, which causes you to burn more calories (ad13).
  • Glycogen: Caffeine can also conserve muscle glycogen stores, mainly as a result of increased fat burning. This can have a positive effect on endurance (ad14).

Caffeine is eventually broken down in the liver (ad7).


What does caffeine do to your body?

Elite athletes use caffeine in their diet or as a supplement for a reason. In elite sports, small details and hundredths of a second can make all the difference. Not only in games but also in daily training you have to ask the utmost of your body and mind. Caffeine has an effect on exactly these two components. It improves your performance, allowing you to sustain efforts longer but it also reduces your perception of effort. That is, the performance seems to feel less strenuous than it actually is. Pretty valuable to help you get over that low point when real fatigue starts to kick in.

So, it is evidenced that  caffeine causes significant improvements in the performance of endurance athletes. What about evidence in this area? In a study of cyclists, caffeine was shown to be superior to carbohydrates or water. The group with caffeine saw increased performance of 7.4% compared to 5.2% in the carbohydrate group. Another study combined caffeine and carbohydrates, which improved performance by 9% over water, and 4.6% over carbohydrates (ad16). In a study where subjects had to do a 1,500-meter run, regular coffee drinkers were 4.2 seconds faster than those who drank decaffeinated coffee. An important effect of caffeine also appears to be that it helps reduce the perception of exertion (ad17, ad18). So, you really can do more than you think with caffeine in your system.


Caffeine and strength exercises

One of the most commonly used ingredients in pre-workout supplements is caffeine. We know the scoops and pills that are supposed to make you go sky-high. In addition to its effects on endurance and focus, there is also an effect to help you lift the weights more powerfully.

A comparison of 27 different studies found that caffeine can improve leg muscle strength by up to 7%, but has no effect on smaller muscle groups (ad19). Caffeine can also improve muscle endurance, including the number of repetitions at a given weight (ad19).

Research continues on the use of caffeine in strength-based activities. Although several studies have found a positive effect (ad20, ad21), more research is certainly needed in this area.  


Caffeine and fat loss

The search for the perfect weight-loss tool is almost as old as the road to Rome, and caffeine is a common ingredient in weight-loss supplements. Now, there is no magic potion that will vaporize all the fat without any effort. The basics will always be healthy eating and good exercise, but don't completely forget the effects of caffeine in this story.

Caffeine can help release stored fat from fat cells, especially before and at the end of a workout. In addition, it can also help burn more calories. In fact, research has shown that taking caffeine before exercise increases the release of stored fat by as much as 30% (ad22). Another study showed that caffeine supplements increased the release of stored fat before and after a workout (ad22). Caffeine may also increase the amount of fat burned during exercise. In fact, caffeine increases heat production and adrenaline levels, which help burn extra calories and fat (ad3, ad14). Only at the moment there is no evidence that caffeine improves long-term weight loss, a good push it certainly is but the rest you really have to do yourself.


Ad1: Spriet et al. (1992) Caffeine ingestion and muscle metabolism during prolonged exercise in humans.

Ad2: McLellan et al. (2005) Caffeine maintains vigilance and improves run times during night operations for Special Forces.

Ad3: Graham et al. (1985) Metabolic, catecholamine, and exercise performance responses to various doses of caffeine.

Ad4: McLellan et al (2005) Caffeine maintains vigilance and marksmanship in simulated urban operations with sleep deprivation.

Ad5: Frary CD et al (2008) Food sources and intakes of caffeine in the diets of persons in the United States.

Ad6: Kamimore GH et al (2002) The rate of absorption and relative bioavailability of caffeine administered in chewing gum versus capsules to normal healthy volunteers.

Ad7: Fredholm BB et al (1999) Actions of caffeine in the brain with special reference to factors that contribute to its widespread use.

Ad8: Harland BF (2000) Caffeine and nutrition.

Ad9: Nehlig A et al (1992) Caffeine and the central nervous system: mechanisms of action, biochemical, metabolic and psychostimulant effects.

Ad10: Rogers NL et al (2005) Caffeine: implications for alertness in athletes.

Ad11: Lauren D et al (2000) Effects of caffeine on muscle glycogen utilization and the neuroendocrine axis during exercise.

Ad12: Kalmar Jm et al (1999) Effects of caffeine on neuromuscular function.

Ad13: Astrup A et al (1990) Caffeine: a double-blind, placebo-controlled study of its thermogenic, metabolic, and cardiovascular effects in healthy volunteers.

Ad14: Pedersen DJ et al (2008) High rates of muscle glycogen resynthesis after exhaustive exercise when carbohydrate is coingested with caffeine.

Ad15: Graham TE et al (1998) Metabolic and exercise endurance effects of coffee and caffeine ingestion.

Ad16: Hulston CJ, Jeukendrup AE (2008) Substrate metabolism and exercise performance with caffeine and carbohydrate intake.

Ad17: J D Wiles (1992) Effect of caffeinated coffee on running speed, respiratory factors, blood lactate and perceived exertion during 1500-m treadmill running.

Ad18: Demura S et al (2007) Effect of coffee ingestion on physiological responses and ratings of perceived exertion during submaximal endurance exercise.

Ad19: Warren GL et al (2010) Effect of caffeine ingestion on muscular strength and endurance: a meta-analysis.

Ad20: Beck TW et al (2006) The acute effects of a caffeine-containing supplement on strength, muscular endurance, and anaerobic capabilities.

Ad21: Astorino TA et al (2008) Effect of caffeine ingestion on one-repetition maximum muscular strength.

Ad22: Pasman WJ et al (1995) The effect of different dosages of caffeine on endurance performance time.

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