Caffeine 101

Caffeine 101


Caffeine is one of the most studied supplements available to us, and one which has undeniable benefits from a sports performance perspective. Caffeine is used as an ergogenic aid and research on dates back to 1907.

While caffeine exists naturally in coffee beans and tea leaves, it can also be extracted and synthesised. As such, caffeine can be found not only in tea and coffee, but in a range of products including energy drinks, sports supplements, and wakefulness pills (No-doz being a popular brand).

How It Works

In the brain, adenosine acts as an inhibitory neurotransmitter. Therefore, the stimulation of adenosine will act as a central nervous system depressant, meaning that when adenosine binds to its receptor in the brain your arousal will be limited.

Caffeine works as a stimulant by antagonising adenosine receptors, effectively “blocking” the adenosine from binding. The result is a sympathetic nervous system response which results in:

  • Increased heart rate
  • Increased adrenaline
  • Increased blood glucose
  • Increased blood pressure
  • Increased oxygen uptake

These acute physiological changes explain why caffeine is found to have performance benefits. While most of the early research focused on aerobic performance, more recent research has focused on muscular strength, muscular power, sports performance and cognitive/focus enhancement. Overall, the research has found that the above physiological effects from caffeine consumption translate to the following performance outcomes:

  • Increased muscular strength
  • Increased muscular power
  • Increased anaerobic running capacity
  • Increased aerobic exercise capacity
  • Increased reaction time
  • Increased wakefulness (decrease in drowsiness)
  • Increased fat oxidation
  • Increased memory recall
  • Appetite suppressant


Things to be Careful of

Responses in caffeine ingestion tend to have a high degree of inter-individual variability, and as such, individuals should play close attention to how they respond to caffeine ingestion (especially when it comes to timing and dosage). Key negative effects of caffeine consumption are as follows:

  • Increased anxiety
  • Increased tolerance to caffeine
  • Decrease sleep duration and quality

While the list of benefits seems on the surface to far outweigh the negatives, chronic poor sleep, due to continual caffeine use (or abuse), may contribute to all the negative effects which can arise from chronic lack of sleep — which is a serious list.

Chronic lack of sleep usually arises because of the effect caffeine has on the sympathetic nervous system, combined with its clearance rate from the body. Given that caffeine has a standard half-life of 4-6 hours, it is not uncommon for many to have large amounts of caffeine in their bloodstream after a day of heavy caffeine consumption. This can very easily lead to suboptimal sleep, producing brain fog and fatigue the next day

The solution that caffeine consumers commonly opt for is to simply consume more caffeine. This effectively band-aids the problem without addressing the root cause of their sub-optimal state.

In addition to this, many individuals claim that they do not feel the effect of caffeine, and that they often consume caffeine before sleep. This is not evidence of caffeine not having a physiological effect, but likely due to the individual’s inability to truly identify what constitutes a “good sleep.” This is common in individuals who are constantly in a heightened state of stress, usually due to lifestyle factors (such as high stress jobs). These individuals are also the ones who are likely to be consuming copious amounts of caffeine to help them “cope” with their stressful lifestyle. It will usually work for a time, but eventually the cost of high stress and poor sleep will catch up to them. We recommend you avoid this, if possible, though.

Conditions which have a high association with chronic poor sleep include:

  • Hypertension
  • Cardiac event (heart attack or stroke)
  • Weight gain and obesity
  • Diabetes
  • Depression and anxiety
  • Immune system deficiency
  • Decreased fertility (women)
  • Low testosterone (men)

While caffeine can be an incredibly effective ergogenic aid from a performance and cognitive perspective, it should be consumed mindfully and with respect. It is after all, a stimulating drug.


Role in Fat-burners

Fat-burners are very alluring supplements, as fat loss is one of the most desired outcomes of those that engage in physical activity. Unfortunately for most, though, fat-burners lack the potency to genuinely lead to a noticeable decrease in body-fat.

Fat-burners, theoretically, work in a way which is twofold. Potent fat-burners will be strong stimulants, therefore increasing metabolic rate (proportionate to the potency and dosage of the stimulant), while also having a strong suppressing effect on appetite (also proportionate to the potency and dosage of the stimulant). This marginal increase in “calories out” combined with a decrease in “calories in” (is hoped to) result in the same kind of fat-loss observed when using fat-loss drugs/medication.

However, due to the most potent fat-burners only being available upon prescription, caffeine usually becomes the drug of choice to put into a commercial fat burning supplement in order to suppress appetite and increase thermogenesis. While this may be used to great effect as a pre-workout, and somewhat as an appetite suppressant, an individual will almost always require some form of dietary caloric management as well to ensure they are eating in a caloric deficit.

The deficit is always the cause of the fat-loss, not the fat-burner. The fat-burner may assist in facilitating a caloric deficit, however.



Caffeine dosages need to be tailored according to the individual’s tolerance levels. If you are new to caffeine supplements, start with a 100mg dose. Typically, 200mg of caffeine is used for appetite suppressing purposes, while acute strength increases occur at higher doses (500mg and above). Researchers tend to use a dosage range of 4-6mg/kg bodyweight to induce performance improvements.


Credit Aaron Hoey