A Calorie is a unit of measure of energy.
Calories are how we measure the energy in food.
Food contains a chemical energy store. Chemical energy is also found in fuels and batteries.
When you wake up you have been sleeping for 8 hours — your body has been fasting. You wake up with your chemical energy store low. Having breakfast fills up your chemical energy store. As you go about your day you are using your chemical energy store and it depletes. Lunch time arrives and you can fill up your energy store again with that sandwich.
A 2 calorie iced coffee may appear to give you energy — but it barely contains calories. How does that work?
Although caffeine can be found in drinks such as coffee — caffeine itself does not contain chemical energy. Caffeine is a stimulant which helps your body release your stored energy. Caffeine increases your metabolic rate, which means the amount of calories burned.
How does caffeine do this?
Caffeine is a chemical which imitates the neurotransmitter adenosine in your brain.
Caffeine taking the place of adenosine
Do you recognise that feeling of sleepiness when going about your day? That’s adenosine attaching to receptors in your brain. When caffeine is in your system, it attaches to the brain’s receptors instead of sleep-inducing adenosine. This promotes feelings of alertness and focus as adenosine does not attach to receptors.
Caffeine is a stimulant which increases activity in the brain and nervous system
Your brain will adapt to the caffeine consumption. It will grow more receptors for the adenosine to attach. This results in a higher tolerance to caffeine, meaning you will need extra cups of coffee to get the same feelings of alertness and focus.
Adenosine still needs to do its job of powering down the brain.
Extra brain receptors grow for the adenosine to attach.
Beware of too much caffeine consumption. Although it is common to start the day, like any drug it should be used in moderation as too much may lead to anxiety, high blood pressure, insomnia and addiction. This is why if you stop drinking coffee you get feelings of withdrawal (tiredness, headaches, depressed moods). There are so many adeonsine receptors available and no need to fight over them with the absence of caffeine.
However in a few days your body will adjust as the extra adenosine receptors will disappear and you will as alert as ever.
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