Caffeine has almost no calories, but it gives us energy. Where does this energy come from? Is caffeine making the body use its stored fat?
In: Chemistry
Caffeine doesn’t give us energy. It just blocks the signals from our body to our brain that tell us we’re tired.
Caffeine is not the “fuel” it’s a neuostimulant. You FEEL more energetic but it’s not that you are suddenly stronger/faster or whatever, just that it gets your brain doing stuff.
Caffeine doesn’t give you energy in a science sense. It affects the your brain works to make you feel more alert. There’s a chemical that builds up in our brain, making us tired. When you sleep, it goes back down and you feel more alert. Caffeine stops this chemical from building up so you don’t feel tired.
It’s like the difference between surgery and painkillers. You don’t get new energy, but you *feel* like you do just enough to get stuff done.
Caffeine gives you no real energy it just delays feeling tired by blocking receptors in your brain.
*Edit* I realised the way I worded this sounded a bit negative about caffeine. Caffeine is great I am personally a huge caffeine addict and quite frankly it not having calories is a benefit not a flaw, just because it doesn’t give you real energy doesn’t make the fact that it makes you feel more energetic any less valuable in the real world.
Caffeine does two main things. The primary thing it does is bind to adenosine receptors. Adenosine is something that the body produces while awake that helps signal when it’s time to sleep. By blocking this signal we feel less sleepy(at least, the kind of sleepy from adenosine, there are likely other things that make us feel tired as well) and that seems like we have more energy.
A second effect of caffeine is it mildly boosts epinephrine, aka adrenaline. This neurotransmitter drives focus and alertness. So not only do you have less “sleepy” chemical in your brain, you also have more “alert/attentive” chemicals in your brain.
Lastly, and it’s more of a minor effect as far as we know, there are generally other stimulative effects of caffeine consumption that do not work on the brain directly but on the gut, and it’s poorly understood what effect stimulants have on the gut and then, due to the nerves that connect the gut to the brain, may have further effects.
“I need energy” translates into one of two things: “I need to eat” (actual calories, energy in the physics sense), and “I need to sleep” (brain needs to do some house cleaning). As you say, caffeine has no calories to speak of, and does nothing for your “I need to eat” energy. What it actually does is allow you to ignore the “I need to sleep” signals your brain/body is generating.
Basically, some parts of your brain can produce [GABA](https://en.wikipedia.org/wiki/%CE%93-Aminobutyric_acid), which is sort of the “slow down” chemical of the brain. Caffeine acts by stopping the rest of the brain from receiving that GABA, so they never get the message to slow down.
It doesn’t give you energy it stimulates your nervous system and makes your body feel like it’s in danger so it focuses better.
From [Weaver’s Coffee](https://weaverscoffee.com/blogs/blog/how-caffeine-in-coffee-works):
>When caffeine enters the body, it is broken down into three different molecules: theobromine, paraxanthine, and theophylline. Each of these molecules has its own unique effect on the body.
>Theobromine increases oxygen and nutrient flow to the brain. Paraxanthine enhances athletic performance by increasing the rate of fat breakdown. Theophylline increases heart rate and concentration.
>Caffeine also blocks the effects of adenosine, a neurotransmitter that makes us feel tired. This is why caffeine can give us a boost of energy.
Caffeine does not provide energy. It suppresses the chemical that makes you feel tired while stimulating other bodily systems that make you (feel) energetic. If you lacked calories before a cup of unsweetened black coffee, you won’t have any after it either.
People are getting different mechanisms confused and mixed up.
Caffeine stimulates dopamine and adrenaline, which makes you more alert and that’s why you feel like you have more “energy”. The actual energy would come from stored glycogen reserves and fat reserves if required.
>The accumulation of cAMP then stimulates the release of hormones such as dopamine, epinephrine, and noepinephrine.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8202818/
Everyone else is mixing this up with the fact caffeine can delay sleep by blocking adenosine receptors, but that’s a seperate mechanism and something completely different.
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