Does caffeine make us have more energy even though it doesn’t have many calories? Does it make our bodies use up fat that is already stored? Where does the extra energy from caffeine come from?
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Your cells run on an energy source called ATP. After they use up the energy, adenosine from the molecule can ‘dock’ in receptors in your brain. This tells the brain to slow down, rest and recharge. Caffeine blocks these receptors without actually triggering them, thus you don’t feel sleepy.
Your brain overcomes this by making more receptors, hence adapting to caffeine consumption and needing more. It also explains the headaches and withdrawal symptoms experienced if you go a day or two without it; the extra receptors are removed over time and the symptoms fade.
Your sensation of “energy” from having slept well or drinking coffee isn’t actually related to the concept of “energy” in physics. Feeling less tired can’t be converted directly into a driving force for chemical reactions that form unfavorable chemical bonds. You can’t turn gasoline, oxygen, and a tired person into carbon dioxide, water vapor, and a non-tired person.
Energy in physics can’t be created or destroyed, so you can have great fun tracking where it came from and where it went. The sensation you call “energy” can be created and destroyed, so it doesn’t have to have come from anywhere.
Is it the same way amphetamines etc work?
There are…so many wrong answers here. With so many science types that pursue this subreddit, I am shocked.
Anyway, caffeine does a lot of what you read here, but the one that mentioned competitive binding of adenosine receptors was the most correct in terms of wakefulness. In purely ELI5 terms, it keeps a switch on that lack of ATP (intracellular batteries) would usually cause to flip off or at least make harder to actuate (thresholds) giving the sense of energy that is not chemically supported.
It also has an effect on the heart, smooth muscle, and skeletal muscles. Again, in simplest terms, causes your muscle lining in your trachea (breathing tube head – lungs) to relax, stimulated your heart, and constricts your blood vessels. Will this make you feel more energetic? Probs not. But as a caffiholic, when I overdo the coffee and diet Mountain Dew, I definitely feel my heart, lol.
Yes to previous posts about adrenaline etc. Also a pro tip, wait 2-3 hours after you wake up and eat breakfast to drink coffee. It prevents caffeine crash later in the day
It doesn’t give you literal energy in the sense of actual chemical energy, it gives you figurative energy in the sense that it makes you feel less fatigued. It accomplishes this by blocking receptors in the brain that normally give the sensation of fatigue when activated.
Caffeine basically puts tape over the “I’m tired” button.
This is why caffeine shouldn’t ever be used as a replacement for sleep. If you’re too tired to drive you’re too tired to drive, no matter how much coffee you’ve had
There are receptors in your body that are like buckets. These buckets, fill with water as you get tired, weighing you down. caffeine just acts as a temporary lid for these buckets. The water then waits until the lid (caffeine) is gone, and it rushes in. That’s why you get that caffeine crash.
I really liked this video that showed what was actually happening in simple graphics.
[How does caffeine keep us awake?](https://www.youtube.com/watch?v=foLf5Bi9qXs)
So caffeine fits well enough in your adenosine receptors that it blocks them. Your body freaks out a little bit from this and boosts Dopamine and Adrenaline production which is where the “extra” energy comes from. However your body never stops producing Adenosine which is the hormone (or chemical I can’t remember) that tells your body it’s tired, so when the caffeine stops blocking those receptors you get the sudden rush of tired that colloquially is referred to as “The Crash”. So caffeine doesn’t necessarily give you more energy it just makes you feel more alert and happy through trickery.
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