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Fyrius's avatar

Is there energy in caffeine?

Asked by Fyrius (14530points) June 7th, 2010

Caffeine wakes you up. But in what way?
Does consuming caffeine add energy to your system, like eating sugar does, or does it release energy that was already stored in there, like adrenaline does?

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9 Answers

marinelife's avatar

Caffeine affects your nervous system.

“Caffeine belongs to the xanthine chemical group. Adenosine is a xanthine that is naturally occurring in the brain, used as a neurotransmitter at some synapses. Because of their relation, caffeine looks a lot like adenosine to nerve cells and therefore binds to adenosine receptors in the basal forebrain. The cells then can no longer sense adenosine because caffeine is taking up the receptors. Instead of slowing down, the nerve cells speed up and stop the person from getting tired. ”

From University of Minnesota

ItsAHabit's avatar

Caffeine speeds metabolism and increases heart beat. It doesn’t contain energy but stimulates certain physiological activity and the effect is similar.

Fyrius's avatar

Oh wow, that’s amazing. So caffeine is just a filler material that blocks a natural body function that makes you tired?
I’m seeing transhumanist possibilities. Imagine if you could just decide to switch off adenosine reception for a moment, and get the same boost we get from coffee now.

I see. Thanks.

The main reason for this question, besides curiosity, is that I’ve been thinking about coffee and fitness. You can eat carbohydrates to get enough energy to do your workout, but if you can get the same energy from coffee, then you should be able to lose body fat faster, yes?
But nobody seems to do that. I wonder why not. There are so many people who drink coffee at least once every day, but use the energy for filling in forms or waking up in the morning.

ItsAHabit's avatar

I think you’re right. Incidentally, it’s wise to avoid alcoholic beverages that contain caffeine. They just mask the perception of intoxication.

nikipedia's avatar

@Fyrius: Some people do. Lots of people with eating disorders just replace food with coffee.

The problem is that food serves multiple purposes: besides just providing energy, it also provides other important nutrients and stabilizes your blood sugar.

My running partner and I recently had a long conversation about coffee before races. He claims that the physical boost you get from coffee is negligible and doesn’t really make a noticeable difference (otherwise runners would constantly be “doping” with caffeine), and since caffeine is a mild diuretic, the fitness boost you get from it is undermined by the decrease in hydration. I’m thinking it would not be difficult to do a little experiment on this… I’ll report back if I do.

Fyrius's avatar

Yes, naturally, coffee can’t be a substitute for proper food. For that matter there’s little point in working out at all without a steady supply of protein, unless you really only want to become skinny.
The context I was thinking of was rather that of having caffeine instead of energy drinks and other sugary stuff right before a workout.

I didn’t know about the dehydration issue. Noted. Thanks. Yes, for running (and general cardio, I suppose) I can see how that would be a problem.

Would there be similar problems with coffee before a weight lifting workout? Those can take a lot of energy too, but don’t make you lose as much water.

mattbrowne's avatar

Two issues here.

1) Caffeine is C8H10N4O2. Chemically there’s energy in it and we can get exothermic reactions out of it. Caffeine is metabolized through the liver.

2) Caffeine influences brain chemistry as described by @marinelife and makes people more energetic

Fyrius's avatar

I see. So there is some energy in it, even though that’s not what makes you feel energetic.

mattbrowne's avatar

@Fyrius – No, because the amount is far too small. What makes us energetic is this

and caffeine is merely an enabler removing tiredness from our brain.

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