ELI5- If calories are units of energy how does caffeine give you energy if it doesn’t contain calories?

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ELI5- If calories are units of energy how does caffeine give you energy if it doesn’t contain calories?

In: Chemistry

Caffeine affects insulin levels in your body and raises your blood sugar giving you more energy.

Different type of energy.

1. Ability to do work. Like potential and kinetic energy. Chemical energy stored in things like carbs, fats, and proteins. Or the chemical energy in wood that you burn in a fire place. The potential energy of a bowling ball getting dropped from a skyscraper.

2. Feeling “energized.” Awake. Stimulated. Primed.

Caffeine does not contain digestible energy. But it is a stimulant that makes you feel more awake.

Caffeine does not give you energy. Not even a little.

What it does is keep you from knowing that you are tired. You still are tired and you body still suffers the negative effects of it, but you can’t feel it anymore.

In addition if you drink too much caffeine too often, your body adjusts itself, so you only feel normal amounts of tired if you have caffeine in your system. If you don’t, like for example right after you wake up in the morning, you will find you are unable to fully awaken without caffeine.

Caffeine does not supply your body with chemical energy, it gives your body and brain the sensation of wakefulness. Caffeine blocks certain receptors that regulate how tired we feel, causing us to feel more energetic than we actually are. So while we might be so tired that we would normally want to lie down and stop moving, it tricks us into feeling like we have enough energy to do more active tasks.

By the way, you should use the search function here. This question was asked very recently.

Caffeine does not give you energy. It blocks need of sleep receptors in the brain.

Our normal sleep cycle is controlled by producing a neurotransmitter. That transmitter gets picked up by receptors. When enough receptors get the transmitter, you feel tiered. Sleep clears out the transmitter and you feel awake.

Caffeine clogs the receptors without triggering them. So no matter how much of the neurotransmitter you have you don’t feel sleepy.

Nothing to do with “energy”. Just tricking our brains into not applying the breaks.

Obviously the stuff I said above is oversimplified.

I feel like some of these answers kind of skirt around the answer a bit. Does caffeine give you energy? If you take it You’d probably say yes. Seems like that prompted the question. But, there’s a difference between the way we colloquially use the term “energy” and how we use it when referring to the physics concept energy that has units as you stated in the title.

A calorie is energy in the physics sense. We could measure food for calories, we could measure calories in a battery if we wanted to. When people drink caffeine and it gives them “energy” they’re just referring to the feeling of alertness and lack of tiredness and stimulation caffeine gives (it’s a pretty classic stimulant for humans biologically speaking). That’s absolutely true, and if you called that energy in a non scientific setting you wouldn’t be wrong. But I’m that’s not the same as the unit energy. The other answers here give great answers as far as physics energy is concerned. I just wanted to elaborate because some answers are a bit too rigid.

Caffeine has many effects on the body, all of which synergistic to giving you more “energy.”

The brain: Caffeine stimulates the methlyxanthine receptors which are involved in the focus/drive/alert feeling.

Cardiovascular: Here it mimics adenosine, which increases heart rate/blood pressure and overall cardiac functions. Adenosine is what you inject into someone who’s heart has stopped, to make it start again.

Metabolic: in high doses it increases fat mobilization which can indirectly help keep you fueled for activity.

Muscles: in high doses causes calcium leakage intra muscle which increases rate of force/power development.

Sidenote: the kcal is a unit of heat, not energy. When we burn fuel in the body we give off heat and thus the kcal is used as a proxy for actual energy consumption.

The energy we feel and the energy in the universe are not the same thing. The word energy is a very broadly used word and can mean different things depending upon what you’re talking about.

Your body stores calories like a car stores fuel. Caffeine makes the motor run faster but it’s not fuel in the tank.

Caffeine is a central nervous system stimulant. It doesn’t give you more energy per se, it makes you feel more energetic by speeding up your metabolism aka making your body burn more of the energy you have stored. Your body has stored energy already in forms such as fat and blood glucose.

Also coffee technically does contain like 2 calories haha, more if you add sugar.