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?

Question

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

Answer 1

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.