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 looks very much like adenosine. ( that’s the A in ATP which is the energy currency of the cell). While we are awake we are constantly using ATP and as a result produce excess adenosine. Normally adenosine binding to adenosine receptors ( yes we are that lazy with names in biochemistry sometimes) triggers us ‘feeling tired.

Caffeine looks similar enough to adenosine that it can bind the same receptor, but it’s different enough that it doesn’t activate the receptor. Since now the receptor can’t actually sense the adenosine present, we feel awake. This also describes some of the side effects. The ‘crash’ is the caffeine releasing from the receptor and the receptor being able to sense the adenosine again. Also the reason you drink more caffeine now than when you first started to get the same result has to do with the fact that our body is actually kinda smart. It ‘knows’ that it should be feeling tired at some point and its solution is to up-regulate(make more of) the adenosine receptors. Now it will take more caffeine to blocks those.