[Evgeny]

Basically, your body runs on glucose. Everything else is a stop gap for you to get more glucose.

But don't forget that the body can make quite a lot of the glucose using a process called gluconeogenesis. And substances like amino acids, glycerol or products of fatty acid oxidation are used as precursors.

So, in essence - yes, it runs on glucose, but glucose does not necessarily come from dietary carbohydrates.