Our bodies have a significant amount of metabolic flexibility. That means we can utilise any of the different macronutrients, fats, proteins or carbs, to produce energy. There are essential proteins and essential fats, but there is no such thing as an essential carbohydrate, so we could survive without any carbs whatsoever! You can see that all of the macronutrients filter down to the same molecule, Acetyl-CoA. It is this characteristic feature of macronutrient breakdown that means we can metabolise any of them to make ATP.
The above diagram gives a simplistic idea of how that works. Below is a chart that is a little more in depth.
We can see that three metabolic pathways exist for the breakdown of macronutrients that we eat. For Carbs this is Glycolysis, for Fats it is beta-oxidation and for Proteins it’s transamination. For now, that isn’t important.
We can see that Acetyl-CoA again at the bottom; it feeds into something called the Krebs cycle which allows us to produce ATP. As we know, ATP is the universal energy currency for our body’s cells.
The takeaway: Don’t be obsessed with Carbs, the body is very good at making energy from other food too.