This may sound like a strange statement, since we have been told that carbohydrates should be our source of energy. First it may make sense to look at what fat on our body really is but energy storage. It is very efficient at that for a single gram of fat packs 9 calories. Just to put this into perspective at my highest weight I had 76 extra pounds of fat on my body, this equates to over 260,000 calories of energy or enough to run over 100 marathons.
This conversion of fat to energy is called fat respiration as ketones versus glucose we get from carbohydrates. Our brain and heart prefer this source of energy provided this is what majority of our species has been eating as fuel for the majority of our existence. Here is a question, have you ever seen an obese lion? Most predatory animals will consume the fattiest flesh of the animals they catch (usually internal organs) and leave the lean portions to be consumed by the scavengers. Makes you think about the merits of that nice lean chicken breast or the more fatty hamburger patty or steak.
The process is detailed below showing how all foods can be used as fuel which I will not go into but if you want to learn more about the science of this check out this link.
Why not carbohydrates?
At one time only one teaspoon (about 5 grams) can dissolved in your bloodstream, if you body contains more than this you will have elevated blood sugar levels requiring your body to burn this excess. So that means that bagel you may have eaten for breakfast 5 of the 55 grams is actually usable in your body. The rest have to be stored away or quickly burned. So unless you are planning on going for a run right after breakfast best to skip that and go for some bacon and eggs, doesn’t that sounds better for breakfast anyway?