Feeding Humans: Fats or Carbs?

This debate usually has the goal of determining which one is better, or which is the "best" source of energy for the human body. But that's actually not at all how fats and carbs should be perceived. They both have a very specific function within the human body's cycle of energy consumption, and you should know exactly what they do, and why.

Carbs are the body's first line of energy production in the form of Glucose. And the reason for this is because Glucose is required for a myriad of bodily functions, from standard brain operation, to red blood cell support, of course, muscle contraction, and many others. And as such, glucose is the only molecule of Anaerobic Respiration, which is a process where the production of energy (ATP) from glucose by Glycolysis is achieved very rapidly and without the need for oxygen. This is done in small amounts, but it is where we get our energy for intense physical activity such as sprinting or weightlifting. All other energy, including most glucose and all fats, undergo Aerobic Respiration, to produce ATP, which takes much more time.

This may seem like carbs are "better" right out the gate, but there is a tradeoff for this quick energy production. Glucose generally must interact directly with cells within the body to provide the relevant ATP yield, which is why our bodies have a relatively complex distribution network for glucose through GLUTs (Glucose Transporters.) These transporters are vital to the optimization of glycolysis, and if any of the transporters, such as insulin, are hindered for any reason, there can be major consequences, i.e. Type 2 Diabetes. Our bodies do not need an exorbitant amount of glucose to begin with, it just needs what it needs, and nothing more. In fact, as soon as the body has enough glucose, it turns excess glucose into glycogen, and then once there is enough glycogen (around 1500-3000) calories worth, it turns the rest into fat. Glycogen is stored in muscles and in the liver for rapid energy use, but the human body can only store so much glycogen either.

Now why on earth would glucose, the essential and rapid energy source, just be turned into fat once the body has had enough? That's because fat is the body's primary fuel. It may not be the first energy source the body will utilize in certain functions, but that is all part of the greater efficiency in the human body. In a lean human body, with around 15-20% body fat, the majority of those fat stores are literally for the potential conversion to energy. A lean human body can store between 50,000-100,000 calories worth of fatty acid energy supply. As opposed to the 1500-3000 glycogen stores for the occasional sprint or deadlift. You can think of the human body like a hybrid vehicle, with the small electric motor (Carbs,) and the larger main gas engine (Fats.) The electric motor is required for startup and the initial boost, but the gas engine takes over for the rest of the drive.

To make matters even more interesting, there is an energy molecule derived from fats called a Ketone, that is only produced when eating little to no carbs, and the human body enters into a state of Ketosis. This molecule is produced by the liver as an alternative energy source and is actually pound for pound the most efficient energy source available to the human body. It beats out glucose for the top spot in peak brain function, and can match muscle and organ function on nearly every metric. Now why would such an amazing energy molecule only be available when we consume little to no carbs? This is yet another step into the Carnivore Mode of mind.