A keto diet is well known for being a low carb diet, where the body produces ketones in the liver to be used as energy. It’s referred to as many different names – ketogenic diet, low carb diet, low carb high fat (LCHF), etc.
Since the glucose is being used as a primary energy, your fats are not needed and are therefore stored. Typically on a normal, higher carbohydrate diet, the body will use glucose as the main form of energy. By lowering the intake of carbs, the body is induced into a state known as ketosis.
Ketosis is a natural process the body initiates to help us survive when food intake is low. During this state, we produce ketones, which are produced from the breakdown of fats in the liver.
First off, you're in good company. More people—and more athletes—than ever are embracing a very low-carb, high-fat diet and sticking with it for months, or even years, on end. Once they successfully make the switch from using carbohydrates to using fat and ketones for fuel, they find they're leaner, healthier, and more mentally focused than ever.
But for every lifter who ends up loving this approach, you'll find another who had a miserable experience and bailed after just a few days. This is a shame, because they probably could have felt great if they had simply had a better plan—or a plan at all.