I hate this description of what it means to be LCHF/KETO; and it is so often repeated. But where did these carb-lover types get this idea from? How about this as an alternative...

When excessive amounts of carbs are consumed, our bodies are quick to respond to the emergency. It is well known that high blood glucose levels (diabetes & pre-diabetes) are damaging to the body, so our metabolism makes it the first priority to burn or store as fat any excess carbohydrates consumed. When carbs are consumed within acceptable limits the body will turn to its preferred fuel source: fat. In this process both the food that we eat and our fat stores are readily available for energy. In a fat adapted state our bodies burn both glucose and fat for stable energy all day long. The fat is released as molecules called ketones, hence the name "ketogenic" or "ketone-producing" diet. This 'fat adapted' state is known as nutritional ketosis.

IMO - my definition is just as plausible. My body didn't come with a service manual that tells me what the "proper fuel" for my body is. But through my own experiences, it sure seem like Keto is running my body on premium fuel.