It is far from being that simple.
The body cannot synthesize its own carbohydrate although it can isolate it from components of fat and protein.
The body does need a small amount of carbohydrate to maintain brain function. Other than that it can use fat for most energy needs. That said, fat is a poor fuel for high intensity activity.
Weight control has more to do with calorie (energy) control than it does adjusting macro-nutrient proportions.
wrong, wrong and right
The body does create glucose from proteins, the process is gluconeogenesis.
The brain does not need any carbohydrates to maintain brain function, the initial ketogenic diets and what is still their primary use in the medical field came from attempts to control epilepsy in children, where it is very successful, and the children run it for years.
But weight control is all about volume of calories in vs activity. Outside of a minimal level of protein (to get Essential Amino Acids) and a certain level of fats (to get Essential Fatty Acids) the rest of the macros are pretty meaningless other than for comfort.
For men, getting enough saturated fat is critical, and cholesterol itself isn't a problem (as it gets broken down before hitting bloodstream, so doesn't contribute to serum cholesterol). If you look around at men who have done really low fat diets, their serum cholesterol goes down (120 and lower) but at the same time their testosterone levels go down.... so a high HEALTHY saturated fat level is important. The trick with that is that organic butter or butter ghee and coconut oil are basically the only two healthy saturated fat sources, and the butter is a little iffy
