The ketogenic diet was developed for children suffering epileptic seizures it was never intended for optimum diet health but is a better alternative than having seizures each meal contained heavy whipping cream and basically replacing any carbs calories with fat and not lots of meat and protein
I find it strange that it's become so popular as a diet especially in America when most of the healthiest populations in the world follow a balanced diet but I guess it's easy for people to blame one macro nutrient than just be accountable for the over consumption and abundance of calorie
rich food available in the modern world