Note the emphasis on ketosis as a temporary adaptive state. Our ancestors could not be in fasting-induced ketosis permanently because they would eventually exhaust their fat reserves (which were presumably far more limited than ours, owing to the simple fact that they ate less and moved more than we do). They would then progress from fasting to starving, and subsequently die.
I just have to tell you, just to remind you, I am a type 1 diabetic and have been for 34 years. My kidney function has been going down gradually for several years including 4 points from June of this year to August. My GFR score was 42 in August, which I was told was stage 3 kidney failure. As of October 24 — I just got the results today — but as of October 24 my GFR score was 57 — 60 is considered normal. 
This may require a lifestyle change for many families, so we advise families who are interested in the diet to learn more by reading some of our excellent printed resources and to talk to each person who regularly cares for the child to make sure there is agreement to try the diet. We usually encourage an appointment with one of our epileptologists to confirm that the diet is right for your child, and then an appointment with our ketogenic diet team to go over more of the details.
Furthermore, humans develop a condition dubbed ‘rabbit starvation’[7] when they eat a diet that is low in fat and carbohydrates, and high in protein (> 35% of total daily energy intake). This is due to the inability of the human liver to sufficiently upregulate urea synthesis to meet excessive loads of protein. Consequently, hyperaminoacidemia, hyperammonemia, hyperinsulinemia, nausea, diarrhea, and even death can ensue within 2 to 3 weeks. These effects were recognized historically through the excess consumption of lean wild meat by early American explorers.[8]
In many developing countries, the ketogenic diet is expensive because dairy fats and meat are more expensive than grain, fruit and vegetables. The modified Atkins diet has been proposed as a lower-cost alternative for those countries; the slightly more expensive food bill can be offset by a reduction in pharmaceutical costs if the diet is successful. The modified Atkins diet is less complex to explain and prepare and requires less support from a dietitian.[55]
The benefits above are the most common ones. But there are others that are potentially even more surprising and – at least for some people – life changing. Did you know that a keto diet can help treat high blood pressure, may result in less acne, may help control migraine, might help with certain mental health issues and could have a few other potential benefits?