See also Prof Timothy Noakes, a professor of exercise and sports science, also a marathoner and ultra-marathoner. He struggled with his weight and pre-diabetic status until himself switching to a ketogenic diet.

http://www.runnersworld.co.za/nutrition/novel-dietary-ideas/

He doesn't say a ketogenic diet is right for everyone, rather that some people are very sensitive to carbs ("carbohydrate-resistant") and would be best served avoiding them.