on a more relevant point I haven't read the keto diet by Lyle, but I did get a copy of his rapid fat loss e-book. It is without doubt the best nutritional giude I've ever read.
It talks about a scientific approach to crash dieting, as in only eating what is essential to health and function and no more. Not advocating the crash diet (neither does Lyle) but the hard facts on what the body needs is fascinating ... check it out.