It's..a diet book. It even has recipes.
I gave it 2 stars because it did describe some interesting ongoing research. 

The TLDR; is that you should eat nutritional food but protein is "bad" and caffeine is good, but don't you dare eat carbs. 70% of this would likely be very triggering to anyone struggling with ED. Quite a bit of the book was spent going on to limit or "don't eat this bad food or you'll succumb to aging disease."

Some of the science described was a stretch to the connections they tried to make. In addition, I was disturbed by the sheer lack (or at least acknowledgement of) poverty and other determinants as major determinant of health and aging.