Thanks to Suncloud for the recommendation

Marks' Basic Medical Biochemistry (Lieberman, Marks's Basic Medical Biochemistry) Paperback – March 29, 2012

[www.amazon.com]

I was able to get a used one (as new) for like $50. There are older versions for like $5. The older version may not have much changed.

There are books like "Vegan for Life" that tells you what to do. This book explains how nutrition works.

I had it for only a couple days. This is the book that explains all nutritional processes. If you want to master nutrition, get it. It comes with some negative parts like nutritional propaganda from American Associations, etc., and all that, which they try to pass with authority as proven science. I would not like doctors to tell me what to eat as they don't know much and would paraphrase what they read like a parrot but wearing a white coat. There are many different opinions on what to eat (nutrition is controversial after all), and their advice would be very questionable. It does have important information for people on high fat diets, fasting, carb diets, etc. It adds substance and complements other books.

You can read a good chunk of the book here (with the index, fasting section, etc) for free:

[books.google.com]