I just finished reading two books that recently came out; "Fat for Fuel" by Dr. Mercola and "Primal Fat Burner" by Nora Gedgaudas.
Both are essentially the same book, down to quoting the same people and the same concepts. They differ in their practical advice and the research to support that. Gedgaudas is hardcore primal. She doesn't even advocate ghee butter. She practically lives like in an Ice Age and she doesn't even have xylitol, just occasionally some pure stevia as a sweetener. Gedgaudas is not a great advocate of fasting nor cold adaptation for those who are very stressed or ill-compromised, she basically encourages people to eat primal most if not all the time. It is basically an update to her first book "Primal Body, Primal Mind" but with recipes per each week and some interesting scientific updates.
Mercola is more mainstream, recommending proteins mostly from plant-derived foods such as seeds and nuts. He says that 12 grams of protein should be the limit for women, and a little bit more for men per each meal (assuming a person eats three times per day). He recommends dairy, coffee and other inflammatory foods. It looked like quite the killer diet for some food sensitive folk, but it is strictly keto.
Neither highlight the potential antigenic properties of eggs for quite a lot of people.
Both de-emphasize blood ketones as the final aim, but then do tend to get lost in the numbers and the how to, specially Mercola. He came across as living quite the life of the "rich and famous", unpractical for most folk, but practical for those with the time and self-drive. Mercola is a big fan of fastings and explains several of them. One is the "fat fasting" which includes coffee with fat. As expected, a manufacturer of coffee made one plan here:
_https://blog.bulletproof.com/rapid-fat-loss-protocol/
IMO, it doesn't look like a fasting. More like a lifestyle where you are in the run and only had time to drink coffee with some healthy fat. I don't think it should be called a fasting because technically speaking, it is not that.
My 2 cents!