Fasting comes in many different ways from fasting certain days or time restricted eating in which you eat only during a certain amount of hours and do not eat in others.
Bert Herring was one of the first to talk about it
www.bertherring.com/ac/fast-5/
Here you can download a free book shop.bertherring.com/collections/free-digital-downloads/products/the-fast-5-diet-and-the-fast-5-lifestyle-ebook (just select the option "I can't pay")
I am not so sure about Jason Fung. Anyone who puts the Daily Mail as a scientific reference in the end notes falls down near the trash.
The scientific accuracy of his book as been rated at 3/10 which means either he is either voluntary misleading his readers or is not really good. (www.redpenreviews.org/reviews/the-obesity-code-unlocking-the-secrets-of-weight-loss/)
Combine the "very bad" science with the Daily Mail, it tells you all you need to know.
Any diet that encourages quitting processed foods, refined grains and added sugar will work. Insulin - which Jason Fung blames for everything - has little to do with it, and everybody would be very aware that protein will raise insulin faster and higher than carb (whey protein will spike higher than white bread) . Beef will stimulate insulin as much as brown rice. So do low carb if you want to but stay low on protein! Healthy low or healthy low fat work exactly the same in controlled studies, so pick the one you like more.
Do you own research, using university professors instead of people who benefit financially from what they claim or people without any medical degree.
I recommend listening to Luigi Fontana who is the professor MM talked to in his BBC horizon. HIs recent book is very cheap, the path to longevity, but you can get the content by listening to him.
What works for someone , will not work for someone else.
What you eat in the fasting period is important because it will affect your health and your gut bacteria, preventing the dreaded yo-yo