Therapeutic fasting (for me) is different from simple IF. I know, I know.
If a person has a disease, as was evident with the first patients Dr. Fung told us about, then I suggest that strict Fung Protocol is called for therapeutically.

When I fast for weight control, I accept the easier fasts Dr. Fung told us about, which included supplements and bone broth.

I think it all boils down to individual needs. Remember, I'm referring to the Fung Protocol from before his first book. I have no idea what he's recommending now.