you said, "I did not say that a healthy person starves and a sick one fasts when they abstain from nourishment, this was Bernarr Macfadden.."
Then why do you bring up 100 year old quotes unless you share the same opinions? Generally, opinions this old are mere speculations, which tend to turn out sometimes right, mostly wrong.
Then you echo hygienists' old speculation that "the body will generally suspend the appetite to divert digestive energy into the cleansing and healing process".
The body does not suspend appetite in order to "divert digestive energy". Those hygienists 100 years ago did not know about autophagy or that it is the main feature of fasting (check it out on wiki). It turned out that when the levels of nutrients in the blood run high, autophagy is inhibited, which is a wise measure. Consider what would happen otherwise to those unclaimed nutrients in the blood, if cells decided that they can't deal with it now, cause they have some autophagy to do.
Metabolism goes on all the time, whether we eat or not, because the cells do their work and require energy for it. When the body decides that it's time to do some housekeeping, in the form of autophagy of course, appetite disappears, because the cells literally feed on the junk proteins and other accumulated stuff that had been sitting around in their cytoplasm. Many intracellular infections are also cleared this way.
I have read Joel Fuhrman's book and it did not elucidate any processes that go on during fasting. He merely repeated some basics about ketosis and the rest was old hygienists speculations, not all of which were right. The value of the
book is in inspiring case histories, but that's about it.