Return of 'True Hunger' and Shelton

So, it seems that Dr. Shelton says that fasting should be done until the return of true hunger, and ending it beforehand may yield only a fraction of the results, and an incomplete sort of outcome. Plus, he says that people may not gain the weight back.

This is odd, since that means a Water Fast should always be 21/25/30 days or whatever until true hunger returns, and a mere 14-day fast will have only fractional benefits.

So what to do?

Plus, can several medium-length fasts (8-14 days each) do what a single long fast (21+ days) can do?