This is first an answer to you question: I consider “long therm” when fast is longer than one week. (Person‘s starting BMI need to be known, as some may have stored energy for lot longer).
I do believe that fasting can do miracles for people with toxic overload.
But I do NOT believe overdoing fasting any more that eating!
I hope this helps you do get my meaning!
After all it is our body that does the greatest job, if we give a change!