- Q. What is the reason for these above mentioned fasting days?
A. One general explaining is that the reason for the fasts is in case one sinned over the festivals of long Sukos or Pesach holidays, and others say that it should be for an atonement before the raining and harvest seasons.
The days of Monday and Thursday were chosen because they are considered days of extra mercy from Heaven.
It is also serves to atone for any forbidden work which one may have performed on Chol Ha'moed. (Eliyahu Rabba 492:3).
Some authorities suggest that the Beahab fast is actually therapeutic in nature, intended to strengthen our bodies in preparation for the changing seasons which occur following Pesach and Sukkot. Levush (492:3 as cited also in Nitei Gavriel
Rabbi A. Bartfeld as revised by, Horav Yaakov Hirschman, Horav Dovid Pam, Horav Aharon Miller, Horav Chanoch Ehrentreu and Horav Kalman Ochs Shlit’a