The answer
Many interpret the holy fifty-five days of the Great Fast as the forty days fasted by our Lord Jesus Christ plus the Holy Week. Then they have a hard time trying to justify the extra first week of fasting. In the Greek Orthodox tradition it was attributed to the Emperor's request. Those not abiding by the Greek tradition tried to justify it calling it a Preparation week. However, the theory adopted from the Church of Jerusalem which interprets he forty days in terms of eight weeks by five days a week is the correct reason for the holy fifty-five days of fast our Coptic Church is observing today. This is because we do not abstain on Saturdays and Sundays. Therefore, to have completed forty abstaining days, we need to fast eight weeks (fifty-five days).I believe that covering the whole forty days of our Lord's Fast, should be a very strong reason for fasting those fifty-five days.
Answered by His Eminence Metropolitan Youssef (opens in a new tab)