Historical Fasting During Advent

"Advent 2020 starts on Sunday, November 29, 2020...and ends on Thursday, December 24th 2020 ...." [1]

Quoted below, in part, without emphasis in bold, is from a blog post entitled What Ever Became of Advent Fasting and Penance?  written by Msgr. Charles Pope, in 2016 [2]:

...Advent, like Lent, is considered a penitential season. During these times we are to give special attention to our sins and our need for salvation. Traditionally, Advent was a time when would take part in penitential practices such as fasting and abstinence, just as is done during Lent.

In recent times, though, Advent has become almost devoid of any real penitential practices. Neither fasting nor abstinence is required; they are not really even mentioned. There is nothing in the Missal or other liturgical sources that refers to Advent as a penitential season....

During the Middle Ages, Advent observances were every bit as strict as those of Lent....

...

Today’s token fast (required only on Ash Wednesday and Good Friday) isn’t much of a burden: one full meal and two smaller meals. Is that really a fast at all? And we are only obligated to abstain from meat on the Fridays of Lent rather than the entire forty days.

Frankly, I doubt that we moderns could pull off the fast of the ancients, or even the elders of more recent centuries....

Perhaps this is a good illustration of how enslaved we are by our abundance. The more we have, the more we want; and the more we want, the more we think we can’t survive without. We are so easily owned by what we claim to own, enslaved by our abundance.

Some religious orders still adhere to some kind of fasting during Advent.  For example, those who belong to the Missionaries Of The Poor ("MOP") [3] abstain from meat and fish, expect for the Solemnity Of The Immaculate Conception Of The Blessed Virgin Mary on 8 December.  During this time their diet includes vegetables, eggs, beans and peas.  This information was given by a brother at the MOP monastery in Monroe, North Carolina, USA.

[1] https://www.calendarpedia.com/when-is/advent.html; emphasis in bold removed.

[2] https://blog.adw.org/2016/12/what-ever-became-of-advent-fasting/