Years ago people of the Catholic faith were not allowed to eat meat on Fridays. What was the reason for that?
The Fishing lobby.
Friday was designated a fast day. (Unlike, say, Monday, which most people find to be a very slow day.) This was in commemoration of the fact that it was the day Christ died. One was supposed to mortify the flesh by giving up luxurious pleasures such as meat.
Yes, Friday is the day of fasting or giving up certain pleasures. Ironically, the large peasant population throughout history has not been able to afford much meat. It would have been more meaningful to give up grains.
The Catholic Urban Legend is that one of the popes recommeded fish on Fridays in order to assist the fishing industry, which was going through financial difficulties.
From the site for The National Shrine Of Saint Francis Of Assisi:
Abstaining from meat on Fridays is still a common occurrence among many Catholics. It’s not necessarily a “years ago” thing.
Well, I wouldn’t call it the “Catholic” urban legend as I generally (not exclusiely) hear it from non-Catholics.
However, it is clearly and patently false. Friday abstinence was documented as early as the writings of Clement of Alexandria and Tertullian (both writing at the turn of the second to third centuries) at a time when the church was under periodic persecution and no “pope” had the authority to do anything to shore up the profits of any fishing fleets.
As noted, it was intended to show respect on the day of the week that Jesus was crucified.
We really only abstained from meat on Friday during Lent. That’s how it used to be, anyway. I’m no longer a practicing Catholic, so I don’t know if things have changed or not.
So much misinformation about this rather simple subject. I’m reminded of the time when a protestant friend ask me (I was raised Catholic) why Catholics were required to eat fish on Fridays…
The fasting rules have been changing fast. No meat on Fridays is out the window. When I was a kid we used to have to fast (ie. no food at all) starting at midnight on Saturday in order to receive communion on Sunday. Then it was reduce to 3 hrs before mass. Is there any requirement at all anymore? I have no idea.
One hour. Hardly a requirement at all.
IANAC, just married to one. Thought I’d chime in: poor people are exempt from the no meat on Fridays rule, as well as those that are employed doing hard labor. At least that’s how it used to be, I see that they made it one hour, which is kinda meh, to me. The Messiah gives up his life and you just have to give up meat for an hour? Jeebus. But then I am not even a Catholic, let alone a Theologian.
But my husband even though he doesn’t practice still stands by the no meat on (Lenten) Fridays rule. Even worse, he loathes fish with every ounce of his being (don’t ask me why he won’t eat a soy substitute or something). Me, I love it. So, he gives something up, and I get something in return. Works fer me. 
In the Latin Rite, the fast before communion was originally anything by mouth (food or drink) beginning at midnight. That had already changed by 1957 (but I’m not sure which year) to no food or alcoholic beverages 3 hours before communion and no drink (except water) one hour before communion. In 1969, that was modified to no food or drink (other than water or medicine) one hour before receiving comunion.
On Friday abstinence: The discipline of the church remains that one should abstain from meat on every Friday of the year unless Christmas (and maybe a couple of other important feasts) falls on a Friday.
That rule was modified so that there is no longer a sin associated with failing to abstain on Fridays outside the period between Ash Wednesday and Easter.
To correct myself (after others have reminded me of it), most Fridays were merely days of abstinence, not fast days.
That technically meant you weren’t allowed to eat Spam, but could eat Lobster Thermidor.
(Of course, a Catholic who was serious about it would have abided by the spirit of the thing and not have had anything fancy.)
You were allowed to eat, ahem, Beaver on Fridays, as the Vatican deemed it to be a “fish” because it spent so much time in the water.
In Irish, the word for Friday is De hAoine, Fast Day. Wednesday is De Ceadaoin, First Fast Day. And Thursday is De Deardaoin, day between the two Fast Days.
Growing up Catholic in the midwest we were not supposed to eat meat on Fridays during Lent.
I think that’s why you still see around the midwest in front of Catholic churches “Friday Night Fish Fry” signs.
Nowadays, with fish a luxury item in many menus, we should be eating Kraft Mac 'n Cheese on Fridays in order to keep with the “humble” foods idea.
Also, the very young and the very old have also been exempted from the Lenten fast/abstinence rules. It’s getting so a lay Catholic can barely engage in self-mortification any more 
The rule tends to be to avoid the flesh of warm-blooded animals; modern rather than folk taxonomy is applied where the knowledge is easily accessible to the masses.
Around here, the traditional Friday staple was salted dried cod, in olden times a cheap source of preserved fish protein for the poor. Plus herring and sardines as distant runners-up. In a fascinating twist of events, by now genuine North Atlantic cod is as expensive as good beef, and most people here eat faux-cod that’s really pollock (and it’s not that cheap either); the new Lenten-table favorite is kingfish (sierra) shipped frozen all the way from the Indian Ocean (let’s see how long that lasts).
1957???
Those parochial school teachers who insisted it was a straight-to-hell offense (c. 1957-1960) to eat a hamburger on Friday were lying???
They weren’t having enough fun telling stories about girls and boys burning in hell for missing mass or disrespecting their teachers or parish priests? Especially those parish priests???
Why, those @%#&$! penguins!
(Shakes head)
And, of course, receiving communion after having eaten a piece of toast, that was even worse. Not sure what was prescribed to make hell worse than it was already. Hey, I was a kid.