The current rules on fasting
The first important point to make is that, traddie or not, the only binding rules (ie it is a sin to break) are those in the current Code of Canon Law (as modified by our bishop's conference). And they are:
- the Eucharistic fast - from food and drink except water and medicine, 1 hour before receiving communion;
- abstinence (no meat) on Fridays (but there is an option to substitute another suitable penance for this) except on Solemnities - of which the Feast of the Assumption is one; and
- fasting and abstinence on Ash Wednesday and Good Friday.
Tradition on fasting
Historically of course, the Church has prescribed much stricter fasting rules. Scripture tells us of course that fasting - along with prayer and almsgiving - is a key practice for every Christian. Fasting helps develop our control over desires, thus strengthening us for the battle against temptation. And there is a huge literature attesting to its broader spiritual value. So what are the options?
Well over time the Church has changed its general fasting rules several times. In addition, many religious orders and other groups within the Church have developed their own traditions in relation to fasting. The Carthusians, for example, still have a 'black fast' (bread and water - the black refers to the colour of the bread) on Fridays. Similarly, Benedictines traditionally only have one meal, served mid-afternoon on most Wednesdays and Fridays (traditional fast days in the early Church) throughout the year. So really it is up to you what regime you choose to adopt.
Most traditionalists, however, tend to follow, with varying degrees of strictness, one of the versions (they changed a few times in the twentieth century) of the Church's general fasting rules that applied prior to 1969. A nice summary of the earliest version of those rules can be found here on the excellent fisheaters website (fisheaters lists a twelve hour fast before the start of Mass for example, but it was reduced to three hours and water allowed in the 1950s).
So today, for example (as I mentioned in the post in the vigil below) is traditionally a day of fasting and abstinence, and that would certainly be a praiseworthy practice to follow.
Personally I would advocate some flexibility on these things - a twelve hour fast with no water is perfectly manageable for most people (unless you have to drive a long way) if you attend an early enough mass such that you are sleeping for most of the fast! But if you are attending an evening mass, for example, and have to work during the day, then I would suggest a three hour fast is more doable....
The other point is that fasts need to be counter-balanced with feasts! Something of the Jansenist influence lingers I think, in making us tend to forget this.
The point of fasting on a vigil is in part the contrast with the celebration.
Just as our Lord explained why his disciples did not fast while he was with them, in many periods of our history, major feasts were the only time that the Eucharist was received by most people. The extra fast was felt to be a particularly fitting preparation for that, with the feast continuing to remind us of the gift of himself in the Eucharist.
Solemnities used to be holidays, on which servile work was prohibited. If we can arrange to take the day off, I think that is a praiseworthy thing to do!
The liturgy of the feast day was typically much more elaborate, and other liturgical celebrations, such as Solemn Vespers, or Vespers of Our Lady would be an important part of the day.
The main meal on a feast day was typically something above the ordinary, and the day was marked by pageants and music. And there were often distributions of food, clothing and money to the poor.
Now it is impossible for most of us to recreate that kind of atmosphere for a feast like the Assumption tomorrow, but we can surely try to do what we can...