"Fasting restores to those who practice it the father’s house from which Adam was cast out… God himself, the friend of man (Wsd 1,6), first entrusted to fasting the man he had created, as to a loving mother, as to a teacher. He had forbidden him to taste of one tree only (Gn 2,17) and if the man had observed this fast he would have dwelt with angels. But he rejected it and so found anguish and death, the sharpness of thorns and thistles and the sorrow of a miserable life (Gn 3,17f.) Now, if fasting is shown to be of value in Paradise, how much more must it be so here below to win us life eternal!".
(Link: http://thewinedarksea.com/index.php/weblog/on_fasting/ )
It is a fruitful meditation. I wrote about a similar theme some time ago, only I identified the forbidding of the Edenic fruit as a "dietary law" rather than a fast:
"Which takes me to the Garden of Eden. How many times have you read or heard a non-Christian, non-Jewish person complaining of the arbitrariness of that whole "tree of the knowledge of good and evil" nonsense? Why would God care if they ate this one fruit? There's no good reason for it -- whoever wrote it down even made a point of mentioning that the stuff was good to eat, so what's the big deal? Alternatively, you'll occasionally see a well-meaning believer defending the don't-eat-that rule on some practical ground of healthfulness or learning obedience or some such thing.
I think it's easier to understand the story -- and this works both if you take the story as something that really happened, or if you take it as a useful teaching story passed down by one of the world's most influential cultures -- as the story of the first dietary law. The first "We eat this, not that. Just because."Pointing at the fruit of the tree while uttering "In the day you eat of it you shall surely die" is not, inherently, any nuttier than pointing at your tablemate's cheeseburger while muttering, "That shit'll kill you." It doesn't matter that the modern health nut thinks that science is on his side -- it's still a prediction of religious significance -- because in reality the connection between any given cheeseburger and the untimely death of the cheeseburger-eater is practically zero, unless the eater chokes on it, I suppose. And even if a lifetime diet of cheeseburgers will shorten your life, who's to say that's not a reasonable choice for someone who likes cheeseburgers?But let's go back to dietary laws for a minute. It's significant that the breaking of a dietary law should play such a crucial role in the stories I'm speaking of. And it's not something that's alien to human nature either. There are many layers to the story, but I can't help but think that it's in part a lesson that there are limits to our natural inclinations. The tree's fruit was "good to eat," and there is no reason to assume the senses of the man and woman couldn't be trusted. Yet, as the story goes, it was better, in that place and in that time, to choose not to eat it. Resisting, if only on occasion, what we naturally want and can see is a good thing, must itself be something good. And doesn't that fit with our ordinary experience?"
(link: http://arlinghaus.typepad.com/blog/2010/04/dietary-laws.html )
One difference between a dietary law and a fast is that a dietary law is generally lifelong -- see the regulations of keeping kosher or halal, or the philosophy of an ethically committed vegetarian. Fasts, on the other hand, are generally temporary. In Jewish history, the permanence and complexity of the dietary law served many purposes -- among other things, to provide a concrete manifestation of identity among the chosen people, to clearly demarcate them from the peoples that surrounded them.
Another difference is that fasting can be regarded as a positive act, and when prescribed, as a positive duty similar to the duties of prayer and almsgiving. To adhere to a dietary law is more like a negative duty, a "thou shalt not." Negative duties are by their nature more binding than positive ones.
Does it matter whether we identify the forbidding of the fruit as a dietary law or as a fast? Or is it simply a third example of the same sort of class of commandments? Either way it is instructive to meditate upon the words, "for in what day soever thou shalt eat of it, thou shalt die the death."