Before I consider the answer to the last question, I should perhaps detail my own perspective when it comes to fasting when I grew up Lutheran.
I knew that modern day Lutheranism was not the Lutheranism that even Luther would be shocked to find. The liturgy, in most places, has been scrapped for emotionally pleasing, theologically thin worship and practice. As a history buff, I always was curious about the early church and especially its praxis. The more I read, the more I found that the religion I grew up with had so divorced itself from its history and tradition that its raison d'etre was to be anything that the Roman Catholics weren't. But this raison d'etre wasn't monolithic, far from it. There were essentially two groups who were antithetically opposed. On the one hand, for one group, there was a great rise in Biblical fundamentalism as opposed to the view by another gourp that Scripture should be looked at organically, casting off what was relevant to one culture vs. another. One group remained "high church" while the other remained "low church." These two groups are best represented, at least here in the states by the ELCA and the LCMS. Jaroslav Pelikan, the great editor of Luther's works who became an Orthodox Christian toward the end of his life, once observed that the ELCA was becoming Methodist and the LCMS was becoming Baptist. But, both groups, despite their differences were unified by one thing: they weren't Catholic. Fasting was a Catholic thing so there was no way a Lutheran should ever do the same. I must say that such a way of thinking is being challenged on both sides, but that's a discussion for a different time.
As to fasting, I wondered why Lutherans shouldn't abstain from meat like the Catholics did on Friday. After all, wasn't Christ crucified on Friday? He gave up His own life, is it that unreasonable that I should give up chicken or red meat? Apparently, it was. I also remember that it was encouraged that Catholics fast during the Triduum, the three Holy Days of Maunday Thursday, Good Friday and Holy Saturday. I remember that I asked my mother if I could do this and I was told no. In her defense, I think she was more concerned about my health than worrying about being stolen away by "Catholic thinking." But once I was out of the house, I found that I could not do it since I had no anchor. No pastor would counsel me on this and found no benefits about this. When I pointed to passages in the Confessions, I was met by the typical response that such things were fine back in the 16th century, but not for us modern and enlightened Americans (no, that's not exactly what they said, but you get the picture). But if one were to examine the Lutheran Confessions, one can find several passages where fasting is specifically mentioned and even lauded.
However, it should be observed that even in the Lutheran Confessions, fasting is not condemned but there is the usual caveat. In the Augsburg Confession, we read:
Therefore, we do not condemn fasting in itself, but the traditions which prescribe certain days and certain meats, with peril of conscience, as though such works were a necessary service.
The wording, like many typical passages of the Augsburg Confession, indicates that fasting is good, but advises the faithful that they don't hold to any rule because that amounts to legalism and the "earning" of salvation. Now, in fairness to the authors of the Augsburg Confession, I'm sure they readily observed, back in the 16th century, a great many of faithful people who were fasting to win points with God, whether the cause was borne from guilt or shame or whatever and that there needed to be a corrective. But holding to a rule is not being legalistic. Why extol the spiritual benefits of such a practice if it is only practiced "when one wants to?" Such is the great peril of the Lutheran position: it is grounded in individuality (a precursor to our own Western sense of individual liberty) to the point that one becomes the sole arbiter as to what is spiritually beneficial. And if there is no difference, spiritually speaking, between fasting and not fasting, why not just jettison the practice all together? It's an untenable position. You can't say that x and the -x amount to the same thing. Do prayer and no prayer amount to the same spiritual benefits? If our Lord and Saviour Jesus Christ said that the faith to move mountains comes from prayer and fasting, then surely prayer alone is not enough and fasting alone is not enough, but they should both be incorporated.
Apparently, much of the interest in the subject of fasting can be traced back to a Scott McKnight book entitled Fasting. I have not read it but it has made waves in Lutheran and other Protestant circles. You can find out more information about it here. From what I've read about the author, he is an Anabaptist which puts him in the school of the radical reformers of Zwingli. There are some other books to on fasting including Fasting: Opening the door to a deeper, more intimate, more powerful relationship with God by Jentezen Franklin. I've not read this book either so if anyone has specific insights beyond what the reviewers on Amazon.com can tell me, please post them here. Based on the editorial review on Amazon.com, it looks like it's a book that would appeal to the Joel Osteen crowd.
Now, to address my question as to why fasting is becoming a such a hot topic outside of Orthodox and even Roman Catholic circles. Could it be rooted in the fact that the mainstream Protestant denominations are dying? I'm very serious about this. Recent statistics, even those published by those same Protestant denominations, all indicate that the number of people who are registered faithful members are dwindling? The ELCA, once 10 million strong is now under 5 million in the course of 30 years. Many of the people leaving such churches are not just heading to another Protestant body, but are either leaving the Protestants all together for atheism/agnosticism/do-what-you-feel-like Christianity or for the traditional religions of Catholicism and Orthodoxy. Orthodoxy is the only Christian confession in the Americas that is growing. Even the Baptists are dwindling in numbers. Those people who have left Protestantism for the Orthodoxy or Catholicism do so because they grow tired of a generic form of Christianity which plays to people's feelings and does little to shepherd a fundamental ontological change. Protestantism now has become more a bastion of entertainment for Sundays then a lifestyle that prescribes repentance. And now, many people have finally caught on and they are leaving the Protestants in droves to seek out the churches which actually demand repentance and change and have spiritual disciplines to effect such repentance. Not only are these people craving disciplines like fasting, they crave the Liturgy, the Church Fathers, the traditional hymns and not the anthropocentric nature of worship in most of America's Protestant Churches.
Thus, and again I haven't read either one of the books mentioned above, could this movement be inspired, conscious or not, to keep people from swimming the Tiber or the Bosphorus? Could the authors be thinking, "We're not Orthodox, but you don't have to be Orthodox to fast so please don't leave us?" What's next? More books by Protestants on the importance and practice of confession or the Divine Liturgy or on the Church Fathers? Now, maybe I'm going out on a ledge here with such a "conspiracy theory" but it's not unreasonable to think that the leaving of many Protestants for Rome or Constantinople because of the spiritual depths they have is connected by the publishing and discussion of church practices particularly esteemed by those two bodies. Just a guess.