You might not have guessed it from the lines at your local Mega Burger drive-through, but fasting is chic. Americans, who are increasingly thinking about spiritual matters, are at the very least talking about fasting, and many are following through.

For example, just after President Bush's first inauguration, an evangelist named Bob Sjogren started a campaign to sign up enough Americans so that someone was always fasting and praying during the president's first term. The idea was so popular that Sjogren re-upped his efforts for Bush's second term. This development is part of the rise in fasting among evangelical Christians, not previously a fast-conscious group. The late Bill Bright, a prominent evangelical and founder of Campus Crusade for Christ, decided in the late 1990s to make promotion of spiritual fasting his life's final work. Well into his 80s, Bright went on several 40-day fasts. In 1998, he and Pat Robertson persuaded several million evangelicals to fast (or at least, say they were fasting) for 40 days in hopes of national religious renewal.

But most Americans know about fasting because of Ash Wednesday, the day many Christians begin their Lenten fasts. Adult Catholics, for instance, are asked to fast on Ash Wednesday and on Good Friday, with "fast" in this case being defined as eating a single meal on each of these days; additionally, Catholics are not to eat meat on Fridays during Lent. Informally, there is also the tradition of giving up something you like for the entire Lenten period. Many Christians choose a favorite food, such as chocolate or beer, as a sort of quasi-fasting.

Fasting isn't limited to Christians, of course. As the U.S. Muslim population increases, more and more Americans follow the Ramadan fast--one lunar month per year without food or drink during daylight hours. Jews continue to fast once a year--on Yom Kippur--to repent for their sins. Mormons fast the first Sunday of each month and then give the money saved on uneaten meals to the poor. Occasional fasting is advised by some interpretations of Buddhism and Hinduism, both growing in the United States. Traditional Methodists observe a weekly mini-fast, from Thursday evening until midday Friday. And, of course, some people fast for general spiritual purposes or in connection with political campaigns.