Here is a copy of Peter Leithart’s blog post on fasting. He properly places the reason for fasting not on hating the body or material things, but rather on loving creation enough to fast so others can have more. It is a good and proper corrective to much of the gnostic philosophy pushed by Christians who promote fasting.
“For many throughout church history, fasting is bound up with hostility to matter and the body. We refrain from bodily pleasures of food and drink to train our souls in disembodied life.
That’s not biblical. The biblical fast, as Isaiah 58 puts it, is to share food with the hungry and clothing with the naked. The true fast gives good things away to those who don’t have them.
Biblical fasting, then, assumes the goodness of material things, and the propriety of pleasure. After all, if good and drink and clothing are evil, why would we want to share them? Isaiah’s fast assumes that creation is so good that we want everyone to have a piece of it.”