Orthodox, Coptic, and other pre-Great Schism Christians fast twice a week (Wednesdays and Fridays), where fasting is defined as eating only vegetables and grains. In addition, there are various other periods of fasting throughout the year, such as the 40 days before Pascha (Easter) and Christmas.
The intent of the fast isn't for health reasons, although from my own anecdotal experience it does seem to have healthful effects, such as sharpening the mind. The rules aren't set in stone but are an ideal for the purpose of cultivating self-discipline and a humble awareness of our limitations. If a person fasts from food but "consumes" their neighbor (through anger, jealousy, etc.), then the whole point of the fast has been missed.
The intent of the fast isn't for health reasons, although from my own anecdotal experience it does seem to have healthful effects, such as sharpening the mind. The rules aren't set in stone but are an ideal for the purpose of cultivating self-discipline and a humble awareness of our limitations. If a person fasts from food but "consumes" their neighbor (through anger, jealousy, etc.), then the whole point of the fast has been missed.