I discovered this fasting today. :p I was searching generally about fasting habits among people. It is a bit funny that some Protestants come closer to our Tradition. Orthodoxy keeps Daniel's fast for almost 2000 years. I read in an article that Daniel's fast reminds Orthodox fast. I think that maybe our Fathers introduced this partial fast from prophet Daniel, as we do with the prayer for 3 times per day etc. In the greek text it says "ἐδίδου αὐτοῖς σπέρματα" in Daniel 1:16. Σπέρμα means seed in greek. So indeed Daniel ate everything that is made by seed (fruits, vegetables, legumes, grains). And indeed we, orthodox christians, during fasts we eat only these products without alcohol plus we avoid oil.