There is no prescribed time in the Daniel Fast. Rather, the Daniel Fast is about limiting the types of food intake to vegetables and water. The word vegetable in the Scripture actually means fruits and vegetables as these were all allowed under the Jewish dietary laws.
Daniel asked the Chief of the eunuchs to allow his three friends and him to eat just vegetables and water for 10 days and then check in to see their condition. But that didn’t end the dietary restrictions to this 10-day period. It appears that instead, this was a lifestyle for Daniel and the others. If the only meat available to them was that which had been offered as sacrifices to idols, they did not eat it.
There was another time in Daniel 10 where he was seeking wisdom from the Lord and he consecrated himself in a fast of vegetables and water for 21 days. This is perhaps why so many link the Daniel Fast with a 21-day fasting period. “In those days, I Daniel, was mourning for three weeks. I at no delicacies, no meat or wine entered my mouth, nor did I anoint myself at all, for the full three weeks.” Daniel 10:2, 3
There are a couple things we see from this portion of Scripture. One is that it seems that Daniel had resumed eating meat. The meat that he rejected in Chapter 1 was that which had been offered to idols and false gods. For him to consume that meat would defile his body, which he had consecrated (set apart) to the Lord.
Secondly, we see that in this fast, Daniel ate no delicacies. With what is known of diets during that time, this probably referred to breads (especially yeast breads), sweets, and other rich foods.
So when you plan a Daniel Fast, you need to also decide how long you want your fast to be. Most Christians who will enter the 2008 Fast in January chose a 21-day fast. That’s because this is more of a corporate fast with Christians throughout North America joining together in a common effort to fast and pray.
Not everyone is starting on the same day, however most start on the first few days of January. If you are joining in a corporate fast with your church or a group of believers, then your start date might be determined. Otherwise, this is a prayerful decision you can make.
The same it true with the length of your fast. Remember that this is a spiritual fast, with the Daniel Diet serving as the definition for the foods that you will eat. So planning your fast should be serious and with a purpose. Spiritual fasting is for spiritual results. So consider your goals.
The common lengths of time for fasting are 1-, 3-, 7-, 10-, 21-, and 40-day fasts. Obviously, there is no set rule for any number of days. If you are new to fasting, you might want to start with 3 or 7 days. If you are more experienced, a 21 day fast is probably the one to match a fast for entering the New Year. The 40-day fasts are generally undertaken only a few times (if ever) in ones lifetime.
Keep in mind that there are many kinds of fasts — and there are numerous types of spiritual fasting. They vary in length and in the types and amounts of food intake. This site focuses on the Daniel Fast as it grows in popularity among the Christian community.