There are very few rules when it comes to fasting; what you do is really between you and the Lord. These are some of the fasts practiced in the Bible.
The Day of Atonement (Yom Kippur) is a Normal Fast, the only mandated fast in the Bible. That one day fast lasted from sundown one day to sundown the next. By tradition, this was a fast from food, drink, bathing, wearing sandals and intimate relations.
A Regular Fast means abstaining from all food. Most people drink water or juice, but caffeine is to be avoided. After fasting for 40 days, the Bible says that Jesus was hungry. It does not say that He was thirsty.
A Partial Fast generally refers to omitting a specific meal or a specific food from your diet. Daniel and his friends asked permission to refrain from the king’s rich food so as to follow the Jewish dietary laws (Daniel 1:12). And in Daniel 10:2-3, he fasted from choice food, meat and wine as he mourned for his people and sought the Lord.
The Daniel Fast is a popular, short-term (21 day), partial fast. It is basically a vegan diet without any sugars, refined carbs, caffeine, or alcohol. The only beverage allowed is water. The Daniel Fast is considered safe, and many Christians follow it.
A Full or Radical Fast is a complete fast: no food or drink. Biblical examples are Esther, and Paul. It should be used with extreme caution, since it can be harmful to your health and in most cases should not exceed three days.
There are examples in the Bible of Extreme Fasting, lasting more than 3 to 7 days, but they are exceptions. They were the result of direct guidance from God, or a supernatural ability given by God. Examples are Moses, Elijah, and Jesus.
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It must be said that fasting should be done thoughtfully, carefully and healthfully. I don’t believe that God intends any Spiritual Discipline to lead to danger or harm. But again, that is between you and God.
So, what does God want? What does He say is important in fasting? More on that tomorrow.