I have some questions about fasting. First, what is fasting according to the Bible? Second, what is the correct way to do it according to the Bible? Third, can I fast not only from food but also from my favorite activities? Fourth, what are the purposes of fasting other than to increase our faith and our dependance in God? Fifth, is it okay if my purpose for fasting is that my body becomes healthier or my mind become more disciplined? For example I have fasted in eating snacks & reading novels and comics. Am I supposed to be suffering from not having my fun time. Or is it bad that instead I become healthier and become more disciplined with my schedule, and I did not really have a hard time from my fasting? Is it wrong if the fasting is actually fairly easy for me? I think fasting is supposed to be a hard thing, not easy. Is that correct? Not easy thing.
Biblically, fasting is the abstaining from food, either for ceremonial or for devotional purposes. Perhaps the most important passage in the Old Testament on fasting is Isaiah 58 in which God, through Isaiah, tells us the proper attitude for us who fast. It should not be a mere ceremony, but should be a time to humble ourselves before God, and to behave toward our fellow humans as God would. The Hebrew word for fast is sumu. It means abstaining from food. The Greek word for fasting is nesteuete, with the same meaning. In what is perhaps the most well-known New Testament passage on fasting in Matthew 6:16-18, Jesus says, “when you fast,” implying that fasting is a normal activity for a follower of God (although some might debate that this is because he is talking to a specifically Jewish crowd). The “correct” way to fast is to abstain from food for a particular period of time, either as a group, or as an individual, in order to call on God for a particular purpose or as a means to draw near to God. This is the biblical definition. There is no example in the Bible of “fasting” from something other than food. There is no precise format, setting, reason, or amount of time for fasting, although the biblical example most common was group fasting for a one-day period. This does not limit our options.
What about other kinds of “fasting?” What about abstaining from other things like social media or sweet foods or sex between marriage partners, or the reading of novels, or other kinds of abstaining from non-sinful kinds of pleasure as a means to ask God for something or as a means to draw near to God? My answer is that, technically, this is not fasting, at least according to the biblical definition. It is not my place to tell others that they cannot call this fasting. However, I suggest that those who use a biblical word such as fasting in a non-biblical way ought to be aware of the distinction. This is not to say it is wrong or bad. Not in the least! But I believe we ought to be aware of the biblical meaning of words and aware when we are using the word is a different way. For me, I prefer not to use the word fasting for anything other than actual fasting, but I am a Bible teacher and am perhaps more prone to be careful about using biblical word in biblical ways. Far be it from me to tell people they should not do this.
I already listed some biblical reasons for fasting, and they seem to agree, more or less, with the reasons you list. It is not my desire to limit the purposes to only these two reasons–in order to call on God to answer a certain prayer request or in order to draw near to God. Perhaps someone might fast in order to help themselves come to repentance on a particular area of their lives. Bottom line, fasting is for the general purpose of giving glory to God or coming close to God.
Science has demonstrated that regular but fairly short-term fasting is good for health generally. I am not a medical professional, so I do not want to make any strong claims here, but there are positive health results associated with fasting under certain situations for certain (but not all) people. However, if we are to call it a biblical or Christian fast, it should not be principally for this purpose. We can “fast” for health purposes, but if so, let us not confuse this with a Christian fast, which is always for spiritual purposes. If a spiritually-purposed fast has positive health benefits, that should be beside the point. It should not be the purpose.
Should fasting be “hard?” Yes. That is assumed, by definition, whether the “fast” is a biblical abstaining from food or a non-biblical abstaining from some other sort of pleasurable activity. If it is easy, then what is the point of fasting, as it is a form of dedicating ourselves to God. It is to draw our attention away from the world and toward God–into spiritual realms. If it is easy, it will not be effective. Exactly when, and how long you choose to devote yourself to God in this way is something for you to decide.