Fasting is both for the body and the mind. And below is a compilation from different sources on Why we should Fast, How to Fast, and so on, from the physical and the spiritual aspects.
Why Should We Fast
For General Health: Fasting promotes detoxification. As the body breaks down its fat reserves, it mobilizes and eliminates stored toxins. Fasting gives the digestive system a much-needed rest. After fasting, both digestion and elimination are invigorated and helps to actually shrinks the stomach- not in a harmful way, but restoring it to its normal size. People tend to be satisfied with less food after fasting. Fasting promotes the resolving of inflammatory processes, including painful inflammatory syndromes such as rheumatoid arthritis. Fasting quiets allergic reactions, including asthma and hay fever.
Fasting makes it easy to overcome bad habits and addictions. Many people have overcome tobacco and alcohol addictions by fasting, and even drug addictions. Fasting rapidly dissipates the craving for nicotine, alcohol, caffeine, and other drugs. Fasting is the perfect gateway to a healthful diet and lifestyle. Going on a fast gives you the motivation and enthusiasm to make a fresh start and commit yourself to a new and better way of life. (Several scientific resources available - do a search for yourself.)
For Healing: There are some who would be benefited more by abstinence from food for a day or two every week than by any amount of treatment or medical advice. To fast one day a week would be of incalculable benefit to them. CD 189 The sufferers in such cases can do for themselves that which others cannot do as well for them. They should commence to relieve nature of the load they have forced upon her. They should remove the cause. Fast a short time, and give the stomach a chance for rest. CD 190 In cases of severe fever, abstinence from food for a short time will lessen the fever, and make the use of water more effectual. But…not allow him to be restricted in diet for a great length of time until his system becomes enfeebled. While the fever is raging, food may irritate and excite the blood; but as soon as the strength of the fever is broken, nourishment should be given in a careful, judicious manner. If food is withheld too long, the stomach's craving for it will create fever, which will be relieved by a proper allowance of food of a right quality…If there is a great desire expressed for food, even during the fever, to gratify that desire with a moderate amount of simple food would be less injurious than for the patient to be denied. CD 190
For Faith: “If ye have faith as a grain of mustard seed, ye shall say unto this mountain, Remove hence to yonder place; and it shall remove; and nothing shall be impossible unto you. Howbeit this kind goeth not out but by prayer and fasting.” Mt 17:21 Instead of strengthening their faith by prayer and meditation on the words of Christ, they had been dwelling on their discouragements and personal grievances...In order to succeed in such a conflict they must come to the work in a different spirit. Their faith must be strengthened by fervent prayer and fasting, and humiliation of heart. They must be emptied of self, and be filled with the Spirit and power of God. Earnest, persevering supplication to God in faith--faith that leads to entire dependence upon God, and unreserved consecration to His work--can alone avail to bring men the Holy Spirit's aid in the battle against principalities & powers. DA 431
When Fasting is not Appropriate
When We do not choose right: The only hope for those who practice vile habits is to forever leave them if they place any value upon health here, and salvation hereafter. When these habits have been indulged in for quite a length of time, it requires a determined effort to resist temptation, and refuse the corrupt indulgence. The Mr. -, mentioned, had practiced these habits so long he seemed to have lost the control of himself… This man had gone so far he seemed to be left of God. He would go into the woods and spend days and nights in fasting and prayer that he might overcome this great sin, and then would return to his old habits. God did not hear his prayers. He asked God to do for him what had been in his power to do for himself. He had vowed to God, time and again, and had as often broken his vows, and given himself up to his own corrupt lust, until God had left him to work his own ruin. ApM 27
Those who have an impoverished diet: I have been informed that you have taken but one meal a day for a period of time; but I know it to be wrong in your case, for I have been shown that you needed a nutritious diet, and that you were in danger of being too abstemious. Your strength would not admit of your severe discipline ...I think that you have erred in fasting two days. God did not require it of you. I beg of you to be cautious and eat freely good, wholesome food twice a day. You will surely decrease in strength and your mind become unbalanced unless you change your course of abstemious diet. CD 191
Too Long or improper: It is true that there are unbalanced minds that impose upon themselves fasting which the Scriptures do not teach, and prayers and privation of rest and sleep which God has never required. Such are not prospered and sustained in their voluntary acts of righteousness…These are almost sure to become sickly. But Christ and true godliness are health to the body and strength to the soul. 1T 556 You are not called upon to fast forty days. The Lord bore that fast for you in the wilderness of temptation. CD 189
How to Fast
Eat sparingly of simple food: The true fasting which should be recommended to all, is abstinence from every stimulating kind of food, and the proper use of wholesome, simple food, which God has provided in abundance. Men need to think less about what they shall eat and drink of temporal food, and much more in regard to the food from heaven, that will give tone and vitality to the whole religious experience...Now and onward till the close of time the people of God should be more earnest, more wide-awake, not trusting in their own wisdom, but in the wisdom of their Leader. They should set aside days for fasting and prayer. Entire abstinence from food may not be required, but they should eat sparingly of the most simple food.
Abstinence from food: When Christ was the most fiercely beset by temptation, He ate nothing. He committed Himself to God, and through earnest prayer, and perfect submission to the will of His Father, came off conqueror. Those who profess the truth for these last days, above every other class of professed Christians, should imitate the great Exemplar in prayer. CD 186
Yield the Mind: The spirit of true fasting and prayer is the spirit which yields mind, heart, and will to God. CD 189
Need Sincere Repentance: “Is not this the fast that I have chosen? to loose the bands of wickedness, to undo the heavy burdens, and to let the oppressed go free, and that ye break every yoke? Is it not to deal thy bread to the hungry, and that thou bring the poor that are cast out to thy house? when thou seest the naked, that thou cover him; and that thou hide not thyself from thine own flesh?” Isaiah 58:6, 7 …seasons of fasting and prayer are indeed necessary; but they must be accompanied with sincere repentance and decided reformation. Without such contrition of soul, these seasons only increase the guilt of the wrong-doer. The Lord has specified the fast He has chosen, the one He will accept. It is that which bears fruit to His glory, in repentance, in devotion, in true piety. 4BC 1150
All references used with permission.
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