Classical Pentecostalism does not have set days of abstinence and lent, but individuals in the movement may feel they are being directed by the Holy Spirit to undertake either short or extended fasts. Although Pentecostalism has not classified different types of fasting, certain writers within the movement have done so. Arthur Wallis writes about the "Normal Fast" in which pure water alone is consumed.[75] The "Black Fast" in which nothing, not even water, is consumed is also mentioned. Dr. Curtis Ward points out that undertaking a black fast beyond three days may lead to dehydration, may irreparably damage the kidneys, and result in possible death.[76] He further notes that nowhere in the New Testament is it recorded that anyone ever undertook a black fast beyond three days and that one should follow this biblical guideline. Dr. Herbert Shelton advises that one should drink water according to natural thirst.[77] In addition to the Normal Fast and the Black Fast, some undertake what is referred to as the Daniel Fast (or Partial Fast) in which only one type of food (e.g., fruit or fruit and non-starchy vegetables) is consumed.[75] In a Daniel Fast, meat is almost always avoided, in following the example of Daniel and his friends' refusal to eat the meat of Gentiles, which had been offered to idols and not slaughtered in a kosher manner. In some circles of Pentecostals, the term "fast" is simply used, and the decision to drink water is determined on an individual basis. In other circles profuse amounts of pure water is advised to be consumed during the fasting period to aid the cleansing of internal toxins. Most Pentecostal writers on fasting concur with Dr. Mark Mattson who says that sensible intermittent fasting with a sensible water intake can strengthen the organism and assist thwarting degenerative diseases.[78]
Time-restricted eating is pretty simple to implement. If you finish dinner at 7 p.m., for instance, you wouldn’t eat anything again until at least 7 a.m. If you wanted to take it further, you’d extend the no-eating time until about 11 a.m. or 12 p.m. Because you’re sleeping for a large chunk of the “no eating” time, this is a good way to introduce fasting into your lifestyle and experiment without any major changes.

Fasting is always practiced prior to surgery or other procedures that require general anesthesia because of the risk of pulmonary aspiration of gastric contents after induction of anesthesia (i.e., vomiting and inhaling the vomit, causing life-threatening aspiration pneumonia).[1][2][3] Additionally, certain medical tests, such as cholesterol testing (lipid panel) or certain blood glucose measurements require fasting for several hours so that a baseline can be established. In the case of a lipid panel, failure to fast for a full 12 hours (including vitamins) will guarantee an elevated triglyceride measurement.[4]