Research more about IF and learn outside of what I share to see if there is a different style of IF that is a better fit for you and your needs. While there is widely available research on the benefits of IF, you should also learn more about the potential of negative effects of fasting on sleep, alertness, cognitive-motor performance, mood and for those with a previous history or susceptibility with eating disorders.
An informative description of the proclamation of a fast is in Jeremiah 36:9. There the people of Judah convened, apparently for the purpose of national repentance. This at least is what Jeremiah instructed Baruch to encourage them to do (vv. 7-8). Moreover, Jeremiah refers to the anticipated event as a "day of fasting" (v. 6), suggesting a common practice known to him and the people generally. In fact, Isaiah had spoken of such convocations a century earlier ( 58:3-6 ), gatherings on special days for special purposes. Regardless of Isaiah's feelings about the abuse of fasting, it is obvious that he recognized it as a legitimate form of worship and that he found no fault with it being carried out on specially called occasions.
Eating all your meals in an 8-hour window (say, eating between noon and 8PM, and fasting the other 16 hours a day) causes significant weight loss without counting calories. While this type of intermittent fasting causes weight loss no matter what people eat, research shows that people who do it in a healthy manner lose twice as much weight (7% vs. 3% of their body weight) as those who fast while still eating junk. So it’s still important to follow a high-performance diet like the Bulletproof Diet while you fast.
Fasting can take up a significant portion of the calendar year. The purpose of fasting is not to suffer, but according to Sacred Tradition to guard against gluttony and impure thoughts, deeds and words. Fasting must always be accompanied by increased prayer and almsgiving (donating to a local charity, or directly to the poor, depending on circumstances). To engage in fasting without them is considered useless or even spiritually harmful. To repent of one's sins and to reach out in love to others is part and parcel of true fasting.
Of the two most popular methods, Sasson leans toward the 5:2 schedule as slightly more manageable, since you’re only reducing your intake twice a week. But again, that’s contingent on you being a responsible dieter on your days of lowered caloric intake, which requires an immense amount of discipline—especially when it comes to remembering to drink water. “You can go a long time without food, but only a few days without adequate hydration,” she warns.
In practice, however, I would be concerned with eating enough. Based on my experience, teaching yourself to consistently eat more is one of the harder parts of intermittent fasting. You might be able to feast for a meal, but learning to do so every day of the week takes a little bit of planning, a lot of cooking, and consistent eating. The end result is that most people who try intermittent fasting end up losing some weight because the size of their meals remains similar even though a few meals are being cut out each week.
The digestive tract is the part of the body most exposed to environmental threats, including bacteria, viruses, parasites, and toxins. It requires the most immune system support. When food is broken down in the intestines, it travels through the blood to the liver, the largest organ of the body's natural detoxification system. The liver breaks down and removes the toxic by-products produced by digestion, including natural ones and the chemicals now present in the food supply. During fasting, the liver and immune system are essentially freed to detoxify and heal other parts of the body.
In terms of your comment regarding water yes millions of people may do this and as you say it has little impact and harm. I however prefer to drink water on a regular basis; it is what the body is primarily made up of and what the cells need for repair and regeneration. That and because many of us often think we are hungry when in fact we are dehydrated and the body is wanting more water – wanting more fluids this is why I encourage people to drink more water during fasting days than do a total fast.
Fasting or intermittent calorie restriction may affect cancer and tumor development, but are not currently used as a form of treating cancer. In 2011, the American Cancer Society recommended that people undergoing chemotherapy increase their intake of protein and calories, but provided evidence that a short-term period of fasting may have benefits during chemotherapy. Chronic fasting is not recommended for people with cancer at risk for weight loss or a suppressed immune system.