How It Works: Fast for 24 hours once or twice per week. During the 24 hour fast, which creator Brad Pilon prefers to call a “24 break from eating,” no food is consumed, but you can drink calorie-free beverages. After the fast is over, you then go back to eating normally. “Act like you didn’t fast,” Pilon says. “Some people need to finish the fast at a normal mealtime with a big meal, while others are OK ending the fast with an afternoon snack. Time it however works best for you, and adjust your timing as your schedule changes,” he says.
In more recent years, many churches affected by liturgical renewal movements have begun to encourage fasting as part of Lent and sometimes Advent, two penitential seasons of the liturgical year. Members of the Anabaptist movement generally fast in private. The practice is not regulated by ecclesiastic authority. Some other Protestants consider fasting, usually accompanied by prayer, to be an important part of their personal spiritual experience, apart from any liturgical tradition.
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.
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.