Hoddy suggests trying a plan for two weeks and keeping a record of how you feel and what you eat. You can switch to another one if it's making you grumpy, or you can modify it; when Hoddy fasted, she split one meal into two smaller ones on fast days so she could have dinner with her husband. Or follow a plan partway, says Peterson. "Any form of fasting helps burn fat, and extending your overnight fast a little—say, eating dinner earlier—is an overall health benefit."
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.
In a physiological context, fasting may refer to the metabolic status of a person who has not eaten overnight, or to the metabolic state achieved after complete digestion and absorption of a meal. Several metabolic adjustments occur during fasting. Some diagnostic tests are used to determine a fasting state. For example, a person is assumed to be fasting once 8–12 hours have elapsed since the last meal. Metabolic changes of the fasting state begin after absorption of a meal (typically 3–5 hours after eating).