At first I questioned, “Is this truly God's call for me?” Forty days was a long time to go without solid food. But with each passing day, His call grew stronger and more clear. Finally, I was convinced. God was calling me to fast, and He would not make such a call without a specific reason or purpose. With this conviction, I entered my fast with excitement and expectancy mounting in my heart, praying, “Lord, what do you want me to do?”
The combination of fasting and praying is not a fad or a novelty approach to spiritual discipline. Fasting and praying are not part of a human-engineered method or plan. They are not the means to manipulate a situation or to create a circumstance. Fasting and praying are Bible-based disciplines that are appropriate for all believers of all ages throughout all centuries in all parts of the world.
Intermittent fasting is a diet regimen that cycles between brief periods of fasting, with either no food or significant calorie reduction, and periods of unrestricted eating. It is promoted to change body composition through loss of fat mass and weight, and to improve markers of health that are associated with disease such as blood pressure and cholesterol levels. Its roots derive from traditional fasting, a universal ritual used for health or spiritual benefit as described in early texts by Socrates, Plato, and religious groups.  Fasting typically entails a steady abstinence of food and beverages, ranging from 12 hours to one month. It may require complete abstinence, or allow a reduced amount of food and beverages.
In section 109, of the same book, Yudhishthira asks Bheesma "what is the highest, most beneficial" and fruitful "of all kinds of fasts in the world". Bheeshma says "fasting on the 12th day of the lunar month" and worship Krishna, for the whole year. Krishna is worshipped in twelve forms as Kesava, Narayana, Madhava, Govinda, Vishnu, the slayer of Madhu, who covered the universe in three steps, the dwarf (who beguiled Mahabali), Sridhara, Hrishikesha, Padmanabha, Damodara, Pundhariksha. and Upendra. After fasting, one must feed a number of brahmans. Bheeshma says " the illustrious Vishnu, that ancient being, has himself said that there is no fast that possesses merit superior to what attach to fast of this kind." 
Cons: Even though there is flexibility in when you eat, Leangains has pretty specific guidelines for what to eat, especially in relation to when you’re working out. The strict nutrition plan and scheduling meals perfectly around workouts can make the program a bit tougher to adhere to. (You can learn more about the specifics — as well as when to time these meals — directly from Leangains here and here.)
The purpose in fasting for God is not about giving up food; it is about removing the obstacles that get in the way of fully focusing on Him. Human beings are conditioned to eat, usually 3 meals a day and snacks. We are so focused on what we are going to eat next, we leave very little room in our minds for thinking about God. Removing the food will free up your mind so you can meditate on God.
Lowers insulin levels: Intermittent fasting acts on insulin in two ways. First, it boosts your adiponectin levels, which helps restore insulin sensitivity to prevent weight gain and diabetes. Second, fasting decreases your fasting insulin levels. Lowered insulin is the cue your body needs to make the switch to burning stored fat instead of glucose.
Not only that, but growth hormone is increased during fasted states (both during sleep and after a period of fasting). Combine this increased growth hormone secretion:, the decrease in insulin production (and thus increase in insulin sensitivity ), and you’re essentially priming your body for muscle growth and fat loss with intermittent fasting.
Martin Luther, founder of the Lutheran Churches, held that fasting served to "kill and subdue the pride and lust of the flesh". As such, the Lutheran churches often emphasized voluntary fasting over collective fasting, though certain liturgical seasons and holy days were times for communal fasting and abstinence. Certain Lutheran communities advocate fasting during designated times such as Lent, especially on Ash Wednesday and Good Friday. A Handbook for the Discipline of Lent delineates the following Lutheran fasting guidelines:
Those who only pre-loaded once a day, or not at all, lost just over 1.75 pounds (0.8 kilos). In all, 27 percent of the treatment group who pre-loaded with water lost more than five percent of their body weight, compared to just five percent of the control group. This makes logical sense, as thirst is often misinterpreted as hunger. Drinking water before settling down to eat will also make you feel fuller, so overall this strategy could result in eating less.
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.