A healthy person who is not perspiring much can go without food and water for about three days before the body begins to be stressed. And a healthy person can go without food for several days if he is drinking water. Thus, the amazingly long 40-day fasts by Moses, Elijah and Jesus Christ (Deuteronomy 9:9 Deuteronomy 9:9When I was gone up into the mount to receive the tables of stone, even the tables of the covenant which the LORD made with you, then I stayed in the mount forty days and forty nights, I neither did eat bread nor drink water:
Based on my experience, 24-hour fasts will get me into ketosis much faster than other methods like the fat fasting technique. To make the fast easier, I generally start my fast about 3–4 hrs before I go to bed the night before your full day fast. That means if I am going to fast all day Sunday, I start the fast on Saturday night right after my final meal. That way when I wake up, I am 11–12 hrs into my fast.
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.
Abstinence from food and/or drink as an element of private or public religious devotion. Fasting is nowhere commanded in the Torah and, in fact, is never attested earlier than the time of the judges of Israel (cf. Judges 20:26 ). The fact that Jesus and the disciples sanctioned it by their own example ( Matt 4:2 ; Acts 13:2-3 ), however, is sufficient justification for its practice in biblical times and, in fact, in modern times as well.
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 particular, consider fasting together with your family, small group, or church. Do you share together in some special need for God’s wisdom and guidance? Is there an unusual difficulty in the church, or society, for which you need God’s intervention? Do you want to keep the second coming of Christ in view? Plead with special earnestness for God’s help by linking arms with other believers to fast together.
God has reminded me the importance of preparation. I am not much for planning or preparing food in advance. However, since beginning the fast, the Lord has shown me that if I don't plan and prepare my food I will trip, fall or fail. There are so many temptation in an office setting. But, I was reminded that it is the same in the spirit. If I don't prepare by seeking him in prayer and worship daily, I will also trip, fall or fail.
Confront injustice through fasting. Fast as a way of expressing poverty in your body, to show solidarity with those who are impoverished by injustice in our fallen world. Divest yourself of some resources – food – for the good of others. Convert what you give up in food when you fast into gifts for the poor by estimating the cost of the food you would have eaten if you hadn’t fasted and giving that amount to charities that help poor people. Use the time you would have spent eating to serve people in need and help bring more justice to the world. Use your fasting to call attention to other people’s needs, such as when you’re working to find solutions to the problems causing injustice and want to inspire others (like government leaders) to take action as well. However, be sure not to call attention to yourself, simply to try to impress others with your fasting. Use fasting to confront injustices in our own attitudes and behaviors, as well – to break the hold of unhealthy habits in your life and help you grow in holiness. Ask God to give you a clear vision of what He would like your life to look like. Then, through fasting, express your complete surrender to that vision.
Carbs are only problematic when eaten excessively, beyond what your body requires. As long as you are eating low calories then carb intake will make very little difference in respect to fat loss. In other words, two diets of equal calories with varying levels of carb intake will result in the same level of fat loss. If you are still unsure then you can read this brilliant article by Lyle McDonald, Low Carbohydrate Diets Have No Metabolic Advantage. In addition, carbs in the main meal serve very important functions such as increasing leptin (improved satiety and metabolic rate), refilling depleted muscle glycogen stores and triggering the release of serotonin which will improve your quality of sleep and make you feel good.
Often, the major argument for periodic caloric restriction is that we did not evolve to eat three meals a day, every day. Some fasting proponents argue that our bodies were designed to be able to run on little or no food for as long as several weeks or even months. After all, we didn’t have access to a steady food supply until the advent of agriculture, and it wasn’t until the neolithic revolution that humans adopted a more regular meal pattern.
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?”
Understanding the potential adverse effects of intermittent fasting is limited by an inadequate number of rigorous clinical trials. One 2015 review of low-quality clinical studies found that short-term intermittent fasting may produce minor adverse effects, such as continuous feelings of weakness and hunger, headaches, fainting, or dehydration. Long-term fasting may cause eating disorders or malnutrition, with increased susceptibility to infectious diseases.
Methods of fasting also vary widely and cover a broad spectrum. If followed strictly, the person fasting does not partake any food or water from the previous day's sunset until 48 minutes after the following day's sunrise. Fasting can also mean limiting oneself to one meal during the day, abstaining from eating certain food types or eating only certain food types. In any case, the fasting person is not supposed to eat or even touch any animal products (i.e., meat, eggs) except dairy products. Amongst Hindus during fasting, starchy items such as Potatoes, Sago and Sweet potatoes are allowed. The other allowed food items include milk products, peanuts and fruits. It should be noted that peanuts and the starchy items mentioned above originate outside India.
Alternate-day fasting. Go back and forth between feasting days and fasting days. Eat like a king or queen one day, then eat nothing the next. This will probably be the most challenging fasting option for most people. If you try it, make sure you’re eating a ton on your feast days, otherwise you’ll fall into a major calorie deficit and you’ll likely feel miserable.
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. 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. 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. 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. 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.
Along with obligatory prayer, it is one of the greatest obligations of a Bahá'í. In the first half of the 20th century, Shoghi Effendi, explains: "It is essentially a period of meditation and prayer, of spiritual recuperation, during which the believer must strive to make the necessary readjustments in his inner life, and to refresh and reinvigorate the spiritual forces latent in his soul. Its significance and purpose are, therefore, fundamentally spiritual in character. Fasting is symbolic, and a reminder of abstinence from selfish and carnal desires."