A diagnostic fast refers to prolonged fasting from 8–72 hours (depending on age) conducted under observation to facilitate the investigation of a health complication, usually hypoglycemia. Many people may also fast as part of a medical procedure or a check-up, such as preceding a colonoscopy or surgery. Fasting may also be part of a religious ritual.


Intermittent fasting (intermittent energy restriction or intermittent calorie restriction) is an umbrella term for various eating protocols that cycle between a period of fasting and non-fasting over a defined period. Intermittent fasting is under preliminary research to assess if it can produce weight loss comparable to long-term calorie restriction.[1][2][3][4][5]
^ Jump up to: a b c Harris, L; Hamilton, S; Azevedo, LB; Olajide, J; De Brún, C; Waller, G; Whittaker, V; Sharp, T; Lean, M; Hankey, C; Ells, L (February 2018). "Intermittent fasting interventions for treatment of overweight and obesity in adults: a systematic review and meta-analysis". JBI Database of Systematic Reviews and Implementation Reports. 16 (2): 507–547. doi:10.11124/JBISRIR-2016-003248. PMID 29419624.
^ Buchanan, Colin (27 February 2006). Historical Dictionary of Anglicanism. Scarecrow Press. p. 182. ISBN 978-0-8108-6506-8. In the 1662 Book of Common Prayer, there is a list of "Days of Fasting, or Abstinence," consisting of the 40 days of Lent, the ember days, the three rogation days (the Monday to Wednesday following the Sunday after Ascension Day), and all Fridays in the year (except Christmas, if it falls on a Friday).
Several animal studies demonstrated that intermittent fasting based on daily circadian rhythms prevents weight gain. Mice given unlimited access to high-fat lab chow ate throughout the day and night which resulted in obesity and type 2 diabetes. Other mice fasted for 16 hours and actually consumed the same amount yet they didn’t gain weight or have negative health consequences. The findings suggest that it was the timing of eating, rather than the amount consumed which determined weight gain.

You also want to avoid the counting calories and calorie restriction fallacies. Most people fail to appreciate that there are many intricate biochemical dynamics that occur that are unaccounted for when you just count "calories in and calories out." While animals like rats can achieve a 40 percent increase in longevity through lifelong calorie restriction, such a great effect is not seen in humans, and there are good reasons for that. As pointed out by Fight Aging:14


When you consistently eat every few hours and never miss a meal, your body becomes very inefficient at burning fat as a fuel, and this is where the trouble starts. It's important to recognize that, with few exceptions, you cannot burn body fat if you have other fuel available, and if you're supplying your body with carbohydrates every few hours, your body has no need to dive into your fat stores. When you apply intermittent fasting you not only avoid this but also will typically decrease your food costs and increase your health.


While this verse applies to our eternal destiny, the principle applies to our daily sojourn; as we humble and deprive our bodies through fasting, our spiritual man is made stronger and our senses more acute. This principle served the apostles well during the early church days. Their decisions were made through fasting and prayer; God gave them instructions and directions. “While they were worshiping the Lord and fasting, the Holy Spirit said, ‘Set apart for me Barnabas and Saul for the work to which I have called them.’ So after they had fasted and prayed, they placed their hands on them and sent them off” (Acts 13:2-3).
Also, for many people, a full 16 hours of fasting just isn’t realistic, says Cynthia Sass, a New York City– and L.A.-based performance nutritionist. She recommends 12 hours of overnight fasting at most and believes the 16-hour gap is especially tough on those who exercise early in the morning or late at night. “If fasting makes you feel miserable and results in intense cravings and rebound overeating, it's not the right path for you,” she says.
In Yoga principle, it is recommended that one maintains a spiritual fast on a particular day each week (Monday or Thursday). A fast should also be maintained on the full moon day of each month. It is essential on the spiritual fasting day to not only to abstain from meals, but also to spend the whole day with a positive, spiritual attitude. On the fasting day, intake of solid food during the day is avoided and only a light veggie meal around 5 o'clock is taken. Water can be taken any time as needed. If health does not permit fasting for a whole day, for example with Diabetes, careful planning is done to reduce or skip one meal.[92]
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.)
Some of this newly created fat is stored in the liver, but most of it is exported to other fat deposits in the body. While this is a more complicated process, there is no limit to the amount of fat that can be created. So, two complementary food energy storage systems exist in our bodies. One is easily accessible but with limited storage space (glycogen), and the other is more difficult to access but has unlimited storage space (body fat).
People can live days with no food and water, and weeks or several months consuming only water. In lab animals, when calorie intake is cut by more than 50 percent, they eventually die of complications from starvation. In the final stages of starvation, the body, depleted of glucose and fatty acids, turns to muscle protein for energy. Humans die when their body mass index (BMI) is around 12.
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.
As you can see all of the sample intermittent fasting meals included in the fat loss diet have a convenient source of protein, fruit and some healthy fats. This food combination is what I have personally found to be the most effective for staying satisfied on low calorie meals. The fruit is highly nutritious, easily digestible and is effective at replenishing liver glycogen.

Nuts and seeds make great snacks that are high-fat and can be eaten around 2:30 p.m. Soaking these beforehand can help neutralize naturally occurring enzymes like phytates that can contribute to digestive problems. Eat dinner around 5:30 p.m., and just like the 8-to-6 window plan, a dinner with some sort of wild-caught fish or other clean protein source with vegetables is a great option.
When Varady and her colleagues conducted a study that combined alternate day fasting and exercise, they allowed the participants to pick whether they wanted to exercise on a feasting or fasting day, and found there was no strong preference one way or the other. But the researchers were surprised the dieters actually reported feeling more energetic on fasting days.

Weight-loss resistance can often be due to an underlying hormone imbalance. Leptin resistance occurs when your brain stops recognizing leptin's signals to use your body’s fat stores for energy. This causes your body to continually store fat instead of using it. Intermittent fasting has been shown to improve chronic inflammation that can dull the brain’s leptin receptor sites.
With this information in hand, you should know exactly how to schedule meals when starting an intermittent fasting plan. And while it might seem complicated at first, once you get into the habit of fasting, it will feel like second nature and fit pretty seamlessly into your days. Just remember to always start slow and gradually work up to more advanced plans.
I've been doing this fast with Jentezen Franklin for many years. I have seen miracles done, he healed me from addiction to alcohol! I know these fasts are hard, the spirit is willing, but the body is weak! I've fallen on past fasts, but asked God to forgive me, and went on. It's a physical struggle, but oh so worth it in the end! Please don't give up. 21 days is nothing compared to what's waiting for you at the end, and during the year! I've done the water only fasts, as well as the Daniel fast, which I'm doing now, that in itself is a struggle for me, as I don't care for fruits and vegetables much. God is his mercy and Grace see's each of our hearts, and knows we yearn for his closeness, but also he knows we are weak. Please keep praying and seeking, you won't be disappointed.
When I was forty-two years old, I went to an Assemblies of God camp in Alexandria,Minnesota, to speak for a women's retreat. The first two days of the retreat went very well, and then I had one day in between the first retreat and the second -- so many women had registered, the camp could not host all of the women at the same time. I took that day in this lovely place in Minnesota to enjoy the lakes and trees -- it was a gorgeous environment -- and to fast and pray about God's will for my life. I felt as if I was doing a lot of good things, but I also thought I might miss God's best for me. I longed to hear from God and to receive a revelation from Him about my life.
Catherine Gates is Senior Director of Content & Partnerships for Workmatters. She oversees the development, distribution and support of Workmatters content to equip marketplace leaders to live out their faith at work. She also builds partnerships with clients and other marketplace ministries. Catherine has a broad range of experience in technology, sales, training, public speaking and curriculum development. She’s passionate about her faith and helping people tap into more of God’s best for their lives while bringing God glory.
Another big concern of mine, but it turns out this fear was unfounded. We’ve been told by the supplement industry that we need to consume 30 g of protein every few hours, as that’s the most amount of protein our body can process at a time. Along with that, we’ve been told that if we don’t eat protein every few hours, our body’s muscle will start to break down to be burned as energy.
IF might sound wacky to some, but there’s evidence that intermittent fasting for weight loss does work. One 2016 study in the Journal of Translational Medicine found that people who practiced IF for eight weeks lost more body fat than those in the control group. Another 2012 study from the Nutrition Journal suggests that IF can help obese women lose weight as well as lower their heart disease risk.
Because it simplifies your day. Rather than having to prepare, pack, eat, and time your meals every 2-3 hours, you simply skip a meal or two and only worry about eating food in your eating window. It’s one less decision you have to make every day. It could allow you to enjoy bigger portioned meals (thus making your tastebuds and stomach satiated) and STILL eat fewer calories on average.

         Refraining from eating food. The Bible describes three main forms of fasting: 1) The Normal Fast, involving the total abstinence of food. Luke 4:2 reveals that Jesus "did eat nothing." Afterwards "He was hungered." Jesus abstained from food but not from water. 2) In Acts 9:9 we read of an Absolute Fast where for three days He "neither did eat nor drink." The abstinence from both food and water seems to have lasted no more than three days (Ezra 10:6; Esther 4:16). 3) The Partial Fast-in Daniel 10:3 the emphasis is upon the restriction of diet rather than complete abstinence. The context implies that there were physical benefits resulting from this partial fast. However, this verse indicates that there was a revelation given to Daniel as a result of this time of fasting.
"I also discourage the idea of fasting for those who struggle with eating disorders that are making intake of food a challenge and concern in their daily living. The point of the fast is to combine it with a more intense, focused time of prayer that brings a greater communion with God, a greater empowerment of the Spirit, and a greater earnestness in your soul.”

The very simple and direct conclusions I draw are these: First, if the Bible teaches us to do something, I want to do it. I want to obey the Lord in every way that He commands me to obey Him. And second, if fasting and praying are means to a breakthrough that God has for me, I want to undertake those disciplines so I might experience that breakthrough!

^ Buchanan, Colin (27 February 2006). Historical Dictionary of Anglicanism. Scarecrow Press. p. 182. ISBN 978-0-8108-6506-8. In the 1662 Book of Common Prayer, there is a list of "Days of Fasting, or Abstinence," consisting of the 40 days of Lent, the ember days, the three rogation days (the Monday to Wednesday following the Sunday after Ascension Day), and all Fridays in the year (except Christmas, if it falls on a Friday).
Now I'm certainly not linking the devil to a piece of pie, but I am saying this: the devil will always call your attention repeatedly to the thing that is harmful for you, but he will do it in a way that makes you feel deprived if you don't indulge in eating, drinking, or partaking of what is harmful. The implication of the devil is always: "This is so good. Has God really said you can't have any of this good thing?"
Yom Kippur is considered to be the most important day of the Jewish year-cycle and fasting as a means of repentance is expected of every Jewish man or woman above the age of bar mitzvah and bat mitzvah respectively. This is the only fast day mentioned in the Torah (Leviticus 23:26-32). It is so important to fast on this day, that only those who would be put in mortal danger by fasting are exempt, such as the ill or frail (endangering a life is against a core principle of Judaism). Those that do eat on this day are encouraged to eat as little as possible at a time and to avoid a full meal. For some, fasting on Yom Kippur is considered more important than the prayers of this holy day. If one fasts, even if one is at home in bed, one is considered as having participated in the full religious service.
The other factors to consider with this diet are more concerned with your current weight. Lower calorie intake for most people will equal less fat. This is because, unless you’re a full-time athlete, most people do not need the number of calories they consume each day. They don’t burn that energy away, and as a result, it turns into fat. The 5:2 diet promotes lower calories on a weekly basis and high nutrient foods during the fasting days.
You’ll spike your blood sugar when you eat. If you’re fasting on a high-carb diet and you’ve powered through the cravings and lack of energy from low blood sugar, there’s a good chance you’ll eat a ton of carbs when you feast. You want to eat big meals when you fast to make sure you’re getting enough calories, but all those excess carbs in one go will spike your blood sugar in the opposite direction, from low to high.[14] High blood sugar causes fatigue and lack of focus. That raging hunger will also cause you to binge unnecessarily, and whatever carbs you don’t use will get stored as fat.

Weight-loss resistance can often be due to an underlying hormone imbalance. Leptin resistance occurs when your brain stops recognizing leptin's signals to use your body’s fat stores for energy. This causes your body to continually store fat instead of using it. Intermittent fasting has been shown to improve chronic inflammation that can dull the brain’s leptin receptor sites.
There are many studies documenting the benefits of fasting which include lowering the risk of type 2 diabetes, reducing cholesterol levels, enhancing the body’s resistance to oxidative stress (which is connected to aging and many chronic diseases), reducing inflammation (a key driver in many common diseases) and… weight loss! The weight loss benefit is how I first got introduced to Intermittent Fasting (or IF for short).

There are many promises God makes in His Word in regard to the blessings we will receive through prayer and fasting. In my book The Power of Prayer and Fasting, I talk about seven specific promises. I want to mention three of them here that I trust will bless you as you read. I have seen each of these promises come true in my walk with God, and I’m confident they also can live in you, through you, and will be yours as you call on God to do His will in your life.
Snacking throughout the day can be a major source of calories you don’t need and is often the ultimate pitfall for dieters. Make sure you stick to your fast by only eating three designated meals a day and leaving the extra snacks out of the equation. Cutting the excess sugar, carbs, and calories not only helps you lose weight but also helps your body become healthier too.
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. [1] 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.
Finally, fasting was frequently associated with supplicatory prayer. David prayed and fasted over his sick child ( 2 Sam 12:16 ), weeping before the Lord in earnest intercession (vv. 21-22). Nehemiah, having heard of Jerusalem's desolation, wept, fasted, and prayed that God would give him favor with King Artaxerxes of Persia so that he might return to his homeland and repair its ruins ( Neh 1:4-11 ). Esther, under similar circumstances, urged Mordecai and the Jews to fast for her as she planned to appear before her husband the king ( Esther 4:16 ). Clearly, fasting and petition are here one and the same (cf. Jer 14:12 ).
It may sound really hard at first, but at least eight hours of the 16 is spent sleeping. There's also a lot of downtime between dinner and sleeping that adds up. Just be patient with yourself, and you'll find your body adjusting to this new eating schedule in no time. If you're looking to get started now, what better way than planning what you're going to eat during your eight-hour eating window?
For some, fasting may be easier to maintain if viewed as a semi-regular activity throughout the week. If you don’t think you can cut down on calories every day of the week at first, try a low-calorie fast for only two days a week. However, you have to be careful about this schedule: just because you’re not fasting every day doesn’t mean that your “off days” should be used to binge on high calorie foods. 
The physiology of fasting has been widely studied and documented by medical science. Beneficial effects such as lowered cholesterol and improved general functioning have been shown. Fasting as a treatment for illness and disease has been studied less, although some studies around the world have shown beneficial results. A 1984 study showed that workers in Taiwan who had severe chemical poisoning had dramatic improvement after a ten-day fast. In Russia and Japan, studies have demonstrated fasting to be an effective treatment for mental illness. Fasting has been featured on the cover of medical journals, although mainstream medicine has generally ignored fasting and detoxification treatments as valid medical procedures.
The five most common methods of intermittent fasting try to take advantage of each of these benefits. But different methods will yield better results for different people. “If you’re going to force yourself to follow a certain method, it’s not going to work,” says trainer and fitness expert Nia Shanks. “Choose a method that makes your life easier,” she says. Otherwise, it’s not sustainable and the benefits of your fasting may be short-lived.
“I used to crave foods like crazy when I first started,” says Dr. Sylvia Tara, author of The Secret Life of Fat, in a Bulletproof Podcast episode. “after six to eight weeks, I didn’t feel it anymore.” Dr. Tara kept a journal or foods and schedules to find how fasting worked for her. Her advice for weight loss with intermittent fasting? “For people who have those 20 pounds, know, number one, it can be done. Number two, it might be a bit more effort than you thought it was going to be… Third, know that it gets easier with time and you can maintain it. It really isn’t as bad once you get into it, and it’s extraordinarily effective.”
A systematic review of 40 studies found that intermittent fasting was effective for weight loss, with a typical loss of 7-11 pounds over 10 weeks. [2] There was much variability in the studies, ranging in size from 4 to 334 subjects, and followed from 2 to 104 weeks. It is important to note that different study designs and methods of intermittent fasting were used, and participant characteristics differed (lean vs. obese).  Half of the studies were controlled trials comparing the fasting group to a comparison group and/or a control group (either continuous calorie restriction or usual lifestyle), with the other half examining an intermittent fasting group alone. A brief summary of their findings:
The discipline of fasting entails that, apart from Saturdays, Sundays, and holy feasts, one should keep a total fast from all food and drink from midnight the night before to a certain time in the day usually three o'clock in the afternoon (the hour Jesus died on the Cross). Also, it is preferred that one reduce one's daily intake of food, typically by eating only one full meal a day.
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