In 2012, Carolyn Corbin, who lives in the Channel Islands, got some firsthand experience with fasting’s flexibility. At 5 feet, 2 inches tall and 159 pounds, Corbin was overweight, with a BMI of 29.1. After seeing Mosley’s BBC show, she took up the 5:2 regimen, eating 500 calories two days a week and eating normally the rest of the time. She soon switched to water-only fasts two days a week. Since taking up the practice, the 65-year-old has lost 35 pounds and kept it off. “Forget calorie counting, diet food and diet drinks,” Corbin says. “Fasting for weight loss works.”
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.
Of the two most popular methods, Sasson leans toward the 5:2 schedule as slightly more manageable, since you’re only reducing your intake twice a week. But again, that’s contingent on you being a responsible dieter on your days of lowered caloric intake, which requires an immense amount of discipline—especially when it comes to remembering to drink water. “You can go a long time without food, but only a few days without adequate hydration,” she warns.

The biggest concern most people have is that Intermittent Fasting will lead to lower energy, focus, and the “holy crap I am hungry” feeling during the fasting period and ruin them. People are concerned that they will spend all morning being miserable because they haven’t consumed any food, and thus will be miserable at work and ineffective at whatever task it is they are working on.


3 days in a 16:8 ration – my body loves it. I don’t feel famished and look forward to my 8 hrs of eating window. I keep calories in check with a healthy balanced diet. My exercise begins after my last hour of fasting, I eat a few fruits (mango and raspberries) and an avocado (topped with a homemade crushed walnut dressing) and I’m good to lift weights and run. My body feels light and healthy. Amazing solution to any fitness junky.
Fasting ramps up your stem cell production.[6] Stem cells are like biological playdough — your body turns them into any kind of cell it needs and uses them to replace old or damaged cells, keeping you younger on a cellular level. Stem cells are great for your skin, joints, old injuries, chronic pain, and more. You can try stem cell therapy…or you can just fast.
Human growth hormone, or HGH, is naturally produced by the body, but remains active in the bloodstream for just a few minutes. It’s been effectively used to treat obesity and help build muscle mass, important for burning fat. HGH also helps increase muscle strength, which can help improve your workouts, too. Combine these together and you have an effective fat-burning machine on your hands.
Keep in mind; the purpose of a fast is to draw closer to The Lord. You are setting aside a specific time to fill up with more of God. It’s not a competition; don’t overthink it. Jesus lived as one of us for over thirty years, and fasted often. He understands what you’re going through. Matthew tells about one of Jesus’ fasts in Matthew 4:2, “After fasting forty days and forty nights, he was hungry” (NIV). This happened just before Jesus was tempted in the desert and then started His full-time ministry. Don’t underestimate the power of taking a step closer to God.
This type of fasting is also known as cyclic fasting. Intermittent fasting is a catch-all phrase for eating (and not eating) intermittently. In fact, almost all of the fasting methods below are types of intermittent fasting! Typical intermittent fast times range from 14 to 18 hours. The longest period any one of these plans would require you to abstain from solid food would be about 32–36 hours.
The Bridegroom Fast – This fast was initiated by the leaders of the International House of Prayer, and is observed on the first Monday, Tuesday, and Wednesday of each month. Based on Matthew 9:15, its focus is intimacy with Christ, who is described in the Bible as the bridegroom of the Church. The fast is accompanied by services in Kansas City, which are freely accessible by webcast. It is observed largely in charismatic circles.
Fasting should not be considered a "dieting method" either. We shouldn't fast to lose weight, but rather to gain deeper fellowship with God. Yes, anyone can fast. Some may not be able to fast from food (diabetics, for example), but everyone can temporarily give up something in order to focus on God. Even unplugging the television for a period of time can be an effective fast.
Many people who want to try IF choose the 16:8 method because it allows you to eat whatever you want for an 8-hour window and then fast for 16 hours. During the fasting period, you can drink water, tea, coffee, and even diet soda. The trick is to figure out what 8-hour eating window works best for you. Are you fine with skipping breakfast? Or do you work out in the morning and prefer to forgo dinner? Experiment with the eating and fasting intervals that work best for you. However, like all restrictive diets, there are some drawbacks. For one, drinking caffeinated drinks while fasting can disrupt your circadian rhythm, and therefore, your metabolism.
Whether you are considering a 12-hour fast, a two-day fast, or a daily low calorie fast, you should talk to your doctor before beginning a new eating regimen. Certain medical conditions may get worse with sudden changes in diet and some medications are affected by changing the foods you eat. A doctor can help you weigh the possible benefits and consequences of a fast to see if it’s right for you.

Intermittent fasting also has a number of added benefits over strict calorie restriction. For starters, it's a lot easier to comply with, and compliance is everything. The calorie restriction route is also extremely dependent on high quality nutrition — you want to sacrifice calories without sacrificing any important micronutrients — and this can be another hurdle for many who are unfamiliar with nutrition and what actually constitutes a healthy diet.


Fasting proponents will also note that there’s a long tradition of religious fasting, though the focus there tends to be more spiritual than health-oriented. “Many religious groups incorporate periods of fasting into their rituals,” this article points out, “including Muslims who fast from dawn until dusk during the month of Ramadan, and Christians, Jews, Buddhists, and Hindus who traditionally fast on designated days of the week or calendar year.”
Fasting must also be done in an attitude of humility. It is not necessary for others to know we are fasting; it is directed towards God. “But when you fast, put oil on your head and wash your face, so that it will not be obvious to men that you are fasting, but only to your Father, who is unseen; and your Father, who sees what is done in secret, will reward you” (Matthew 6:17-18).
Give your body time to adapt to fasting and under eating during the day. This adaptation process may take a few days or a couple weeks. The best part about this diet is that while you might feel slight hunger sensations at times there will be no junk/food cravings. Many people including myself find it easier to deal with a little intermittent hunger then to deal with sneaky food cravings. As well everyday you get to look forward to eating a very big and satisfying meal at night. This takes the grind out of dieting.
Before you start your IF plan, it's important to talk with a professional to make sure it's right for you. Women should be especially cautious as there are some mixed opinions on whether or not certain fasting protocols are healthy for female hormone balance. In addition, if you have adrenal fatigue or gut health issues you'll want to proceed with caution. If you have a history of disordered eating, you'll probably want to avoid fasting altogether..
On the other five days of the week, there's no calorie cap, and no food is off-limits. This freedom isn't permission to binge and make up for your two fast days, but it does mean you shouldn't feel guilty about eating a slice of cake. U.S. News experts evaluate the Fast Diet poorly in all rankings, mostly due to its tough-to-follow nature and health risks in some populations.
Fasting is important, more important perhaps, than many of us have supposed . . . when exercised with a pure heart and a right motive, fasting may provide us with a key to unlock doors where other keys have failed; a window opening up new horizons in the unseen world; a spiritual weapon of God’s provision, mighty, to the pulling down of strongholds. [Arthur Wallis, God’s Chosen Fast].

And that's not all, says Courtney Peterson, Ph.D., an assistant professor in the department of nutrition sciences at the University of Alabama at Birmingham. "Studies suggest you keep more muscle and lose more fat than on other diets, even if you lose the same number of pounds." That's because after about 12 hours of fasting, you run out of stored energy from carbs and start burning stored fat.
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 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.
Whether you're a speedy eater who overeats before your brain gets the message that you're full or you just never seem to be satisfied, IF might help. “When you're not eating all the time, your hunger hormones don't need to be released that often,” says Jubilee. “The body gets in a better hormonal balance, which enables you to get a grasp on your appetite.”
Of course, fasting — regardless of the method — isn’t for everyone. If you have any medical conditions or special dietary requirements, it’s smart to consult a doctor before giving intermittent fasting a shot. Anyone who tries it should also plan to be highly self-aware while fasting. If it’s not agreeing with you, or if you need to eat a little something to hold you over, that’s just fine. It takes our bodies time to adjust, and some require more than others. Keep in mind that hormones can make it harder for women to follow a fasting plan than for men. “Be cautious at first, and start slowly [with a shorter fast],” Shanks recommends. If it doesn’t make you feel better, try something different, or accept the fact that maybe fasting isn’t for you.
Mattson points out that, from an evolutionary perspective, the brain power that fasting generates makes sense. Mammals typically go days without food, often hunting on an empty belly. Semi-starved animals with enhanced smarts and energy would be more likely to obtain food and live another day. “If you are that wolf or lion, now a week with no food, you better be able to focus your mind and concentrate on what you need to do to get food,” he says.
DU: The biggest benefit of fasting is disciplining us to focus on God long enough to be changed by Him. I have seen brothers and sisters who, after spending much time in God’s presence through prayer and fasting, have been significantly empowered to carry out God’s call on their lives. From a medical perspective, there are a significant number of credible studies showing that fasting substantially reduces the risk for type 2 diabetes, heart disease, and cancer. I reviewed scientific literature on the health benefits of fasting going back up to 70 years, and what I found is that fasting improves our health span if it is done consistently and intermittently as a lifestyle.
Surprisingly, since I've started intermittent fasting I've increased muscle mass (up 10 pounds from 205 to 215), decreased body fat (down 3% from 14% to 11%), increased explosiveness (set a personal best with a clean and jerk of 253 pounds a few months back), and decreased the amount of time I've spent training (down from 7.5 hours per week to 2.5 hours per week).

If you're worried you’ll be starving while fasting, you’ll be pleasantly surprised! Intermittent fasting decreases your hunger hormone ghrelin, which in turn can increase dopamine levels in the brain. (Just another example of the gut-brain axis at work.) Fasting can also help free people from emotional eating and kill cravings by transitioning your metabolism from unstable sugar-burning to steady fat-burning.
I recommend counting calories—not forever, but for about two weeks—so you get a feel for what a regular day of eating feels like. I have used and like Cron-o-meter, Lose It!, and Fitbit to track calories. Don’t get bogged down in the details. If a type of food you ate is not in the database, find something similar or make an educated guess. You just want to make sure you’re in the ballpark.

As long as you are in a calorie deficit then meal timing is irrelevant. In some cases large late night meals have been shown to preserve muscle mass better on a diet and result in a greater loss in body fat percentage. I highly recommend reading Martin Berkhan’s article on the subject – Is Late Night Eating Better for Fat loss and Health. Check out this post for more on the differences between the Kinobody approach and LeanGains (Martin Berkhan’s approach).


In a 2017 study in Science Translational Medicine, 71 participants who completed the fasting-mimicking diet showed health benefits including weight loss, lower blood pressure and a drop in levels of the hormone IGF-1, which primarily stimulates growth but also plays a role in regulating blood glucose levels. And depending on how healthy you are, you may not need to stick to the diet too long. For instance, Longo says a healthy athlete may need to do it only twice a year, while someone who’s overweight may need to continue with it until they see the improvements they want.

One potential disadvantage of this schedule is that because you typically cut out a meal or two out of your day, it becomes more difficult to get the same number of calories in during the week. Put simply, it's tough to teach yourself to eat bigger meals on a consistent basis. The result is that many people who try this style of intermittent fasting end up losing weight. That can be a good thing or a bad thing, depending on your goals.
As researchers study the different fasting mechanisms to try to determine the ideal protocol for a variety of outcomes in a variety of populations, however, the general public must proceed by trial and error. That leaves dietitians such as myself concerned that the hype around fasting could encourage people to follow harmful plans that severely restrict nutrients, cause stress or unsuccessfully treat serious conditions.
You’ll run out of energy. When you don’t have anything in your system for several hours, your blood sugar will eventually drop below baseline. If you’ve ever had a blood sugar crash, you know how this state feels. Sleepiness, trouble focusing, lightheadedness, intense cravings, and the occasional mood swing typically accompany low blood sugar. Your cells run low on fuel and they start demanding that you give them more carbs.[13]
When your empty stomach starts to growl and begins sending your brain every “feed me” signal it can, don’t be content to let your mind dwell on the fact that you haven’t eaten. If you make it through with an iron will that says no to your stomach, but doesn’t turn your mind’s eye elsewhere, it says more about your love for food than your love for God.
In Methodism, fasting is considered one of the Works of Piety.[52] The Discipline of the Wesleyan Methodist Church required Methodists to fast on "the first Friday after New-Year's-day; after Lady-day; after Midsummer-day; and after Michaelmas-day."[53] Historically, Methodist clergy are required to fast on Wednesdays, in remembrance of the betrayal of Christ, and on Fridays, in remembrance of His crucifixion and death.[54][55] "The General Rules of the Methodist Church," written by the founder of Methodism, John Wesley, wrote that "It is expected of all who desire to continue in these societies that they should continue to evidence their desire of salvation, by attending upon all the ordinances of God, such are: the public worship of God; the ministry of the Word, either read or expounded; the Supper of the Lord; family and private prayer; searching the Scriptures; and fasting or abstinence."[55] The Directions Given to Band Societies (25 December 1744) mandated fasting and abstinence from meat on all Fridays of the year,[53][56] a practice that was reemphasized by Phoebe Palmer and became standard in the Methodist churches of the holiness movement.[57][58] Wesley himself also fasted before receiving Holy Communion "for the purpose of focusing his attention on God," and asked other Methodist Christians to do the same.[55] In accordance with Scripture and the teachings of the Church Fathers, fasting in Methodism is done "from morning until evening"; John Wesley kept a more rigorous Friday Fast, fasting from sundown (on Thursday) until sundown (on Friday) in accordance with the liturgical definition of a day.[55][59] The historic Methodist homilies regarding the Sermon on the Mount also stressed the importance of the Lenten fast.[60] The United Methodist Church therefore states that:
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