HOW TO GET STARTED WITH FASTING

You may have heard about intermittent fasting, 5:2 fasting, alternate-day fasting, water fasting, bone broth fasting, or a fasting mimicking diet. These all represent different methods, or as we call them, doses of fasting. 

Like any other medication or treatment, fasting comes in a range of doses because, just like a medication, the dose of fasting that we take will determine the effects and the side effects. The effects and side effects will in turn determine if we should or are able to take the medication again. We can take a large pill or a small pill, we can take it 3 times a day or just once. But if the side effects are worse than the benefit of the medicine, we will probably stop taking it.

Fasting doses

A dose of fasting is determined by several factors: the length (how many hours or days), how strictly you fast, and how frequently you do it. Each person’s dose is different, and depends on factors such as your health goals and your prior fasting experience. When we recommend a dose of fasting, we also take into account your hormones, stress levels, your lifestyle and obligations: all of these impact your resilience and fragility and thus your success with fasting.

With practice, our metabolic flexibility during a fast often improves. It can be challenging to fast if your body is used to using glucose, instead of fat, as a fuel source. When glucose, and its storage form, glycogen, are depleted, your body burns stored fat for fuel. The transition from burning glucose to burning fat is called the metabolic switch. 

Fasting duration

Most people should start with shorter fasts and build up to longer fasts as they desire. The longer the fast, the more fat is used up. Longer fasts can trade off with fasting frequency for weight loss; you can do longer fasts less frequently or shorter fasts more frequently, depending on your preference.

What do we mean by a short or a long fast? A short fast is typically under a day, often overnight for a period of 12 to 18 hours: the kind of fasting commonly known as “intermittent” (although all fasts are intermittent and punctuated by times of eating, so we tend not to use this term). A long fast is 3 to 5 days. Surprised? Our bodies can switch on powerful processes for healing and fat burning in only a few days.

Those healing, life-prolonging processes include autophagy, stem cell production, stress resilience, and mitochondrial regeneration. These reparative processes kick in more vigorously when fasting for several days.

A fast of up to 3 to 5 days is associated with an increase in metabolic rate, or BMR (basal metabolic rate). Fasting for longer than a few days–or, for instance, long-term calorie restriction in what we think of as a typical diet–negates the effects of fasting for weight loss by lowering your BMR. 

Fasting methods

A clean fast is the strictest and most challenging form of fasting. It excludes everything caloric that can stimulate insulin. It works in the theory that the smallest amount of insulin secretion will “break the fast.” A clean fast includes only water, electrolytes, and necessary medications. One advantage of a clean fast is that the complete lack of calories will deplete glycogen more quickly, thus getting you into ketosis earlier in the fast. Since there are no calories going in, more stored fat will be burned for fuel. Many people drink black coffee on a clean fast, as caffeine may promote a ketogenic state. But be mindful of too much caffeine–adequate rest is crucial for a successful fast. Coffee is generally felt to contribute to a clean fast and may even promote ketosis. The effect of caffeine on sleep must always be considered. You should avoid coffee if it affects your sleep. If you consume significant caffeine, you will want to avoid the possibility of withdrawal symptoms if you stop abruptly when fasting. Some fasting practitioners believe that a fast must be clean to be effective for weight loss or maximize the benefits of autophagy, but there is no evidence to support this.

A dirty fast maintains ketosis while making it easier to get through without discomfort by consuming some calories, such as bone broth, which has no sugar but contains collagen proteins. The amino acids in bone broth protein are not the anabolic (muscle building) type that stimulates mTor (which signals our cells to grow), so the longevity-promoting effects of the fast are preserved. A dirty fast may also include small amounts of foods that are high in healthy fats, like avocado. A quarter of an avocado contains about 50 calories and may relieve discomfort during a fast while maintaining ketosis. The same goes for grass-fed butter or cream added to coffee. A few olives or fibrous vegetables like celery can help get you through a fast with minimal symptoms. If you feel hungry when fasting, water, coffee, tea, or salt and electrolytes can be helpful, but if a few olives, a pickle, or a fibrous vegetable like celery make the experience easier, then go for it. Fasting is beneficial when it’s a recurring event, part of your lifestyle.

A faux fast, or fasting mimicking diet, contains more food while maintaining a fasting mode in your body. Research by Dr. Valter Longo at UCLA led to the development of a diet that restricts calories, sugar, and proteins to a degree that avoids stimulating insulin, mTor, and AMPK so that the longevity and healing effects of the fast. The diet is sold as a program called Prolon. A fasting mimicking diet can also be done at home with recipes that fit the framework of Prolon, although this method has not been studied to ensure the same clinical outcomes. (A study of the fasting mimicking diet with Prolon showed fat mass reduction, muscle mass preservation, improved glucose, lipids, and inflammation, and increased stem cells.) The fasting mimicking diet is easier for many people to do and may be less stressful for those who are fragile due to heart disease, diabetes, or older age. Faux fasts have healing benefits, but because of the extra calories, you will not burn off quite as much of your own stored fat.

Fasting tips to get started

Start with short fasts; these can be clean or dirty.
Stop eating after dinner; make a habit of limiting your meals to a window of 12 hours, increasing to 16 hours, one hour per week.
Perform some all-day fasts sporadically or try a 5:2 (five days of regular eating, and two days of 500-600 calories from ketogenic sources) or alternate day fasting pattern.
As your body acclimates, you may be able to increase your dose to 3-5 day fasts to maximize healing potential.

Don’t fast in a pattern that someone else determines for you. Your goals, your circumstances, and your health determine your fasting dose. To get encouragement, build confidence in your ability to fast, and expert answers, check out our monthly community fasts.