The low-down on the different fasting strategies

Drinking water during a fast

With fasting being one of the 'hot' things to do right now, and a lot of different information on the web, it is easy to get overwhelmed. That is why I created this quick guide to the different strategies, their benefits and draw-backs, and who most likely will benefit from which.

There are several different strategies referred to as 'fasting' and 'intermittent fasting': daily time-restricted eating, weekly 24 hour fasts, 5:2 diet, fat-fast, water-fast, fasting-mimicking.

Below, we will first shine light onto the different long-term approaches (2 days and more) which tend to be done once every quarter or half-yearly, and then dive into the more day-to-day/weekly options further down.

Please note, there is considerable overlap in the different strategies and naming, but below explanations try to shed light on some of the differences:

Water fasting, aka 'real fasting'

How is it done?

This is the 'real deal' of fasting. Nothing other than water and potentially some supplements are consumed during a certain period of time, which can range anywhere from 2 days to 21 days. A time period often used is 5-7 days, as research has shown the benefits of fasting to really speed up exponentially after a few days. Any span more than 24 hours should be done only supervision with a trained medical professional.

Who is it for?

  • Water fasting can be an important tool for people with some chronic conditions, such as cancers and some autoimmune conditions.
  • It is also a great adjunct for already healthy patients that want to upregulate and optimize their health long-term, prevent the onset of degenerative conditions, and provide 'internal' anti-ageing to the cells.

Who shouldn't do this

  • People with a history of eating disorders
  • Women that are pregnant or breast-feeding, and women trying to conceive.
  • Females in their reproductive years with hormone imbalances such as endometriosis, PMS and other may do better with a fat fast (see below).
  • People, especially females, with thyroid issues including cold sensitivity, inability to loose weight, hair loss, may do better with a different approach.
  • People with anxiety may need to adjust.
  • If weightloss is the main goal, this may not be the best option for you.
  • If you have diabetes, gout and are underweight, you may need to modify.

Fat fasting ('keto fasting')

How is it done?

Fat fasting is similar to the 'real fasting' as in it can range from two to several days. The difference is that, rather than only consuming water, you are allowed and encouraged to consume pure fats during this phase. The reason behind it, is that some of the main benefits attributed to fasting such as increased insulin sensitivity, reduced glucose levels and autophagy, our body's process of cleaning up old/sick/mutated cells when it doesn't have to digest, are still activated during a fat fast. Potentially to a slightly lesser extend, but research is yet to be conclusive about this. Pro's are that it allows for an easier transition into fasting and tapping into ketones for fuel, keeping up your energy and mental focus throughout the fast.

Who is it for?

  • High performing executives, students, mothers, or anyone that cannot 'afford' the time out and rest that is needed to do the water only fast. The fat will boost brain function and energy needed to perform at the highest level on a day to day basis.
  • Anyone that hasn't previously done any fasting, tends to have blood sugar crashes and cravings. The fat will help you tap into your fat storage and balance blood sugar, while keeping up your energy and satiety levels.
  • This option is also a great tool for women that are trying to conceive in the near future, but would like to reap the benefits of a fast. The fats will support female sex hormone production, and signal the brain that it is not starving. Triggering starvation mode such as potentially occurring in calorie restricted (fasting-mimicking) or full water fasting can downregulate hormone production, which would reduce fertility (in the short run).
  • People that do not want to loose extra weight may benefit from the extra fat in this approach.
  • People wanting to preserve muscle mass. Studies have shown that as long as the body has enough fat to use for fuel, it won't burn up muscle mass. Though the long-term goal is that your body can tap into its own fat storage, and hence not as much additional fat needed, this approach can be good for people that are new to lower carb/keto approaches for the time it takes the body to relearn to tap into its own stores.

Who shouldn't do this

  • Pregnant and breast-feeding women and people with a history of eating disorders.
  • People with certain genetic predispositions that may make high fat diets less than optimal for them. They may benefit more from a real water fast or the fasting mimicking diet approach (which has moderate levels of fats).

Fasting mimicking diet

How is it done?

The fasting mimicking diet, as described and studied by Walter Longo, PhD, and his team of scientists at the University of California and the Longevity Institute in Milan, consists of a 5 day calorie restricted diet (between 500 to 750 calories per day), divided into roughly 45% calories from fat, 45% calories from antioxidant and fiber rich vegetables, and up to 10% protein. They have done extensive research into its effectiveness in cancer patients, people with autoimmune, cardiovascular, neurodegenerative and many other conditions.

Who is it for?

  • As the above strategies, it is a great tool for people with cancer, autoimmune, cardiovascular, neurodegenerative and many other chronic conditions.
  • It preserves the gut lining which can sometimes gets degraded in a water only fast, so this strategy may be more suitable to people with an already compromised intestinal lining (aka 'leaky gut').
  • Similar to the fat fasting, this is an easier approach to anyone that hasn't previously done any fasting and tends to have blood sugar crashes and cravings. However, it most likely will still leave you feeling hungry and tired for the first few days due to the restricted calorie intake, until your body has shifted to its own fat stores for energy (ketogenic state).
  • This is a better approach than the fat fast for people with the above mentioned genetic predispositions to problems with high fat diets.
  • Overweight people wanting to kickstart a weightloss protocol, as this approach will force you to burn your own fat for fuel faster than the fat-fast, due to the restricted supply of external fat. Make sure to limit to 5 days, and then shift to a cyclical ketogenic diet that includes more protein and carb refill days for long-term metbolism (weightloss) support.

Who shouldn't do this

  • Pregnant and breast-feeding women and people with a history of eating disorders.
  • Athletes, executives or anyone else that has a high intensity day-to-day they can't temporarily escape from.
  • Already normal weighted women who's goal is to shift a few extra pounds, and/or have hormone imbalances especially thyroid issues, may do better with a different approach (less calorie restriction, more protein).
intermittent fasting for optimal health within a functional medicine approach

Day-to-day/ weekly strategies, ie making fasting a lifestyle

Above we discussed the strategies that can be used as a total body reset, ranging from once every few months to once or twice per year.

Now let's take a look at the fasting approaches that can be incorporated day-to-day or weekly.

Time restricted feeding/ 'Intermittent fasting'

How is it done?

There are a few different ways to do it, but it basically means restricting the time you eat per day, and fast for the remaining window. Usually I recommend starting with a 12 hour over-night fast, which should be easily done, example finish dinner at 8pm, then don't eat anything other than water/tea/coffee (no coffee/ caffeinated tea at night) until 8pm the next morning. The real benefit starts once you extend this not-eating window to 14-18 hours daily, and compress the 'feeding window' down to 6 to 10 hours per day. Examples can be fasting in the morning, then having lunch at 12pm and finishing dinner by 8pm. Alternatively, some prefer starting early with breakfast, and then finish off by midday or early afternoon. Best is to time it to your natural circadian rhythm (are you a night owl or an early riser?), your social schedule (family meals, etc), and ideally pick one time frame that works for you and then stick to it consistently.

This is often referred to in the media as 'intermittent fasting', however, as you will see below, there are other set-ups that equally consist of times of fasting and eating (ie intermittent).

Who is it for?

  • This is a great day-to-day strategy for anyone wanting to benefit from some of the great health boosts fasting has to offer, without it allowing for it to cut into the daily life/ productivity.

Who shouldn't do this

  • Pregnant and breast-feeding women
  • People with extreme blood sugar swings that need to be balanced first
  • Women trying to conceive
  • People with adrenal and thyroid issues, especially females in their reproductive years may do better with and want to choose the modified version of the intermittent fast, see below.

Modified Intermittent fasting

How is it done?

It works like the time-restricted feeding explained above, however with the addition of allowing some pure, high quality fats during the fasting period. This usually consists of a 'bulletproof' inspired coffee (high quality coffee with butter and MCT or coconut oil) or tea instead of breakfast, and then eating a normal, nutritious meal for lunch and dinner. Only pure fats are allowed during the 'modified fasting' period, as it has been shown that they won't take the body out of the cellular clean-up (autophagy), allow for ketones to circulate, and still reduce insulin levels. Anything including protein and carbs will take you out of this phase and stop the 'fast'.

Who is it for?

  • This is great for people transitioning to a more ketogenic, intermittent fasting based lifestyle, as it supplies exogenous fats to fuel the body and brain while it relearns to use fat as fuel. Once the body has learned to use its own fat stores as fuel, and you want to loose some extra weight, you may want to shift to the 'real' time-restricted approach outlined above.
  • Women trying to balance their hormones and/or conceive, as the extra fat will support their hormone production and also signal to the body that it isn't in starvation mode.
  • People with a high intensity lifestyle such as executives, endurance athletes, mothers, etc, that need that extra fat for brain and physical sharpness.
  • This is also generally a safer option for people with thyroid and adrenal issues.

Who shouldn't do this

  • Pregnant and breast-feeding women may want to stick to 3 meals per day to make sure they get all the nutrients in that the fetus/baby needs to develop.
  • People with a genetic predisposition towards problems with a high fat diet may benefit more from the 'real' intermittent fast.

Weekly 24 to 48 hours fasting

How is it done?

You basically stop eating for 24 to 48 hours every week of fortnight, and only consume water/ tea/ and potentially coffee.

Who is it for?

  • People that have very balanced blood sugar levels already and are 'fat adapted', meaning their body knows how to tap into their fat storage at ease, where this doesn't interfere with their productivity.
  • Some 'busy' people find this an easy strategy to implement during their work week, ie only eat a large dinner.

Who shouldn't do this

  • Pregnant and breast-feeding women may want to stick to 3 meals per day to make sure they get all the nutrients in that the fetus/baby needs to develop.
  • People with adrenal issues.
  • People with blood sugar swings.
  • Females trying to conceive.
  • Females with hormone issues, especially those involving the thyroid, estrogen dominance and adrenals.

5:2 or 4:3 Diet

How is it done?

On 2 to 3 days per week only up to 500 calories are consumed per day. You can then eat whatever you like for the rest of the week.

Who is it for?

  • This can be a good strategy to reap some of the benefits of fasting and especially loose some weight, IF the person then doesn't binge the remaining 4 to 5 days. Often people find it easier to stay consistent with the daily intermittent fasting/ modified intermittent fasting for women.

Who shouldn't do this

  • Pregnant and breast-feeding women.
  • People with a history of eating disorders or that tend to binge.
  • It shouldn't encourage people to eat 'crap' food for the rest of the time.
Functional Medicine healthy plate for optimal nutrition and health

Bottom line is that there are many ways to reaping the benefits of fasting, however it is important to choose the one that is right for YOU, your life circumstances, current weight, hormone levels, goals and needs.

I always want to place emphasis on the importance of choosing high quality, nutritious foods when you do eat. You may be able to make up for some of 'bad eating' during a fast, however, to truely life to your full potential and allow your body to thrive, you want to make sure to include all the building blocks (nutrients) the body needs on a day to day basis, and ideally restrict any 'crap' to the occasional cheat (think 80/20 rule).

Was this helpful to you? I would love to find out in the comment section below.

If you need help navigating all of the conflicting information out on Doctor Google, would like support customizing any of the above mentioned information, as always make sure to contact a certified health practitioner of your trust that is up to date with the newest research or get in touch with me. I'd love to help. X

2 Comments

  1. Andezal Review on June 6, 2019 at 10:36 am

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    • Mirthe Eckl on July 9, 2019 at 5:59 pm

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      Mirthe

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