Own thoughts, personal experience, initially published elsewhere, in a different format, different language.

Fasting is ritualistic food abstinence. Completely natural process for the human body. Cavemen did not have food available daily.

In one form or another, most major religions still practice it or at least used to practice it previously. I believe that the Catholic tradition of not eating meat on Fridays is somewhat related, a milder fasting form.

⚠️ Disclaimer ⚠️

NOT A DOCTOR. NOT MEDICAL ADVICE. NOT SUGGESTING OR ADVOCATING.

The Why

Some do it for weight loss, but that is not my priority. My reasons are different.

Altered State of Mind

Usually kicks in a couple of days into the fast. Thoughts are clearer, easier to concentrate, faster to get into the FLOW. A legal high for straight edge practitioners. Somewhat similar to the buzz of a third no sleep day, but without the dangers of sleep deprivation. I assume that this happens because in both situations body enters a hunter mode overdrive, which engages hyper focus.

Does not happen on each fast, still trying to get the hang of it. The greater the physical overload, the lesser the psychological effect.

The freedom feeling of not being tethered to a fridge is very liberating too. Mentally. Revelation that previously believed to be vital dependency is completely optional.

Cell Regeneration

When all fuel reserves are depleted, body starts burning its own cells for energy. The empty stomach condition. Not all cells though. More precisely - not just any cells at random. Human body has a process called autophagy, which picks cells for retirement and consumption. Autophagy targets damaged and old cells to burn them for energy. Body will produce fresh cells to replace them when I start feasting. Feasting is opposite of fasting.

Same reason why I donate blood, although not very regularly. Bloodletting the old, of medium quality and regenerating new, fresh and of high quality. Although this process is not a targeted approach.

Fasting burns some muscle too, but it all easily grows back when feasting. I want my new cells to be of high quality. This means clean food and regular cardio.

Noticed an extra smooth skin effect. Not just face, but everywhere. Very likely due to the high hydration levels and no sugar. It does not go away immediately when feasting, sandpaper skin only happens after a sugar overdose.

The How

Compiled a protocol to follow based on previous experiences. First attempts were strictly water fasting, but water with minerals works better for me.

Most rules aim to avoid double mental and/or physical overloads. Fasting in itself is an overload, adding another overload might push the body over the limit. Difficult to manage, could result in medical safety issues.

Before the Fast

Easy to digest food. I usually go for bone broth or vegetable soup. Ideally a full day of only such food. Break this rule and the first day of fasting will be spent digesting leftovers in the gut. It means that the benefits would be delayed.

Regular cardio. At least a few days of running or other heartwarming exercises. Body needs to be prepared for the physical overload.

Strong mental state. Fasting itself is a mental strain, if possible, sort those issues beforehand to avoid double mental overload.

Regular sleep schedule, to deal with fasted insomnia easier.

During the Fast

Avoid sleepless nights. Insomnia is common during the fast. Short sleep too. Make actual effort to sleep at least few hours. Regular sleep schedule before starting helps massively. Waking up after five hours of sleep is normal. Body knows now is not the time to sleep, now is the time to go hunting.

Daily physical exercise. Does not have to be much, if only to assess the physical condition. Daily weigh-ins to keep track of the situation. Amount of weight loss depends. A kilogram per day is my norm.

Did experience some muscle cramps during my first water fasts. Solved them by taking minerals. Himalayan salt and supplements containing calcium (Ca), potassium (K), magnesium (Mg) and zinc (Zn).

Salt is the most important part. A teaspoon daily, dissolved in water. Helps with the food cravings massively. Supplements might not be that essential. Usually take a pack daily or every other day.

Hydration is essential. Loads of water. Several liters daily. Non-sparkling, that amount of carbon might not be good. Green or camomile tea works too. Black coffee is a crutch, used to do it to help with the cravings, but it could upset the stomach.

After the Fast

Break-fast, food to break-the-fast, should be VERY, VERY easy to digest. First meal is a very light consistency bone broth, no onions, no garlic or anything else that could upset the stomach. Empty stomach reacts badly with onions and garlic. Solid and chewable food is possible after an hour or two. Avocado, eggs. Small portions. Eat, wait, eat again later. Aiming to avoid carbohydrates, sugar in particular. Sugar is dangerous, because fasting lowers insulin resistance, this means low amount of fruit too, only veggies and lean meat.

This might be the hardest part. Not the whole week of fasting, but those few hours between the first broth and the avocado. Food gates are already open, but I cannot feast yet.
Break this rule to enter a world of stomach pain. Fasting contracts stomach, stretching it out is really painful.

Gut microbiome rebuild requires fermented food, for example yoghurt, kefir (fermented milk), sauerkraut.

Longer sleep is to be expected, to catch up for the short fasted nights.

Fruits are important, to receive vitamins, but need to be consumed with caution. Lowered insulin resistance means that sugar is dangerous during the first days, means that fruits should be very limited. Not none, because vitamins are still needed, just limited.

Last week’s fast (at the time of writing this in the original form)

Last meal pre-fast was on May 8 (Saturday) at 01:00 - chicken bone broth.
Break-fast was on May 15 (Saturday) at 19:30, also with chicken bone broth.
Fasting for over a week. Some hours short of 8 days. Completely without food, only with the previously mentioned minerals.

The goal was lung recovery and fixing a painful hip. Hip used to hurt previously after running a few kilometers. Idea behind fixing them was heavy usage during the fast, so that the autophagy process would target cells in those areas. Goal in the lung area was building back the ability to do 10 km non-stop run.

Ran 6 times during the fast. Had a lot of extra physical work after the third days' run. This resulted in exhaustion and physical recovery on days four and five.

Did not expect to do the 10 km during the fast. Fasted state meant that legs are not the next day. They are sore after the workout, but sleeping it off works. Non fasted state requires more downtime. Fasted redline is way lower, distance wise, but redlining is still redlining, and it achieves the same results. The physical limit is lower, but it means that it is faster to reach it and to actually push it. It is not the physical exertion that counts to make progress, it is the act of pushing the limit. Body registers physical overload and acts accordingly to build up those areas later. Feasted workouts require way more physical effort to send the same message.

The ability to just run non-stop for whatever distance is very liberating mentally. Just knowing that it is possible, if need be, without worrying about traffic, without the need to rely on external tools.

I suppose the next goal in this area should be the ability to dash a significant distance. Dash, not jog.

Side effect - Keto Rash

An itchy rash appeared a couple of days into the fast. Not the first time.

Every single time it did go away a few days after the fast. Tried searching about it, came up with the so-called keto rash. Most describe it as not dangerous, only annoying, because it itches. Among the reasons for keto rash were listed dietary issues and something about the body pushing out toxins.

Dietary issues could mean low protein.

Toxins are also plausible. Could have something to do with aluminum buildup in the armpit. Antiperspirants work by clogging sweat pores with aluminum.

Weight loss and diets

Not eating alone does not directly transform into weight loss. Cardio exercise is mandatory. The basic rule of any weight loss diet should be the ability to do that diet for a long time. Avoiding sugar has the biggest effect. Body only needs 20-30 grams a day. Fasting is the only way to not reach that level. All fruits contain loads of sugar, some vegetables are sugary too, but due to the amount of vitamins, both have positive benefits. Aiming to eat fruits in the first part of the day. Body will not have time to burn off the sugar, if consumed late. Not burning it means weight gain and sugar is the fastest way.

Sugar detox takes time, taste receptors change over time and regular food becomes acceptable without sugar. I gauge my acceptance levels based on whether I prefer 70% or 90% black chocolate.

Why cardio is important

Calorie restriction puts body into starvation, energy saving mode, which does not burn energy. Exercise is needed to burn the calories.

Week Day	Running distance	Morning weight	Weight loss since yesterday
VI	2.5 km	96.2 kg	none
VII	3 km	95.7 kg	0.5 kg
I	<2 km	94.6 kg	1.1 kg
II	none	93.2 kg	1.4 kg
III	none	92.3 kg	0.9 kg
IV	<2 km	92.1 kg	0.2 kg
V	>4 km	92.0 kg	0.1 kg
VI	<4 km	90.4 kg	1.6 kg

Completely without food, but significant weight loss happened only after exercise days. 100-200 grams is not significant weight loss. 100% / (92 kg / 0.1 kg) ~= 0.1%. Domestic scales are rarely calibrated for such precision, might be random noise.

To prove this hypothesis I would need to perform the deep fasting cardio experiment again, twice:

1. At least couple days of cardio, followed by couple rest days, followed by cardio again.
   A repeat of this data set.
   Would prove that this is not accidental correlation.
2. Cardio every single day, no gaps.
   Expecting to see linear weight loss without any drops.
   Would prove that the drop is caused by rest days.

Bone broth

Can be made in easy to digest form, if no onions or garlic used. Has a lot of collagen.

Collagen is very important after the fast. Link between dietary collagen and collagen in body may not be clinically proven yet, but personally I found it to work just fine. Collagen is used in joints - my hip pain went away. Collagen is used in the skin, to provide the elasticity effect which is very important after weight loss to prevent skin sag.

HOWTO make bone broth

Collagen is found in the cartilages and bones. Meat has different type, lower amount. Skin provides too much fat, useless for broth. Beef joints is the perfect source.

Simmer for 8 to 48 hours. Pressurised slow cooker is very useful. I usually test the progress by checking if cooked bones can be crushed using fingers alone. Water in broth can be evaporated by slow boiling to produce a concentrate, which has a longer shelf life, useful for storage.

Can be frozen for long term storage, which is handy for breaking the fast. Multi hour food preparation when fasted is a mental challenge. Especially bad when the fast needs to be broken early.

⚠️Bone broth carries a heavy metal contamination risk⚠️

️This depends entirely on the bones used. Dietary heavy metals, from contaminated water for example, end up in animal bones, which would be extracted during the long simmer.

Food safety regulations may assume that bones are not simmered for days and the so-called acceptable contamination levels are adjusted accordingly.

Might be a good reason to research vegan collagen options.