Ever since I started eating again two days ago, I haven't felt like writing about it. That's because the exquisite mental clarity that accompanied me for the last week-or-so of the fast is no more. Now I am fooded, and the contrast is stark.
However, despite my relatively sluggish and clouded mind (when compared to fasting), I will summarize some details while they remain fresh.
If your time or attention is short, the pithiest points follow the heading "Summary and Key Points", below.
Earlier Experiences with Fasting
I first learned about the health benefits of fasting and lowering insulin just over a year and a half ago. Those were compelling enough that I immediately started a version of "intermittent fasting", and continued for a few months. I originally thought a ketogenic diet (which is very low in carbohydrates) would be too great a lifestyle change to try right away, but just a few months later I was ready. I did that for about four months, to great success.
In the second month of my ketogenic diet (Jan 2017), I tried fasting for five days. A few months later I went for seven days. Five months after that I fasted for 8.5 days. And during the past two week I fasted for over 10 days, a personal record.
Over the months, I've applied varying degrees of strictness (nearly always consuming < 200 cal / day, sometimes much closer to zero calories), consumed assorted supplements, and my experience with and understanding of prolonged fasting has evolved and progressed.
In the past year, I've also done many shorter fasts ranging from about 24 to 84 hours, as well as daily "time-restricted eating" more days than not since about September 2017.
Overall, I've lost approximately 30 pounds in the past 1.5 years, all while increasing my strength somewhat, and I believe I've dramatically improved my short- and long-term health projections. During this most recent fast I reached the lowest weight of my adult life. (I also have absolutely no fear of "rebounding" or regaining the weight, in the so-called "yo-yo diet" that nearly all traditional dieters experience. That's because fasting doesn't lower your metabolic rate the way popular diets involving calorie restriction do.)
Having previously summarized my experiences with prolonged fasts, what then makes this fast worth rambling on about?
Well, I felt great.
I felt really good (almost) the whole time.
There are a just a couple (easily avoidable) caveats that I'll mention, but otherwise this fast was remarkable for both the mental calm, clarity, and focus, as well as the physical energy and well-being.
Physical State
I didn't plan to go to the gym at all, but I had enough pent-up energy that I went swimming twice, on days five and eight (and spent considerable time in the jacuzzi and sauna), and lifted weights on day nine. Not to mention going for walks around the neighborhood at least once daily. I even felt physically well enough to donate blood on day 10 (more details below), and up until doing so had scant physical concerns during the fast. My energy was not significantly lower than in times of eating, in contrast to prior experiences.
Mental State
You know those times when your worries seem to sort of recede to the background and you feel calm, energetic, and ready to tackle any challenge? That's what I was feeling almost continuously for a week. While on the one hand I kind of missed food and looked forward to the pleasure of eating again, I felt an equal or perhaps greater desire to continue feeling the way I did on the fast. But most good things must end...
Why do I believe I felt so great during this fast? Why didn't I feel a lower mental or physical energy level as I had at times on previous fasts? Why didn't I experience sleep disruption as many people do, and I had once before?
Well, ignoring for a moment that my body is much more "fat-adapted" (accustomed to using fat for energy, including both body fat and dietary fat) than the average person thanks to over a year of fasting and intermittent low-carb eating, I think what sets this fast apart mainly boils down to one thing:
Sodium (commonly known as salt).
This time, I made a concerted effort to increase my sodium intake every day. Last time, I drank enough bouillon to get about 1 gram of sodium per day. This time, using a combination of bouillon, broth, stock, dill pickles, and straight salt I consumed anywhere from about 3-10 grams of sodium per day.
I also supplemented magnesium and potassium for insurance (and to prevent potential muscle cramping or palpitations), but I don't think those made nearly the difference that salt did.
Why does salt matter so much?
Long story made short, when the body's insulin level is low (such as when not eating sugar / carbs, or eating nothing) more sodium is excreted in the urine. On top of that, when fasting you may consume little or no sodium. And if more sodium is going out, and less is coming in....well you do the math.
Furthermore, if sodium in the blood goes low, blood pressure also drops (because water follows sodium). And low blood pressure results in symptoms like feeling lightheaded, confused, or weak. A lot of people complain of those types of symptoms when fasting, especially people who've never tried it before.
So by increasing my salt/sodium intake, I was able to largely mitigate any symptoms related to low blood pressure. And by using the other electrolytes (magnesium, potassium), my kidneys had plenty of fodder to play with when balancing everything out.
Another consequence of keeping the blood pressure up naturally (thanks to the salt) is less need for assistance from hormones like cortisol, norepinephrine (aka noradrenaline), and epinephrine (aka adrenaline). All of these hormones are elevated to some degree while fasting anyway, partly because they keep your blood sugar from going too low (low is good, but there are limits). But these hormones will be produced even more if your blood pressure is dropping due to low sodium. And not suprisingly, higher levels of those "stress" or "activation" hormones tend to also interfere with sleep, so they are probably the main reason some people experience insomnia while fasting.
So putting it all together, by increasing my sodium intake dramatically I was able to deter symptoms of feeling lightheaded, sluggish, or weak, and even make it easier to sleep.
And as a result...I felt fantastic! With the caveats below.
Caveats
Exercise and Heat Exposure
As mentioned above, I didn't really experience decreased energy levels during this fast, and actually felt rather energetic, especially after the first hour of the day. As a result, I decided to go to the gym a few times. Twice I went swimming, and once I did weight training.
I also spent a lot of time in the jacuzzi, especially on day eight, when I ran into a friend and kind of lost track of time while we chatted.
I think between the overheating on the eighth night and resistance training on the ninth day, it was a little much all within 24 hours, and contributed to feeling a bit worse in general the last couple days of my fast. Not to mention...
Giving Blood
I had just become eligible to donate blood again around the time I started fasting and was receiving more-frequent-than-usual notifications from the blood center about it. Initially I determined it would be too risky to give blood during a prolonged fast, (as it could worsen various potential symptoms), and if I did it in the early stages it could derail my plans.
But a few days later, feeling as well as I was in general, I gradually warmed up to the idea. I made an appointment for the 10th and final day of my fast. At the center, on a whim I switched from a regular donation to a "double RBC", or double donation (which I've never done before, fasting or otherwise).
I tolerated the donation well enough, just feeling cold but never lightheaded. But from that point on I did feel fatigued, and my heart rate became more easily elevated with activity. Those are totally normal symptoms after such a donation, but with 10 days of fasting on top of that....
So, all-in-all, blood donations are not really recommended during a long fast, especially not double donations. Shocker, I know. I don't really regret doing it, but I would do a normal donation, rather than double, if I had it to do over again.
Jet Lag
I came off the night shift about a week before starting this fast, so my circadian rhythm was still adjusting. It wasn't the smoothest sleep transition, so I still felt kinda groggy for about the first two-three days of this fast. After that I was fine.
Summary and Key Points
Let me explain. No, there is too much. Let me sum up.
Fasting was normal for humans to do for thousands (if you don't believe humans developed through evolution) or even millions (if you do) of years. Only in the past 50-100 years have we had things like grocery stores and refrigerators that made food readily and constantly available. Our ancestors for many generations were accustomed to fasting out of necessity for varying lengths of time, and if their bodies knew how to do it, so do ours.
Fasting is normal. And not only is is normal, it appears to be the only way to access certain healing and regeneration mechanisms, such as autophagy, and regeneration of the immune system (which can heal or at least improve many autoimmune conditions) and other organ systems. It's also likely the best available weapon again obesity, diabetes, and even cancer, not to mention heart disease. Many people have eliminated signs and symptoms of diabetes through fasting, as described in this new book, and studies have shown that cancer cells become easier to kill when fasting, resulting in more effective treatment with chemotherapy or radiation (as well as fewer side-effects). That's to say nothing of fasting helping to prevent cancer in the first place.
I could go on. And on.
If you're interested in the evidence in favor of fasting's health benefits, there is plenty to go around, and it's a lot more compelling than any counterarguments I've heard (which are typically steeped in the flawed nutritional dogma of the past few decades while ignoring most of the actual evidence and millennia of human history).
However, though fasting was the norm till just a couple generations ago, many people have never gone more than a few hours without food in their lives and can scarcely imagine doing so. That is our culture, that's how we grew up, and it doesn't help that misguided dieticians (among others) continue to recommend "small frequent meals" even to the people who would benefit the most from eating less frequently (such as the obese or diabetic).
So, here we are with an incredibly powerful beneficial practice known to humans for millennia and practiced both intentionally and out of necessity for countless generations prior to ours. Now that same practice, fasting, has been largely abandoned due to a few decades of misguided dietary advice and a culture of constant food. And by no small coincidence, now everybody is getting fat and sick (though refined sugar wants to claim its credit for that too).
Fasting isn't easy at first if you've never done it before. Just like running a 5K would be hard if you've literally been sedentary your whole life and don't prepare in any way. It's basically the same. Start doing something different with your body out of the blue and you'll likely struggle.
So start slow and give your body time to adapt, as mine has over the past year-and-a-half. I wrote here (under "Conclusions") about how to ease into it: basically start with time-restricted eating and/or eliminating refined sugar and other refined carbs for a time. That's like the warmups and short training runs you might do leading up to your first-ever 5K. After that, try some water fasts of 24 hours at a time, and then later for 36 hours. After a while the sky's the limit.
And as I've learned gradually--dramatically of late--getting enough of the right electrolytes, especially sodium, can make a prolonged fast much more comfortable than it might be otherwise. Not only comfortable, even euphoric.
Let the fasting begin. Now you'll excuse me while I go eat lunch...
Photos: Breaking the Fast
Specific Results of my 258-hour (10.5 day) Fast
I've already talked about how I felt during this most recent fast, but here are some specific stats (and below are images with my detailed daily notes):
"Food" List
A few people at different times have asked what I consume while fasting. The list below many not be exhaustive, but gives a pretty good idea about what I've tried.
Of note, on my first prolonged fast I intentionally ate about 200 cal / day with a high protein content. Since then I've decided that's counterproductive, and I tried to keep my calories as low as reasonably possible during the next two extended fasts. On the most recent fast, however, my calories were a little higher than before, for two main reasons:
By mixing and matching items on this list, or similar things, you can get quite a high sodium intake with easily under 100 cal. However, despite my relatively sluggish and clouded mind (when compared to fasting), I will summarize some details while they remain fresh.
If your time or attention is short, the pithiest points follow the heading "Summary and Key Points", below.
Earlier Experiences with Fasting
 |
| Some of what I've been "eating" |
Over the months, I've applied varying degrees of strictness (nearly always consuming < 200 cal / day, sometimes much closer to zero calories), consumed assorted supplements, and my experience with and understanding of prolonged fasting has evolved and progressed.
In the past year, I've also done many shorter fasts ranging from about 24 to 84 hours, as well as daily "time-restricted eating" more days than not since about September 2017.
Overall, I've lost approximately 30 pounds in the past 1.5 years, all while increasing my strength somewhat, and I believe I've dramatically improved my short- and long-term health projections. During this most recent fast I reached the lowest weight of my adult life. (I also have absolutely no fear of "rebounding" or regaining the weight, in the so-called "yo-yo diet" that nearly all traditional dieters experience. That's because fasting doesn't lower your metabolic rate the way popular diets involving calorie restriction do.)
Having previously summarized my experiences with prolonged fasts, what then makes this fast worth rambling on about?
Well, I felt great.
I felt really good (almost) the whole time.
There are a just a couple (easily avoidable) caveats that I'll mention, but otherwise this fast was remarkable for both the mental calm, clarity, and focus, as well as the physical energy and well-being.
How I Felt This Time
Physical State
I didn't plan to go to the gym at all, but I had enough pent-up energy that I went swimming twice, on days five and eight (and spent considerable time in the jacuzzi and sauna), and lifted weights on day nine. Not to mention going for walks around the neighborhood at least once daily. I even felt physically well enough to donate blood on day 10 (more details below), and up until doing so had scant physical concerns during the fast. My energy was not significantly lower than in times of eating, in contrast to prior experiences.
Mental State
You know those times when your worries seem to sort of recede to the background and you feel calm, energetic, and ready to tackle any challenge? That's what I was feeling almost continuously for a week. While on the one hand I kind of missed food and looked forward to the pleasure of eating again, I felt an equal or perhaps greater desire to continue feeling the way I did on the fast. But most good things must end...
Why I Felt this Way
Why do I believe I felt so great during this fast? Why didn't I feel a lower mental or physical energy level as I had at times on previous fasts? Why didn't I experience sleep disruption as many people do, and I had once before?
Well, ignoring for a moment that my body is much more "fat-adapted" (accustomed to using fat for energy, including both body fat and dietary fat) than the average person thanks to over a year of fasting and intermittent low-carb eating, I think what sets this fast apart mainly boils down to one thing:
Sodium (commonly known as salt).
This time, I made a concerted effort to increase my sodium intake every day. Last time, I drank enough bouillon to get about 1 gram of sodium per day. This time, using a combination of bouillon, broth, stock, dill pickles, and straight salt I consumed anywhere from about 3-10 grams of sodium per day.
I also supplemented magnesium and potassium for insurance (and to prevent potential muscle cramping or palpitations), but I don't think those made nearly the difference that salt did.
Why does salt matter so much?
Long story made short, when the body's insulin level is low (such as when not eating sugar / carbs, or eating nothing) more sodium is excreted in the urine. On top of that, when fasting you may consume little or no sodium. And if more sodium is going out, and less is coming in....well you do the math.
Furthermore, if sodium in the blood goes low, blood pressure also drops (because water follows sodium). And low blood pressure results in symptoms like feeling lightheaded, confused, or weak. A lot of people complain of those types of symptoms when fasting, especially people who've never tried it before.
So by increasing my salt/sodium intake, I was able to largely mitigate any symptoms related to low blood pressure. And by using the other electrolytes (magnesium, potassium), my kidneys had plenty of fodder to play with when balancing everything out.
Another consequence of keeping the blood pressure up naturally (thanks to the salt) is less need for assistance from hormones like cortisol, norepinephrine (aka noradrenaline), and epinephrine (aka adrenaline). All of these hormones are elevated to some degree while fasting anyway, partly because they keep your blood sugar from going too low (low is good, but there are limits). But these hormones will be produced even more if your blood pressure is dropping due to low sodium. And not suprisingly, higher levels of those "stress" or "activation" hormones tend to also interfere with sleep, so they are probably the main reason some people experience insomnia while fasting.
So putting it all together, by increasing my sodium intake dramatically I was able to deter symptoms of feeling lightheaded, sluggish, or weak, and even make it easier to sleep.
And as a result...I felt fantastic! With the caveats below.
Caveats
Exercise and Heat Exposure
As mentioned above, I didn't really experience decreased energy levels during this fast, and actually felt rather energetic, especially after the first hour of the day. As a result, I decided to go to the gym a few times. Twice I went swimming, and once I did weight training.
I also spent a lot of time in the jacuzzi, especially on day eight, when I ran into a friend and kind of lost track of time while we chatted.
I think between the overheating on the eighth night and resistance training on the ninth day, it was a little much all within 24 hours, and contributed to feeling a bit worse in general the last couple days of my fast. Not to mention...
Giving Blood
I had just become eligible to donate blood again around the time I started fasting and was receiving more-frequent-than-usual notifications from the blood center about it. Initially I determined it would be too risky to give blood during a prolonged fast, (as it could worsen various potential symptoms), and if I did it in the early stages it could derail my plans.
But a few days later, feeling as well as I was in general, I gradually warmed up to the idea. I made an appointment for the 10th and final day of my fast. At the center, on a whim I switched from a regular donation to a "double RBC", or double donation (which I've never done before, fasting or otherwise). I tolerated the donation well enough, just feeling cold but never lightheaded. But from that point on I did feel fatigued, and my heart rate became more easily elevated with activity. Those are totally normal symptoms after such a donation, but with 10 days of fasting on top of that....
So, all-in-all, blood donations are not really recommended during a long fast, especially not double donations. Shocker, I know. I don't really regret doing it, but I would do a normal donation, rather than double, if I had it to do over again.
Jet Lag
I came off the night shift about a week before starting this fast, so my circadian rhythm was still adjusting. It wasn't the smoothest sleep transition, so I still felt kinda groggy for about the first two-three days of this fast. After that I was fine.
Summary and Key Points
Let me explain. No, there is too much. Let me sum up.
Fasting was normal for humans to do for thousands (if you don't believe humans developed through evolution) or even millions (if you do) of years. Only in the past 50-100 years have we had things like grocery stores and refrigerators that made food readily and constantly available. Our ancestors for many generations were accustomed to fasting out of necessity for varying lengths of time, and if their bodies knew how to do it, so do ours.
Fasting is normal. And not only is is normal, it appears to be the only way to access certain healing and regeneration mechanisms, such as autophagy, and regeneration of the immune system (which can heal or at least improve many autoimmune conditions) and other organ systems. It's also likely the best available weapon again obesity, diabetes, and even cancer, not to mention heart disease. Many people have eliminated signs and symptoms of diabetes through fasting, as described in this new book, and studies have shown that cancer cells become easier to kill when fasting, resulting in more effective treatment with chemotherapy or radiation (as well as fewer side-effects). That's to say nothing of fasting helping to prevent cancer in the first place.
I could go on. And on.
If you're interested in the evidence in favor of fasting's health benefits, there is plenty to go around, and it's a lot more compelling than any counterarguments I've heard (which are typically steeped in the flawed nutritional dogma of the past few decades while ignoring most of the actual evidence and millennia of human history).
However, though fasting was the norm till just a couple generations ago, many people have never gone more than a few hours without food in their lives and can scarcely imagine doing so. That is our culture, that's how we grew up, and it doesn't help that misguided dieticians (among others) continue to recommend "small frequent meals" even to the people who would benefit the most from eating less frequently (such as the obese or diabetic).
So, here we are with an incredibly powerful beneficial practice known to humans for millennia and practiced both intentionally and out of necessity for countless generations prior to ours. Now that same practice, fasting, has been largely abandoned due to a few decades of misguided dietary advice and a culture of constant food. And by no small coincidence, now everybody is getting fat and sick (though refined sugar wants to claim its credit for that too).
Fasting isn't easy at first if you've never done it before. Just like running a 5K would be hard if you've literally been sedentary your whole life and don't prepare in any way. It's basically the same. Start doing something different with your body out of the blue and you'll likely struggle.
So start slow and give your body time to adapt, as mine has over the past year-and-a-half. I wrote here (under "Conclusions") about how to ease into it: basically start with time-restricted eating and/or eliminating refined sugar and other refined carbs for a time. That's like the warmups and short training runs you might do leading up to your first-ever 5K. After that, try some water fasts of 24 hours at a time, and then later for 36 hours. After a while the sky's the limit.
And as I've learned gradually--dramatically of late--getting enough of the right electrolytes, especially sodium, can make a prolonged fast much more comfortable than it might be otherwise. Not only comfortable, even euphoric.
Let the fasting begin. Now you'll excuse me while I go eat lunch...
Photos: Breaking the Fast
 |
| My first meal |
 |
| A more substantial meal about an hour later (I had seconds, and thirds) |
 |
| Lunch on the same day (I didn't eat dinner) |
BONUS SECTIONS: Results, Food List, Resources
Specific Results of my 258-hour (10.5 day) Fast
I've already talked about how I felt during this most recent fast, but here are some specific stats (and below are images with my detailed daily notes):
- Weight lost: officially 10 pounds, but more if you consider the additional 4-5 pounds I dropped on the scale during the preceding 2.5 "transition" days mention in the notes (during which my "eating window" was less than an hour each day).
- Blood sugar/glucose levels: Trending down fairly steadily from the 80's to the 50's and even 40's (though there is obviously daily fluctuation with many variables).
- Ketones: Medium - high on urine measurements after a few days and then pretty steady. Urine testing is subject to error, however, and the breathalyzer I got near the end of the 10 days had me at the maximum measurable amount continuously until I broke the fast.
- Energy intake: About 100 cal / day with a little variation.
- Salt Intake: about 3 - 10 grams / day.
"Food" List
A few people at different times have asked what I consume while fasting. The list below many not be exhaustive, but gives a pretty good idea about what I've tried.
Of note, on my first prolonged fast I intentionally ate about 200 cal / day with a high protein content. Since then I've decided that's counterproductive, and I tried to keep my calories as low as reasonably possible during the next two extended fasts. On the most recent fast, however, my calories were a little higher than before, for two main reasons:
- The food-stuffs I was eating were essentially vehicles for sodium/salt -- it's hard to just drink a bunch of salt water or eat it by the spoonful, and the other products made the salt more palatable.
- After my last long fast my stomach felt a bit contracted, as though I'd had a bariatric surgery. This gradually wore off, but in an attempt to avoid the same sensation I included more solids this time (such as dill pickles--things that were still very low-calorie and high in sodium) and tried to really expand my stomach at least once a day. This time, after two days of eating so far, I don't feel quite as much like someone who just got their stomach stapled.
- Water
- Tea, often with a splash of lemon juice (zero cal)
- Potassium supplements (tablets, and later powder)
- Magnesium supplements (capsules, and also Epsom Salt baths)
- Salt (on the tongue, in water, or added to any of the items below)
- Bouillon (about 5-10 cal / serving depending on the type, ~800mg sodium)
- Veggie Broth (5 cal / serving, ~800mg sodium)
- Chicken Stock (~10 cal / serving, ~800mg sodium)
- Sugarless gum (artificial sweeteners are generally to be avoided, but I've made exceptions)
- Vitamin pills and similar supplements (not all the time, only took one or two multivitamins during most recent fast)
- Dill pickles (5 cal / serving, 290mg sodium)
- Sliced jalapeños (from a jar, 5 cal / serving)
- Banana peppers (from a jar, 10 cal / serving)
- Green chiles (from a can, 5 cal / serving)
- Chia seeds (kind of a "cheat"; 60 cal / tablespoon)
As noted, I ate some other proteinacious things on my first five-day fast that I haven't used since, so I saw no reason to include them here.
Resources to Learn More
Without going too crazy (hit me up if you want more), here are a few simple resources I'd recommend for beginners:
Books
- The Obesity Code, by Dr. Jason Fung
- The Obesity Code Podcast
- Fasting Talk
- Found my Fitness (epidodes with Valter Longo, Guido Kroemer, and Satchin Panda)
- Stem-talk (episode with Mark Mattson, any other episodes related to nutrition)
