Yesterday’s run was done fasted, and at a slightly faster pace than my usual, both with an eye toward burning some carbs ahead of having pancakes with maple syrup for breakfast after. 🏃🏻♂️ (Today I’m fasting for a blood draw ahead of an upcoming physical.)
Fasting is very much in the forefront of the kooky part of the health/wellness/fitness world that has me snake-fascinated. I’m convinced by the basic logic that our physiology functions best when we alternate between fed and fasted states, and functions poorly when we are always in a fed state.
As I write this, I’m approaching the end of a three-day fast. I did similar fasts in 2018 and 2019. This is actually my 2020 fast, slipped to early 2021 because I’d hesitated to do a fast during a pandemic. The pandemic isn’t over, but with 11 months of experience at dealing with it, I knew I could just arrange my schedule such that I had virtually no contact with other people for these three days.
There are a lot of ways to do a fast, differing primarily in how long one fasts, and also in what one consumes during the fast.
At one end of the spectrum there’s just not eating for the period between supper and breakfast, which pretty easily stretches to 12 hours for anyone who can forego a bedtime or midnight snack. That period can be extended moderately—there are people who chose to fast for 13 to 16 hours per day—or it can be extended by somewhat more—some people choose to fast for a whole day. At the other end of the spectrum there’s prolonged fasting, where people fast for multiple days.
There are names for these various protocols. Some people practice what’s called 16:8 fasting, where they fast for 16 hours out of the day and consume all the food they eat within an 8 hour window (perhaps 8:00 AM to 4:00 PM, or noon to 8:00 PM). Another is called 5:2 fasting, where people fast on two days out of a week, eating as they like on the other five.
People seem to use the term “time-restricted eating” (or time-restricted feeding, if you’re talking about lab animals) to refer to fasting protocols where the fasting/eating windows are measured in hours. There is also the term “intermittent fasting” which some people just use as a generic term to refer to fasting protocols where the fasting window is not much more than a full day. (If you fast on alternate days you’ll typically end up with 36-hour fasts, assuming that you start your fast after supper on day 1, fast on day 2, and then break your fast with breakfast on day 3.)
Beyond the numerous periods of intermittent fasting, there’s the broad category of “prolonged fasting,” which can be anything from 48 hours out to 30 days or more, although fasting for longer than a week is rarely done for health reasons, except for people who are morbidly obese.
I’ve become convinced that some amount of fasting is not only healthy, it is important for health. Very briefly, there’s a finely balanced system inside of each cell that monitors available energy and available amino acids. If those things are present, the cell switches into a growth pathway, and starts making proteins and organelles (whatever the cell needs at the time). If the cell is short of either energy or amino acids, it switches over into what’s called autophagy, and instead of making proteins starts breaking them down.
For many people in the modern world it has become ordinary to eat frequently enough that one rarely goes even as long as 12 hours without eating. In that circumstance, cells rarely ever switch out of the growth pathway. Autophagy never happens, and old proteins never get broken down. This leads to all sorts of problems. Clearing out those damaged proteins (and damaged organelles) is important—they’re implicated in virtually all the diseases of aging from cancer to Alzheimer’s.
The cell seems to preferentially break down damaged, mis-folded proteins and damaged organelles. (See Selective degradation of mitochondria by mitophagy.) In any case, it’s going to replace them with whatever proteins and organelles you need most at the current moment. The process will end up improving both the quality and appropriateness of your cellular machinery.
I do a version of intermittent fasting all the time. Jackie and I eat breakfast fairly early in the morning, but then we just have one main meal of the day, usually around 2:00 PM. We got started on that because I found that eating close to bedtime was interfering with my sleep, and Jackie got frustrated that moving supper as early as I wanted meant that there was barely enough time between lunch and supper to clean up the kitchen and then prepare another meal. My proposal to just combine the two meals was met with some initial skepticism, but it has turned out to suit us very well.
In one sense, I’m doing a version of a 16:8 fast, because I fast from 3:00 PM or so until 7:00 AM the next morning. It’s not a strict fast though. I typically have cocktail hour at 4:00 PM, and I nearly always have cream in my coffee first thing when I get up in the morning. That shrinks the window in which I’m strictly fasting, but probably does it in a way that doesn’t much reduce the benefits of the fast. (For details see Fast This Way, by Dave Asprey the guy who invented Bulletproof coffee.)
Once a year though, I do a prolonged fast of at least three days. Although the research is preliminary, there’s some evidence that after three days the body goes beyond just autophagy, and starts clearing out senescent cells. That’s great, if it’s true; there’s very good evidence that clearing out senescent cells substantially improves healthspan and lifespan.
Except that I have a big cup of green tea in the morning (mainly to support my caffeine habit, also because green tea boosts autophagy and ketone production), I’m doing a water-only fast.
It hasn’t been hard. I was a little hungry the first day, felt great the second, and am now rather looking forward to breaking my fast in a few hours. But if there were some reason to extend my fast I could do it easily enough.
I made a point of getting in a hard lifting session on day two, just to let my body know that I was most definitely using those muscles, and that those proteins should be used to repair muscle and not be metabolized for energy.
For a couple of years now I’ve been experimenting with time-restricted eating.
I guess I really started about a year and a half ago, after I got my Oura ring. One of the first things I noticed was that the early hours of my sleep were disrupted unless I had finished dinner at least 4 hours before bedtime. (This in contrast to the “common wisdom” that you want at least three hours between the last thing you eat and bedtime.)
Once I notice that I started pushing Jackie to arrange things so that we could finish supper at least 4 hours before we went to bed. The issue here was that while working at the bakery Jackie had gotten into the habit of getting up at 4:00 AM—because that’s when she needed to get up if she was going to be able to have coffee, breakfast, dress for work, and then spend most of an hour walking to work. As she has been so far unable to break herself of that habit, she finds herself very sleepy starting at about 8:00 PM. If you work out the math, you can see that we need to finish supper no later than 4:00 PM.
Jackie found herself somewhat daunted by the prospect of having to prepare lunch at mid-day, clean up the kitchen, and then prepare supper to serve at 3:00 PM so we could be done by 4:00 PM.
We experimented with various lunch/supper timings with limited success. But back in December, when Steven brought Lucy and his boys to visit, we fell into the habit of just having two meals a day. I went to his hotel for the breakfast that the hotel served to guests (Jackie made her usual breakfast at home), and then one of us (often, but not always, Jackie) prepared our main meal of the day sometime in the afternoon.
This turned out to work great, and Jackie and I have continued the practice since Steven and family departed. Jackie gets up at 4:00 AM as usual. (I tend to sleep until closer to 6:00 AM.) We linger over coffee, then have breakfast at 7:00 AM or so. Whatever we hope to get done in the day happens between 8:00 AM and 2:00 PM, at which point we have “dinner” consisting of our main meal of the day. We finish it by 3:00 PM or so.
(In these pandemic days we follow that up with a virtual happy hour with Steven and Lucy via Zoom, so we’re still consuming cocktails until 4:30 PM or so, but I try to make sure to limit both the carbs and the calories that late in the day. I’m hoping that eventually we’ll be able to arrange things such that happy hour doesn’t extended until so close to bedtime.)
Jackie and I usually enjoy some video entertainment in the evening, and then retire to read for a bit before 8:00 PM and time to go to sleep.
I’m sure that’s way more detail than a stranger could be interested in, but the gist is that our eating window is compressed to just 9 hours a day or so (from 7:00 AM until 4:00 PM), putting us within striking distance of a 16:8 time-restricted eating window.
And I have to say, it’s working pretty well. Jackie especially appreciates not having to prepare both lunch and dinner every day. Keeping my weight stable has been especially easy—if I’m hungry in the morning I fix a bigger omelette, if I’m hungry at mid-day I take a bigger serving of whatever Jackie is fixing, or just have something more (peanut butter, cottage cheese, jerky, protein powder, whatever). And if I’m not extra hungry, I just eat a regular breakfast and a regular mid-day meal.
The result has been that I easily get enough food, don’t overeat, get done eating four hours before bedtime, and spend nearly 16 hours per day in a fasted state, with all the attendant benefits described in the post linked just above. And as a bonus, Jackie doesn’t have to prepare two meals after breakfast.
Time-restricted eating: Highly recommended.
When you feel sick, you prefer to sit still. This behavior pattern is not only well known, it even has a name: “inflammatory-induced sickness behavior.”
In the modern world this easily leads to a particularly pernicious vicious cycle. Modern lifestyles lead to metabolic syndrome. Metabolic syndrome produces systemic inflammation, which makes you feel like sitting still. Wanting to sit still makes what would otherwise be the most potent tool for reducing systemic inflammation—exercise—tough to bring to bear.
This rather dense article from back in 2010 describes the problem: Inflammatory modulation of exercise salience: using hormesis to return to a healthy lifestyle. It also proposes a category of solutions: hormesis. That is to say, any of a set of mild metabolic stresses that prompt a response greater than “just enough” to stave off the damage produced by the stress itself.
The result is less systemic inflammation, and therefore less inflammatory-induced sickness behavior, hence an increased inclination to move.
Or, as they say:
We therefore propose that exercise salience, the motivation to undertake physical activity, is modulated by the inflammatory status of an animal, decreasing in an inflammatory phenotype, including the metabolic syndrome and increasing in an anti-inflammatory “healthy” phenotype. The type of phenotype may well be determined by the degree of hormesis, as metabolic stressors, such as exercise, plant polyphenols and calorie restriction tend to induce an anti-inflammatory phenotype.
Besides exercise, the article suggests two other broad categories of available hormetins.
One is related to food, and consists of the obvious stuff that everybody knows: Avoid industrially produced edible substances. Consider such modalities as time-restricted eating, calorie restriction, or fasting. Include foods rich in plant polyphenols. (In other words, “Eat food, not too much, mostly plants.”)
The other is related to temperature: Expose yourself to mild cold and/or heat stress. (Spend time outdoors in the winter. Take a cold shower. Spend time outdoors in the summer. Take a sauna.)
Each of these things will produce some mild metabolic stress. As long as you don’t overdo it, that mild stress will produce a stress response greater than necessary to handle the stress itself, with the side-effect of bringing down systemic inflammation. With the systemic inflammation eased, you’ll start feeling like moving again. That puts the potent tool of exercise back on the table.
Nature has a more recent article on all this stuff, which is sadly behind a paywall.
I have spent a lot of time following the latest research on all sorts of interventions to increase lifespan and healthspan. I am now ready to say that virtually all this time has been wasted.
I guess it hasn’t technically been wasted, in that I’ve come to understand the latest research, and that’s of some value. But when it comes to choosing interventions that might help me, it turns out there’s nothing new beyond the obvious healthy lifestyle recommendations of 20 or even 30 years ago.
There are a bunch of chemical interventions that are interesting—they have definitely been shown to increase healthspan and lifespan in animal models, and have had some very promising results in humans as well. However, it is becoming clear that virtually all of them are either exercise mimetics or fasting mimetics—drugs that activate (some of) the metabolic pathways activated by exercise or fasting.
From a public health perspective, perhaps this is of some interest. Given a population of sedentary people with poor diets it’s easy to foresee a mix of these drugs delaying mortality and morbidity—people will live longer, and during their extended lifespan they’ll have less disability, less illness, and require less medical care.
From my perspective though, it’s completely uninteresting. I would much rather just exercise than take a drug that provides a subset of the benefits of exercise. Similarly, I’d much rather just eat good food than take a drug that simulates some of the effects of doing so.
Do you want to live a long, healthy life? Here’s an plan for you:
That’s it. Unless you are sick with a diagnosed condition for which there is treatment, I very much doubt there is anything modern medicine—or even bleeding-edge longevity research—can do for you that you won’t get from this plan.
I’m sure my brother is very amused that it has taken me this long to come to this conclusion.
Went for a longish run at a nice easy pace. Felt good all the way through—good enough that I was going to add another half mile or so (by running around Dohme Park), only to have my knees abruptly say, “Nope. You have run the correct amount.” So I just stopped right there and came home. As I have started doing lately, I did this run in a fasted state (mumble mumble autophagy, mitophagy).
