READING TIME: 23 minutes, or just about the time it takes the entire grit eating world to make grits.

SUMMARY: Fasting has become popular in recent years and many claims have been made about its benefits. However, there are two issues. First, “fasting” comes in many forms— intermittent fasting, water-only fasting, time-restricted eating. We need to be specific about what kind of fasting we mean. Second, many claims have been made about each form, but which of these claims are scientific and which are merely story? And even of the scientific— which are based on substantial evidence in humans, and which are hopeful speculation? In short, what do we actually know about fasting?

1. TrueNorth

THE TRUENORTH HEALTH CENTER WAS NOT AT ALL WHAT I EXPECTED.

Given its status as the premier water-only, medically-operated fasting facility in the country (and one of the only such places in the world), you’d think one would at least be able to recognize the building. But its façade was no more distinctive than a brick bursar’s building in a midwestern college town. Hidden on a tree-lined street in northeastern Santa Rosa, the building was so unremarkable, that my Lyft driver twice drove past the anonymous entrance before, finally, giving in to the GPS’s insistence that we’d in fact reached our destination. Exiting the car, sizing up the property, I was Lloyd Christmas staring into the supposed rocky landscape Colorado: that John Denver’s full of shit.

Its paltry look made me uneasy. I started to feel like an unenviable character in a dystopian movie. The kind where, after one enters this sort of building, they come out different, if at all. And this ominous scene only confirmed the pre-trip whisperings I’d read about TrueNorth and its vegan, evangelistic cult-like vibe. In just minutes, my book-by-the-cover instincts had morphed excitement into pessimism.

Finally, after a few minutes of unanswered doorbell rings, a kindly woman came to let me in. Her big smile seemed genuine enough and temporarily restored my nerves. Michelle was petite but muscular with a peppy personality. I got the feeling she must double as a spin instructor. She led me to her office to sign papers and check in. To get there we walked along the inner perimeter of the a quaint courtyard surrounded by the two-story motel-like building in which the TrueNorth “patients”[1] reside. There I saw people lounging on chairs, some on the ledge of a small fountain, reading and chatting, awaiting supper. Maybe this place wasn’t so bad after all.

Back in Michelle’s office, she explained what would be my basic regimen for the next 6-7 days. A lot of laying around, daily nurse and doctor check-ups, and, of course, not eating.  The intake ended by sorting out finances, reminding me that I was spending almost two thousand dollars to suffer. I quickly mourned the far more appetizing opportunities I was forsaking with my signature— Aspen, Paris, Tokyo. Better food for sure— or at least more of it. But, alas, I was already pot-committed. I signed and sealed my week-long, foodless fate.

Speaking of food, I had perfectly timed my arrival to catch the latter half of dinner. And it was a good thing too, because it would be my last meal for about 100+ hours. I was about to take part in the ancient tradition of fasting.

2. A Good Track Record

Humans have been fasting for centuries.

Herodotus—history’s first real historian— writing in 5^th century BC, noted that the ancient Egyptians felt fasting was the key to restoring health. “They think that all the diseases which exist are produced in men by the food on which they live.” Hippocrates, famously urged us to let “food be thy medicine.” But that’s only the beginning of the quote. It ends with a nod towards fasting: “but to eat when you are sick, is to feed your sickness.”

And almost every religion has traditions of fasting. The Jews have Yom Kippur, in which the fast is meant for a form of repentance. The scholar and physician Maimonides was an apparent proponent of fasting. In Islam, the month of Ramadan is a time for the fast. Rumi, the 13^th century Persian poet said: “there is a certain sweetness in the stomach’s emptiness…when you fast, good habits gather like friends who want to help.” And the Hindus fast on a monthly basis, with the days changing depending on the which sect one follows. Mahatma Gandhi used to fast for all kinds of reasons: his experiments with diet, as a self-directed symbol of restraint, as an outward display of civil disobedience. In ”A Guide To Health”, he wrote: “Illness or disease is only Nature’s warning that filth has accumulated in some portion or other of the body; and it would surely be the part of wisdom to allow Nature to remove the filth.” Fasting, he thought, would help rid us of this “filth.”

But what does this tell us about its actual effectiveness?

Sometimes, having a long history is a good indication of effectiveness. In his book Antifragile, investor and writer Nassim Taleb cites the virtues of foods, investment tools, and technologies that have been in existence for at least 1000 years. Citing the “Lindy Effect,” Taleb argues that these enduring mechanisms are more likely than newer inventions to live on as their “fitness has been tested.”

But, paradoxically, just as longevity can indicate merit, this “antifragility” can also be an indication of a stubborn, but ineffective, tradition. A thing we do, not because we know it works, but just because it is how we’ve always done it. You only have to go back to the mid-20^th century to see the end of the near three-thousand-year rein of the bloodletting, for example. That strange, vampiric practice whose use is agreed to have contributed more harm than good.

So what about fasting? Is it a time-tested principle or a senseless old relic that refuses to die?

It turns out, it may be a little of both. In fact, it may be that the fasting itself is not as important as the diet you return to after you break the fast.

That was certainly part of TrueNorth’s position.

3. The Refeed

DINNER AT TRUENORTH IS SERVED AT 5PM.

The cuisine is a special version of vegan— what’s known as whole-food, plant-based SOS. The “whole-food, plant-based” part means that all of the food is based on whole plants— tomatoes, lettuces, corn, beans, whole grains— as opposed to either animal products (meat, dairy, fish, eggs) or processed foods (granola bars). The “SOS” means that no sugar, oil, or salt are added to any of the foods. So the food here is not cooked on a pan with oil, but water, vinegar, or nothing. To most people, this cuisine must sound about as appetizing as the kosher meal in United coach. Given my usual diet, however, I was, much more enthused.

The buffet line started with huge bowls of colorful salads. Next to that were all sorts of veggies, fruits, beans, nuts and seeds. Wrap around the corner to the hot foods and you’d find all manner of steaming stews, soups, roasted veggies. Perhaps this evening it was a curried lentil stew, a hotpot of mixed whole grains like brown rice and quinoa, a sizzling pan of roasted cauliflower, squash, and eggplant, and, god-willing— my absolute favorite, baked sweet potatoes with tahini on the side. You polish off the meal with as much fresh, Californian fruit as you can hold in your stomach— melons, apples, berries, mango. I filled my plate and bowl with as many plants as I could fit on them. After all, this was going to be my last meal for the next 100+ hours.

WITH NO HANDS LEFT FOR THE DOOR, I turned around, and pulled off the butt-first opening into the court yard. There, I found a seat with a group of people much to my senior, who were already deep in conversation.

I hope I’m not interrupting here. No, they assured me, they were just talking about Hal (who was standing off to my right) and how he had just wrapped up his 40 day fast. 40 days?! Yup, lost over 60 pounds. That’s insane, I thought. What would drive someone to do that? Who is this guy, Jesus? Is that even possible? I would later learn that just early that year, Hal had been diagnosed with cancer. A cancer, he’d hoped (and was presumably told), that would be diminished by the long-term absence of eating.

The remaining couple at the table were the Glatzers. They would turn out to be my friends, adopted parents really, for the remainder of my stay. Mr. G is a war veteran who told stories of Vietnam and meeting John McCain. Mrs. G had some major health challenges she was trying to overcome with the combination of fasting and a plant-based diet. She was hoping it would rid her of diabetic condition and allow her to start walking again. They were both so invested that they started a plant-based supper club where they lived in Sun City, a quiet community in Hilton Head, South Carolina. The membership had already grown to over 600 people. I was inspired. I wanted to join.

So what are you in for?, Mr. G asked in that avuncular way, with a silly sincerity. I was embarrassed to say. I mean, I was a healthy 33 year old, with no conditions, symptoms, or even extra weight. Nothing like the life-threatening ailments that most people come here looking to heal. I was simply there, I eventually told them, to learn about and experience fasting. And part of me was hoping that the bigger benefits of fasting would be borne out by the science. Those promises of “cell autophagy” and stem-cell production— the cleaning out of the body. Rejuvenation. Gilgamesh’s elusive fountain of youth.

I finished my meal, bid the warm couple a good evening, and headed out into the cool Californian evening for an exploratory walk.

BEHIND TRUENORTH LIES a storybook town square. It’s only about a mile outside of Santa Rosa proper, but even so this tiny community is a separate, self-sustaining entity. It’s the kind of square that has one of everything. There’s the one bustling café, the boutique fitness centers and yoga studios, the specialty supermarket, and the Italian wine bar. All of which is nestled in between a quiet, sunny labyrinth of Californian cottages—well-designed abodes, not too big or grand, but designed in such a way, that one prefers them. They’re not so much houses as they are homes.

As I meandered through town, looking at the people laughing and drinking their wine, the summer sun sinking in the western sky, I started to reevaluate why I was there. Was this really a good use of my time and money? Is the science on fasting far enough a long to warrant this kind of effort?

I got back to my room with thoughts swirling through my mind. I quickly took a shower, sat on my bed, and pulled out my laptop. I opened articles and lectures I had saved, took out the couple books I had about fasting, and started to dig.

What did we really know about fasting?

4. The Science

THERE SEEM TO BE TWO PRIMARY REASONS that someone would decide to fast (outside of the religious context). And each of these two goals come with key questions surrounding the science.

(1) The Weight Loss Goal. This goal is to improve “metabolic factors”— weight, blood pressure, insulin resistance, cholesterol.

• Key Questions: Is fasting more effective than other forms of dieting long-term? Is it easier or harder to sustain? Is it safe?

(2) The Longevity Goal. The more ambitious, longevity-based goals of cell cleansing (“autophagy”) and rejuvenation (stem-cell production).

• Key Questions: Does fasting activate these processes in humans? If so, how and when? And do these processes work to mitigate, halt, or even reverse human disease, cancer or aging?

Let’s start with the easier topic— fasting for weight loss.

Fasting For Weight-Loss

At the outset, we can do away with the obvious: if you eat nothing, you are going to lose weight.

It takes a lot of energy just to keep us operating — roughly 300-500 calories per day for the brain alone. So if you’re not providing that from without, the body will start to consume from within. In other words, if you starve yourself, you will definitely lose weight, and quickly. This could be 5 to 10 to 40 pounds or more within a week or so, depending on your size.

But the key question is if there is any lasting effect. If I fast for a period of one week, for instance, will I be healthier, lighter, with lower blood pressure, lower cholesterol once I stop fasting? And how long will this last for? Or, will all of my ailments come rushing back to me once I inevitably return to the gorge?

In addition to Hal, the Bible-style, 40-day faster trying to starve his cancer, many people at TrueNorth had already lost upwards of 30-40 pounds in just weeks. They’d come in, desperate to find an answer to their chronic, seemingly lifestyle-related conditions: type II diabetes, insanely high blood pressure and cholesterol, recent histories of severe heart trouble. They go on a fast for 5 or 10 or even 30 days at a time and the pounds melted off.

But what will happen after? When they go back to their real lives, will the mere fact of having fasted result in a healthier body?

The answer: it’s not so clear.

On the one hand, a periodic fast from anywhere between 4-5 days and 20 days has shown benefit one year later. And these were health benefits across the board: weight, blood pressure, blood-glucose, well-being. All from just fasting for about one week of that year.

The problem is that many diets work for 6 to 12 to even 18 months. But the key problem is sustaining past this honeymoon phase. What about long term?

A study to this effect was initiated nearly 50 years ago. People were put on a fasting diet for periods differing in length for up to two months. The patients were able to maintain, on average, about half of their ~50 lbs of weight loss for up to 12-18 months following the fast. But then, upon the check in 7 years later, nearly all of the participants (over 200) had gained back nearly all of the weight (all by 7).

But that’s 1970s science. What about something more recent?

In a 2014 study, researchers split patients into two groups – one on a modified fasting diet (occasional broths equalling ~200 calories/day) for 5-10 days, the other 200 patients on a calorie restricted (~300-500 calories less than normal) low-fat, whole-food diet, the patients were measured in all kinds of ways, and then went home after 20 days. Then, the participants were followed up with seven years later. Here’s what happened.

The fasting group lost more weight during the 20 day inpatient stay— about double at 17.5 pounds on average versus the diet group at around 8.5 lbs. But, at the time of the interviews seven years later, only about 10% of the fasting group had maintained just 5% body weight loss, where as over 30% of the diet group did.  And on average, the fasting group had gained weight.

Crucially, the researchers noted that:

“A prevailing proportion of patients with successful weight reduction could only be detected in the group of study participants who had changed their nutrition for the whole observation period.”

In other words— fasting only “worked” if people actually started to eat healthier after the fact.

But the question is, if it’s potentially just as effective for weight loss (as long as you eat healthy when you return), what’s the harm in trying it? Maybe you’d like it better.

There are two problems: (1) fasting might cut weight, but it might be the wrong kind of weight and (2) long-term fasting (three or more days) probably isn’t that safe. At least not without medical supervision. 

First on safety. There are many things that could go wrong when you fast—- low blood sugar, electrolyte deficiency, vitamin and mineral deficiency, heart issues. And many of these conditions often come about in “nonspecific” symptoms— nausea, dizziness, headaches, that wouldn’t necessarily tip you off that something seriously wrong could be mounting. Many of these conditions, unchecked, could lead to fainting, brain damage, or even death. So medical supervision is required.

But even when in terms of weight loss, what kind of weight are we losing? We are probably not interested in cutting anything other than fat, right?  It appears that fasting might actually slow down the rate of fat loss.

Interestingly, this might be the case with the Keto diet as well, and for similar reasons. When you fast, your body has no glycogen to use (the body’s default fuel), so it turns to ketones. This sounds like a good thing, since ketones are produced by converting fatty acids to energy your body can use. But what ends up happening, as suggested in an old study, and confirmed in a more recent study (funded by the pro-keto writer Gary Taubes) ketosis slowed fat-loss.

So, what we have is a potentially ineffective, potentially risky process that is also by nature not sustainable (you can’t just not eat forever).

So what are we to conclude? That if you’re primary interest in fasting is long-term weight loss, it isn’t a good ideas? Well, not necessarily. There may be a benefit. But interestingly, that benefit might be more psychological than physical.

AT TRUENORTH, THEY ARE certainly big proponents of water-only, long-term fasts, but that’s not the entire message.The other half of the message at TrueNorth is about what you do after the fast.

You’re going to need to eat some food at some point, of course. So your post-fasting diet heavily impacts overall fasting success.

On a weekly basis, TrueNorth holds lectures given by all manner of professionals: PhDs, doctors, therapists, fitness specialists, dieticians. The messages from these people are two-fold. (1) Use fasting as a tool, but only as a “jump start” to weight-loss. (2) After that, and more importantly, you need to adopt a healthy lifestyle. That begins, they believe, on a whole-food, plant-based SOS diet.

The biggest feather in the fasting cap, then, comes not in the initial weight, and maybe not in the other claims, but in the perspective shift. After you fast, you change how you view food, how much or how often you need to eat. And you also have a shift about yourself. You develop some belief in yourself— what famed psychologist, Albert Bandura, called, “self-efficacy”— the belief that you can do more than you thought.

Let’s recap.

The argument from fasting proponents seems to be as follows:

1. The fast itself has lasting weight-loss and metabolic benefits
2. it will change your relationship to food, showing you that you don’t need as much as you thought
3. It will change your relationship to yourself— it shows you a kind of “self-efficacy.” I am more resilient than I thought
4. Because of these two qualities, you’ll have an easier time adopting new eating habits— preferably with a lot more salt-,oil-, and sugar-free plants.
5. All of that together will fight off disease, cancer, and even replenish and rejuvenate cellular production via stem-cells.

We’ve taken a look at the first four: (1) seems still unclear and (5) I’ll get into next time. For (2), (3) and (4), they seem to be reasonable assertions, but not well-studied.

Perhaps my experience can offer an “n = 1” anecdote…

5. My Experience

Day 3. 37 hours into the fast. Weight: 159.7, about 3.5 lbs down since arriving.  

I still felt more or less normal.

But then, I’d done a couple 1-2 day fasts in years past, so nothing was that new to me yet. I went though the regular routine of a TrueNorth patient.

First, we need to capture a urine specimen. I aimed, with varying accuracy, into a small jar labeled with my name. This always reminds me of that carnival water target game where your accuracy moves your horse in a race. In this race, my horse was definitely losing. I was to put the jar into the fridge so that my urine could be evaluated for one of the tens of irregularities that might spring up during a fast. I then waited for the nurse to come around to take my blood pressure and interrogate me, searching for signs of concern. Nurse satisfied, I headed out the door for a long, but noticeably slow morning walk.  

IT WASN’T UNTIL LATER THAT AFTERNOON, about 44 hours into the fast, that weakness and lethargy started to creep in. It was at the regular downtime of the day, around 2:30 or 3PM, so I attributed some of the effects to typical tiredness. But there was something more. Almost like a slightly depression. Every movement started to feel more effortful.

This became most pronounced in the late morning of day 4, 60 or so hours in. I was at 158, my lowest  weight in 17 years, and I could barely move. Interestingly, it wasn’t hunger that was plaguing me, but a complete lack of energy or motivation. Usually a peppy, ready-to-go, early-riser, I emerged from my bed sulky. Even descending the ten stairs to the courtyard required abnormal concentration.

I walked into and through the town as though in someone else’s body. Moving at a pace that felt more like my body was moving me, I started to wonder if I should be walking at all. I was merely leaning forward slightly, catching myself in tiny, calculated steps, as if I moving with my gas light on, hoping to find a filling station in the next hundred yards.

It became clear in the midst of this stilted motion why fasting over two days is said to be very dangerous without medical supervision. Here I was, a relatively in-shape, healthy 33 year old with no known conditions, and I was reduced to mere effortful existence. Think what it must be like for a 55 year old with a rap sheet of ailments and carrying sixty or seventy extra pounds.

I was only walking to keep up some semblance of regular life and thinking. But, it should be said, that TrueNorth discourages a lot of movement during the fast. This mandate to conserve energy is so pronounced, that they even advise against showering because of the energy your body has to expend just to maintain homeostasis— sweat to cool you down, shivering to restore warmth at shower’s end.

I stumbled back to my room for an afternoon nap.

Later in DAY 4, golden-hour, odd euphoria.

We now come to the most interesting part. At about 70 hours, I caught a second wind.

All of a sudden, I had energy to read and write again. I felt motivated, even excited. I felt like I could go perform a workout (something from which I was discouraged after a fast walk). This actually freighted me a bit.

What was happening?

It turns out, this was expected. Often referred to as the “fasting high,” it’s a similar feeling once you reach ketosis. Apparently, my body had started burning ketones, and my brain had told me to be motivated and happy. Mostly, it is thought, this is to inspire one to go find some food, hopefully glucose-rich. But whatever the explanation, I didn’t have any problems from then on. I could easily see how people might fast for 10 or 20 days at that rate.

Day 6, day of the breakfast, 110 hours in. Weight: 154.2. Total weight loss: ~9 lbs in 4.5 days.  

I broke the fast at around 10am in the morning, 4.5 days into the fast. (The timing was on purpose, I’ll explain why below).

Paradoxically, it is apparently this time— the time of returning to eating— that is the most dangerous for fasters. Overeating (especially the wrong foods) at this point can send your body into shock and cause heart, digestive, or brain trauma, even sudden death. It has come to be known as “Refeeding Syndrome.”

I returned to the eating world with a fruit and vegetable juice. I think it was lots of greens, root veggies— carrot, beet— some citrus fruits, and watermelon. Delish! Nothing ever tasted so good. I tried with all of my might to drink as slow as possible. Both to savor the flavor, and to, you know, not go into cardiac arrest.

So why 4.5 days?

Well, again, I was not there for the 9lbs of weight loss. I knew that as soon as I returned to my normal eating, say over the next 1-2 weeks, I would regain all of that weight. And I wasn’t really there to change my perspective about food— I already ate a whole-food, plant-based diet, very little salt, very little sugar, very little oils added. (Though, fasting did add to my sense of resilience and self-efficacy).

The reason I was there were for the second reason— the Longevity Goal. I was there because of the possibility of cell autophagy, stem cell production, and a host of other purported benefits at the cellular level. Apparently, the minimum effective dose for those kinds of benefits is somewhere around the four day mark.

So did that happen? Was I producing stem-cells? Was I going to live forever? We’ll, that, it turns out is no so clear either. I’ll discuss next week.

AFTER GETTING TO TASTE real food again the next morning— a big bowl of oatmeal, nuts, seeds, fruit, and steamed veggies— I was packing up my things. As part of the price of admission, a nice benefit is that they will give you up to 2-3 meals to go. Given how much I like the food, I was VERY excited about that, and I would later eat almost that whole 2-3 meal worth in Duboce Park, San Francisco, with my best friend, Jason and his fiancé, just a few hours later.

I said some good byes to people I’d met: Scott (a cancer survivor we’ll meet next time), Hal, and of course, the Glatzers.

I had just been there a short stay, but they were to stay for weeks on end. I was slightly jealous. I promised them I’d be in touch, and that hopefully I’d make my way over to Hilton Head in the near future.

Things packed, meals wrapped up, I got a phone call from a Santa Rosa number. It was my Lyft driver.

“Hey, Justin?”

“Yep – that’s me.”

“This is your driver. It says I’m here, but I don’t see an entrance.”

I smirked: best-kept secret. “Yea, I know. It’s confusing, right? I’ll be right out.”

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[1] I put patients in quotes because I’m not sure whether a better word here might be customer than patient. A patient is someone who goes to a consensus medical facility. TrueNorth is more like a fringe wellness retreat