In the end I fasted for three and a half days instead of the four-day fast I originally planned. Sure I had to snack a bit, but I think I got the general idea. Here are my thoughts on the experience.

The most remarkable thing was how unremarkable it all was. I didn’t have any trouble going 36 hours without eating. With only a couple of exceptions, I didn’t feel hungry at all. I know that sounds improbable, but it’s true.

The problem I had was headaches. My first one started about 24 hours into my fast and lasted until I had a little food 24 hours later. That’s a long time to have a headache, at least for me. 24 hours after that, my headache started to come back and I couldn’t sleep because I was so hungry. So I had another snack. On the morning of Day 4, I woke up with the beginnings of another strong headache, so I broke my fast.

Jess says I sounded stoned when she talked to me on Monday. Looking back, that sounds about right. I was foggy or a little dazed most of the time. My hands shook in the morning and I felt less coordinated than usual. I got lightheaded easily. It took me a long time to do anything that required moving. But at the time I felt fine. Just in slo-mo.

I didn’t feel lethargic while I was fasting, though. I went for a three-mile hike, and it felt good, although I did go back to my room and doze off afterward. Normally I run 3–7 miles every other day, but that wouldn’t be an option for me while fasting.

The biggest surprise for me was that, for the most part, my stomach didn’t feel empty. Most of the time I actually felt full. I’d heard that ketones (the fuel your body gets from fat while you are fasting) function as appetite suppressants, but I wasn’t expecting them to be quite so effective. I felt hungrier this morning than I did while I was fasting, and I had a hearty dinner last night.

The effects of fasting really became apparent when I ate breakfast yesterday morning. As the food hit my system, I could feel my body’s systems coming back online. It felt like I was waking up for a second time that day. Colors brightened, my mind clicked into focus, and the fog lifted. I don’t want to overstate the moment; it wasn’t profound or anything. But it was pretty cool.

I don’t think I will probably try long-term fasting again. If I am lucky enough to get another chance to spend a few days by myself, I’d like to be able to enjoy them by getting out and doing things. Also I’m just not curious enough to find out what happens if I fast for longer than three days. Fasting wasn’t a bad experience or anything, but I was a little out of it.

But I might try something similar. When I was fasting, my body was burning fat instead of carbs — ketosis, in other words. But you don’t have to fast to enter ketosis. You can do it just by cutting out carbs. And based on my experience, I think I could cruise for days on about 500 calories every evening while in ketosis. That would be just enough calories to give me a little energy boost, help me sleep, and stave off headaches, but not enough to fill me up. Those calories would also have to be mainly from protein and fat, not carbs, so as not to interrupt ketosis. (Once you consume enough carbs, you wind up in glycolysis again, which means you don’t get the appetite-suppressant side effect of ketosis.)

I might try that the next time I am on my own for a few days and can afford not to do much. But it’s pretty hard to be a good dad and husband when I am in a fog and low on energy. I’m not going to try fasting or radical calorie-cutting during my day-to-day life.

So that’s it. This morning I am packing up and heading home to go for a run and then see Jess and the girls. Thanks for reading!

Here are my journal entries from just before and during my fast:

Experiment: Four-Day Fast

I’m not going to eat for four days.

For the second year in a row, I am taking a personal retreat at the St. John’s Abbey Guesthouse. It’s nice to have a few days of quiet to relax, read, and reflect. Plus, CSB/SJU is a special place for me. My parents (and some of my aunts and uncles) were married there. I was baptized there. We lived in a dorm at St. Ben’s when I was a baby, and I bounced in the doorway in my Johnny Jump Up. I remember sitting on Sister Dennis‘s lap at a kick wheel in the pottery when I was 5 or 6 while she showed me how to throw a pot. And I always love sitting and talking with Father Rene. St. John’s feels a bit like home, even though I didn’t go to school there.

I’m not religious in the least, by the way, but I’m glad other people are so that places like St. John’s exist.

Anyway, this year I’m going to fast during my retreat.

I’m not trying to cleanse my body or find enlightenment or any other new-age bullshit. And I’m definitely not trying to identify with the Syrian refugees. I will be staying in a comfortable room at a place I love, with the option to eat any time I want to. I just want to know what it feels like not to eat for several days. I guess I’m just curious. Plus, it will be a challenge, and I like challenges.

My plan is to start fasting this Sunday and break my fast next Thursday morning. I will drink water, tea, and black coffee, but that’s it. No calories. I will try to lower my calorie intake this week so my body gets used to making do with less, but there is a lot of leftover Halloween candy in my house and I have the willpower of an infant when it comes to chocolate.

I hope I’m up for walking and reading, since St. John’s is an excellent place for both of those activities. I don’t plan to do much else except post updates if I have something more interesting to say than SO HUNGRY!!!

Stay tuned if you want to know what comes after hangry.

Fasting Journal, Day 1 of 4

1:30 p.m.

As I understand the science, sometime today or tomorrow my body will switch its energy source from carbs to fat. Glucose, what we normally use for energy, mostly comes from ingested carbohydrates, while ketone bodies, our backup fuel, come from stored fat. There may be a period of glucose “withdrawal” while my body reconfigures to fat-burning mode, but then I should be good to go. Once my body switches to fat-burning mode, other physiological changes will kick in that might be good for me, probably won’t hurt me, and will make me not feel hungry any more.

To help move that process along, I didn’t eat any carbs yesterday and I ate about half the calories I normally do. With fewer carbs in my system before I stopped eating, it should take less time for my body’s glucose stores (glycogen) to drop. When that happens, my body will switch from carb burning (glycolysis) to fat burning (nutritional ketosis). And now I sound like I’m on a hipster diet or something. I blame Tim Ferriss, whose podcast I listened to on the way up to St. John’s. If you want to have the same tenuous understanding of the science as I do, listen to the most recent episode.

So far today, I’ve had four or five cups of coffee, some water, and I’ve taken two short walks. This is the view from my room at the St. John’s Guesthouse, by the way:


It’s impossible not to want to sit next to the window and read. Or gaze. Or go out and walk. Speaking of which, I’ve got a large stack of books calling to me …

3:45 p.m.

I’ve been reading for a while, and my stomach is finally growling. I really want to go upstairs and find a snack. Bad idea, I know. This will pass. I just have to wait it out.

8 p.m.

I expected to feel lethargic after a day of fasting, but I feel fine other than an empty stomach. And the empty stomach isn’t really bothering me. This afternoon, though, I couldn’t stop thinking about food. First I was dreaming about something like bread and pasta. Then I was thinking about meat. When the smells from dinner prep in the kitchen started filling the building, I just wanted to drink some broth. But now I’m feeling okay with not eating.

I feel chilly, but I think it’s just kind of chilly in here. I do have just a little bit of a headache. It’s very mild, but maybe that’s the glucose withdrawal kicking in. My sinuses feel a bit weird. Nothing out of the ordinary with all the leaf mold that’s around, but apparently a weakened immune system is part of glucose withdrawal. I’ll be hiding in my room from anyone who could get me sick.

9:30 p.m.

It’s early, but hey, I’m on my own schedule. I’m turning in.

Fasting Journal, Day 2 of 4

5:30 a.m.

Going to bed at 9:30 does not work for me. I’ve been tossing and turning since about 3:30 this morning, and finally decided I might as well get up. I’m sure fasting doesn’t help, but I think that’s just too much sleep for me.

My stomach feels empty, but it has stopped growling now. My headache has receded, too.

6:30 a.m.

I’m up and showered. The St. John’s Guesthouse isn’t luxurious, but it is very clean and nicely furnished. I particularly like the towel warmer.

I’ve got the weakies. I don’t know what else you call it; that’s what Jess has always called it when you are really hungry, you can’t think well, and you fumble around when trying to do things. I’m not feeling all that hungry, actually. Okay, a little bit, but I think it’s more out of habit than anything else. My day pretty much revolves around when I’m going to eat next. (Or when I’m going to drink my next batch of Soylent.)

It’s breakfast time, now, which means I can finally get coffee. Hopefully that will take care of the weakies.

7:45 a.m.

Pretty sure today is going to be the hard day. I got a post up on Lawyerist, but I’m feeling a bit lightheaded and woozy so I’m going to stay put for a bit and watch a movie or something. (Jess probably just read that and got worried because I have passed out before from getting up too quickly. Don’t worry, Jess, I’ll be careful!)

10:30 a.m.

Feeling pretty run down today. I don’t think it’s anything to worry about, but I’ve been lying down and taking it easy. I had some salt with my coffee and drank some tea fortified with Vitamin C. I still have a mild headache but I don’t want to take Ibuprofen because I definitely don’t need a blood thinner right now.

I keep thinking I’ll go for a walk, but I’m a little woozy so it’s probably not a great idea. The Internet says this is normal during fasting.

My plan is to get more coffee, then do a little of the work I’ve got to get done today.

12:00 p.m.

My headache is full-on, now. I feel like I’ve got a pretty good hangover, and have for a couple of hours. I decided I could probably consume a few calories without violating the spirit of my fast. I drove into town and got some beef bouillon. I mixed it with some butter. It’s maybe a dozen calories, but it tastes like a meal.

I also picked up some supplies in case I need a bit more sustenance later, but hopefully the broth will do the trick.

2 p.m.

The broth helped a bit, but it didn’t make my headache go away. I also went for a walk to try to clear my head, but now I’m back in my room, lying on my bed with my eyes closed.

5 p.m.


I’ve decided that if I still have a headache at 7 p.m., which is about 24 hours from when it started (although it was much milder then), I’m going to break my fast. First without carbs, then with them if I haven’t shaken off the headache within an hour. There’s no reason I should endure a headache for longer than 24 hours.

If I’m able to kick the headache without carbs, I’ll go back to fasting. If I need carbs to kick the headache, I’ll cut my fast short, since that will pull my body back out of fat-burning mode.

5:40 p.m.

Screw it, I’m tired of feeling like this. I ate a can of sardines, which are high in the fatty acids my body is supposed to be burning for fuel right now. They were pretty good. I also ate a can of oysters, which were not very good. Why such random foods? Both were recommended by the physiologist who was a guest on the podcast I listened to on the way up here yesterday.

I would eat canned sardines again. I probably won’t eat canned oysters again.

5:50 p.m.

Wow, that was near-instant relief. Back to fasting, then. I’ve had about 500 calories today, which is not technically fasting but is still pretty crazy low. My recommended intake is something like 2,000–2,500 calories per day.

Since I didn’t eat any carbs, just protein and fat, I should still be burning fat. Hopefully that jump-started the fat burning so I don’t have any more headache problems. If I get another headache in the morning, I will probably just break my fast. No sense feeling like crap the whole time I am up here.

9:20 p.m.

Seriously, that snack hit the spot. I feel great, and hopefully that will carry over to tomorrow even if I stop eating again.

11 p.m.


Fasting Journal, Day 3 of 4

9 a.m.

I slept great. Must have been the sardines. I woke up about 8:20 and stayed in bed checking email and Facebook until just now.

I’m feeling guilty about snacking. What if my headache would have gone away on its own in another hour or two? Yeah, probably not. And that headache had to go. I guess I can only fast with a little bit of snacking.

Off to get coffee and then shower. I think I will do some work this morning and then take a walk around the lake.

1 p.m.

I just hiked 3 miles out to the Stella Maris chapel and back.


I expected to be lethargic from fasting, but I feel pretty good. I’m sure my brain and body are moving a bit slower than usual, but I hiked at a brisk pace and I don’t feel run down at all.

People keep asking me why I am fasting, and my answer — curiosity — doesn’t seem to satisfy them. I guess it doesn’t seem like a good-enough reason to starve for four days.1 I guess I think curiosity is a powerful motivator all on its own, but for those who don’t understand being motivated by curiosity, let me try another angle.

When I was 15, I went on a multi-week Outward Bound trip in the North Carolina wilderness that included a high-ropes course with a huge 60-foot swing. Several people in our group were nervous, and at least one of the girls was terrified of heights. The instructor said they didn’t have to do anything, but challenged them to try. She gathered us around a tree stump and pointed to one of the inner rings. Before starting the trip, she said, most of us had a small comfort zone, like one of the inner rings of that tree. Some started out with larger comfort zones than others, but each new experience — backpacking and camping in the rain, whitewater rafting, rock climbing, our solo — expanded that comfort zone a little, like a sapling growing into a strong tree. (And then someone came and chopped it down. I’m not sure what that does to the metaphor.)

Expanding your comfort zone makes you more confident because you know more about the world, the space you occupy in it, and the things you can and can’t influence. You learn where your limits really are instead of guessing at them. It’s not just about big things like conquering your deep-seated fears and jumping off a platform when you are terrified of heights (she did it, by the way). It’s about removing doubt and dispelling mystery. Or, back to curiosity, it’s what comes after “I wonder …” when you can find the answer just by trying something new.

So I wondered what it would be like to fast, and I’m trying it. Let’s say I’m expanding my comfort zone while satisfying my curiosity. It may be cheesy, but that tree-ring lesson has stuck with me for over 20 years. I guess I’ll keep going with it.

(Outward Bound is awesome, by the way. I highly recommend sending your kids on a trip when they are old enough — or going on one yourself if your comfort zone needs some stretching.)

2:50 p.m.

I’m happy to report that my headache has not returned. I’m cruising on backup power!

8:45 p.m.

Kingsman was a terrible movie and I loved it. That is all.

10 p.m.

Tracy Reid posted this link on Facebook today. It’s an interview with a Buddhist monk, and towards the end he says this:

[F]asting highlights one’s attachments to food and to good flavor; thus it helps the practitioner to distinguish how much of his or her craving for food is need, and therefore normal and necessary, and how much is greed …

That’s definitely true for me. Over the last three days, I’ve been kind of amazed at how little food I actually need to feel good. Will I actually change my eating habits once my fast is done? Eh, probably not. Let’s be real. I like food too much, and I’m ordinarily much more active. I don’t think I could manage to run 3–7 miles every other day without going back to at least 2,000 calories per day.

But hey, it’s good to know at least.

11:30 p.m.


Fasting Journal, Day 4 of 4

1:15 a.m.

Can’t sleep. Also I am starving. I haven’t actually felt very hungry since Saturday morning, but right now I’m dying for something to eat. So I wimped out and opened the package of tuna fish I bought the other day. That’s another 150 calories.

Is it fasting if you keep cheating?

7:30 a.m.

I slept well but woke up with the beginnings of a headache, so I decided to break my fast. Three days on 650 calories is still a pretty solid accomplishment for my first fast, I think. That’s about 8% of what I normally eat, so I’ve been running on empty for over 90% of the time (I’m sure that’s not exactly how the biology works out, but I’m comfortable with that as an estimate).

8:15 a.m.

For breakfast, I had a hard-boiled egg, yogurt with granola and honey, toast with jam, and a cookie. Okay three cookies. I love cookies, and they were small and yummy.

It feels good to have food in my system again. While I was eating, I felt my systems “coming back online.” The last few days my senses have felt a bit muted, as if there was constant static in the background. Jess described me as mellow when we talked on Monday, but on my end it felt more like a slight buzz without the intoxication, like my senses were functioning at about 80% of normal. During breakfast, I felt a pretty noticeable return to alertness, like my body was waking up and turning all the knobs back up to full power.

So I think we’re done here.

(See the beginning of this post for my parting thoughts.)

  1. It’s still starving even if you have one little snack, dammit. 

Published by Sam Glover

Sam Glover is the founder of, and likes to skateboard.

Join the Conversation


  1. Thanks, Sam. Interesting comments, especially the focus on the way the body reacted to fasting and the way it affected mental states. Fasting is often associated with prayer, but I take it that wasn’t the case here. I would think the motivation for undertaking a fast would have some impact on the way you experience the fast. What do you think?

  2. This time I read the whole thing, which was very helpful. You provided thoughts on why you were doing this, so I didn’t have to guess. I’m impressed by your approach to this project and by the way you conducted ongoing evaluations. You stuck to it through a very long headache, and then you made a pragmatic decision to lighten up a bit; but you didn’t abandon the project entirely. I also very much like the way you drifted into a reflection on your experience with Outward Bound. Both experiences gave you a deeper knowledge of yourself and your tolerance for discomfort and pain. That’s part of the process of becoming a mature human being. You managed it well.

  3. The hardest part about fasting, for me, is just getting started. The first day is the hardest – it got easier for me as I went along. One of the biggest revelations for me was realizing how addicted to food I am. After the second day into a medically-required, four-day fast, I realized I wasn’t going to die – I kept telling myself: “I can do this”. Your feeling of a lack of energy is one that I totally agree with.

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