I stopped eating recently and tried water fasting. Not because I wasn’t hungry. Or because I was sick. Or because I ran out of groceries or lost a bet.
I stopped eating because I wanted to see what would happen.
My goal was to fast with nothing but water for 14 days. I made it to day 9, and not for the reason you’re thinking.
In that time, I lost 15.9 pounds (most of which I didn’t need to lose). My blood sugar levels plummeted to a terrifying 44mg/dl. My fingernails stopped growing. I didn’t poop for a week.
In summary, it was fun.
Maybe you’re here because you want to gawk at the stupid things other people do. Maybe you have heard about the myriad list of benefits associated with fasting and this article caught your eye.
Whatever the case, I’ll try to keep this interesting. Strap in. It’s going to get a bit crazy here.
I’m not a doctor or a licensed health professional. I’m just someone who has a passion for improving my own health and enough crazy to try just about anything once (or in this case 4 times and counting).
If you have any medical condition, are pregnant, plan on becoming pregnant, breast feeding, have a Xenomorph growing in your chest, under the age of 18, or suffering from the condition known as life, consult with someone first before you do anything stupid.
Are we cool? OK.
Water Fasting Rules
I’ve read that 14 days is a good upper limit for a healthy individual to fast without requiring monitoring from a healthcare professional. That 14 days should limit the amount of lean body mass (e.g. muscle) that I lose, and should let me fast safely without supplementing with vitamins and minerals.
Holy impossibility, Batman. That’s 2 weeks without eating. But I don’t do half measures. And I want to see what the limit feels like.
I stopped eating because I wanted to see what would happen.
The current world record for water fasting is 382 days set by Angus Barbieri. Granted, he started out at 456 pounds. But he slimmed down to a trim 180 pounds in 12 months without any food (Note – this was done under extreme medical supervision and key vitamin supplementation. Don’t try this at home.). So I’m pretty sure I can survive for 14 days with just water.
Some people go on “juice” fasts. Those seem ridiculous to me for a whole host of reasons I’m not going to get into right now. I’m doing a real fast thank you very much. No calories from anything. No “bit of cream in my coffee”. Nothing.
The current world record for water fasting is 382 days
I have the option to do tea, coffee, or lemon water as I’ve heard that experienced fasters use them to ease some of the symptoms of a water fast. Bah.
I’ve been meaning to cut out caffeine for a week to ensure I’m not addicted anyways. Let’s just make this as hard as possible.
I want a baseline for how hard fasting can be. That way I can figure out what can be done to make it easier the next time.
My goal is 112oz per day (7 pint glasses or 3.3liters). Nothing scientific here. It just seemed like a reasonable goal. I’m sure I would be fine with 100oz or 128oz as well.
Your kidneys can only process around 16oz (0.5L) of water easily per hour. Drinking too much too quickly can cause an extremely dangerous condition called hyponatremia. It can kill you. Don’t do that. Pace your water intake.
Exercise Every Day
Just to be clear, I do this every day anyways (811 days straight and counting). I’m not giving myself a pass while fasting.
I’m going to stick to my regular workout routine as well. Lots of heavy barbell work and running. No lightening the weights. I’m even going to add weights according to my workout calendar. I’ll list my workouts for each day in my daily review.
I want to ensure I don’t lose any muscle while water fasting. And maybe to feel like a bit of a badass at the gym.
I’m going to attempt to do everything I would as usual, except not eat meals.
This includes working, traveling, meeting up with friends. Everything. I’m not locking myself in a room for two weeks. I’m going to get stuff done.
I’m also recording my daily steps and its translation into miles to show a rough approximation as to how much I’ve been moving throughout the day.
My Water Fasting Experiment
This is my daily log for each day of the fast. I record a ton of data each day even when I’m not fasting.
Day 0 (Friday)
Weight: 178.3lbs (80.9kg)
Height: 6 feet 0 inches (1.83m)
Daily steps: 8,237 (3.9mi / 6.3km)
Workout: 5×5 Barbell Squat, Overhead Press, and Deadlift. Big weight workout.
I’m stopping all eating at 6pm today after dinner. My last meal consists of lamb tacos, pork tamales, and a side of potatoes. I savor it a little longer knowing that it will be the last nourishment my body will receive for a while.
Nothing but tap water for the rest of the fast. Having the first 12 hours of the fast be while I’m sleeping should help.
Feeling strong! Let’s get started!
Day 1 (Saturday)
Weight: 176.2lbs (79.92kg)
24-hour weight loss: 2.1lbs (0.95kg)
Total weight loss: 2.1lbs (0.95kg)
Daily steps: 13,240 (6.95mi / 11.18km)
Workout: 3.5mile run
Off to the races! This is my first attempt at a pure water fast. No coffee. No broth. Just tap water. I’m not sure what to expect. The first morning goes well.
In the afternoon, I get my first headache. Fortunately, I’ve done my research and go on a 30-minute walk to distract myself. Headaches, like hunger, are supposed to come and go in waves.
By the time I get back the headache is gone. I’m not even sure when it stopped on my walk. Problem solved. Thank you, Internet!
I’m drinking a ton of water. Probably more than necessary. Insulin tells your kidneys to hang on to sodium and water, and I’ve read that having less insulin in your bloodstream when fasting leads to extremely rapid water loss. My guesstimate is 7 tall glasses of water should help make up for what I’m losing.
I’ve put away everything that reminds me of food or eating. Hellooo clear countertops!
For my run, I’m wearing a heart rate monitor and keeping my heart rate to 144bpm max. My pace is almost 2min/mile slower than usual at the same heart rate. I’m chalking this up to lack of sodium and the extra stress my body is under from starting a fast.
My heart rate spikes into the 160bpm range almost immediately at a fast walk, but settles back down again after a few minutes into the 140s and I can pick up the pace.
In short, the run sucked. It wasn’t hard, but I was slow.
It’s around 6pm and I am beginning to miss food at the 24 hour mark. It’s not physical as much as psychological. I’ve never went a full 24 hours without eating before in my life. My stomach feels empty but not unpleasantly so. But my mind is telling me it is time to eat. Good thing it is easily distracted.
I was worried that hunger would make it feel difficult to get to sleep. Not a problem. I fell asleep almost immediately. No dreams of food either.
Day 2 (Sunday)
Weight: 172.4lbs (78.20kg)
24-hour weight loss: 3.8lbs (1.72kg)
Total weight loss: 5.9lbs (2.68kg)
Daily steps: 7,551 (3.56mi / 5.73km)
Workout: 3 mile walk (recovery day)
I’m down 6 pounds in 2 days. Wow. There is no way that is purely fat loss. I was hoping my high water intake would help mitigate the dehydration effects of water fasting. That doesn’t appear to be working.
I’m also pissing like a racehorse. I had one of those dreams last night where you are endlessly searching for but never find a bathroom. I awoke twice overnight for urgent bathroom trips. Average for me is close to 0 when I’m eating normally. I could have just chalked this up to my high water intake, but given the reading from the scale, I’m clearly dumping water.
Note – 6lbs is equal to a gallon milk jug filled about ¾ of the way with urine. Not that I’m saving mine. Because that would be weird.
Another big headache arose this afternoon. Hard, but I can still get work done. Another walk helped. Good thing I’m working from home, or I’d be a little unpleasant to be around.
I had one of those dreams last night where you are endlessly searching for but never find a bathroom.
I’m a person that used to go hypoglycemic constantly. I know what it feels like. Three to four hours after my last meal and I’d be a wreck. Jess would stash snacks in her purse to keep me fed and functional between meals.
I’m not hangry. I don’t feel any of the usual side effects of hypoglycemia. No shaking hands. No brain fog. No upset stomach. Just pissed off because my head hurts.
I’ve read that headaches are often a side effect of rapid water loss. Maybe I should have reconsidered my stance on no salt for this fast. Salt would have helped slow the rapid water loss, and theoretically the pain in my head. But I’m not changing the rules now. Onwards, for science!
Jess is eating something for dinner on the couch next to me. I’m convinced it is the most delicious meal to grace our home. Xena agrees and drools a little into her bed.
I’ve discovered a Jedi mind trick to block the thoughts of food, and it’s surprisingly effective. Just don’t look directly at the food. I can deal with the smell if I don’t combine it with a direct visual. I’m amazed that 90% of the battle so far is psychological and not physical. I would have thought it would have been about 50-50.
Sunday is my exercise recovery day. I usually walk by the lake for an hour or two. Easy!
Day 3 (Monday)
Weight: 170.0lbs (77.11kg)
24-hour weight loss: 2.4lbs (1.09kg)
Total weight loss: 8.3lbs (3.76kg)
Daily steps: 12,235 (5.77mi / 9.29km)
Workout: 5×5 barbell squat, bench press, and bent over barbell rows
Woke up easily at 4:15am. Not eating is making the process of getting out of bed easier at least.
Mondays, Wednesdays, and Fridays are big weight days for me at the gym. I like showing up at 4:30am so I don’t have to wait in line for a squat rack. Did my normal routine with an increase in weight from the previous week. Probably not a great idea as my body is in a catabolic (breaking down and repairing) state.
I’m still trying to maintain normalcy, so cheating on my workout isn’t allowed. I’m not expecting to gain any muscle mass in this experiment.
I found myself without a car this morning. I’m feeling energized and I decide to walk home from the gym instead of taking the bus. It’s only 2 miles.
By the time I get home I’m feeling strange. Like I’ve just ingested happy pills and am sliding down rainbows. I’m extremely euphoric. I sit down on the couch and smile at the ceiling for a while. This continues for around 45 minutes or so.
My theory is that the combination of heavy weights and cardio (from walking) raised my blood ketone levels extremely rapidly.
For those of you that aren’t familiar with ketones, they get produced by your liver as a fuel source for your body (and brain in particular) through the metabolism of body fat. Ketones are what keep you going when you are starving. A survival mechanism to supercharge you to catch the antelope for sure this time.
By the time I get home I’m feeling strange. Like I’ve just ingested happy pills and am sliding down rainbows.
Ketones are basically rocket fuel for your brain. I’ve ingested ketone salts directly before (usually before or during 20+ mile runs) and gotten a much milder euphoric effect. This was unlike anything I’ve ever experienced.
If you are eating normally, your blood ketone levels are almost certainly 0. It’s unfortunate that in our addiction to constant eating, we are missing out on this supernormal experience. It’s quite enjoyable.
So apparently fasting can get you high.
Day 4 (Tuesday)
Weight: 169.0lbs (76.66kg)
24-hour weight loss: 1.0lbs (0.45kg)
Total weight loss: 9.3lbs (4.22kg)
Daily steps: 7,981 (4.4mi / 7.08km)
Workout: 3mi run offroad run
Got up shortly after 4am and ran for a few miles in the dark. I like to run off-trail in the park by the lake, leaping over big rocks and running up and down the sand dunes. A combination of meditation, excitement, and a dash of fear.
It’s unfortunate that in our addiction to constant eating, we are missing out on this supernormal experience.
Running felt easier than on day 1, but I’m still noticing a significant performance decrease from my baseline pace.
I feel fine. More than fine. Energized. Awake. A touch hungry, but not as much as the previous days.
From everything I’ve studied about fasting, day 2 and 3 are the hardest and it usually becomes easier after that. So far that seems to be true. The headaches are gone. My body doesn’t appear to be dumping water anymore. I’m only down 1 pound from yesterday, which is in the range I’d expect during a water fast.
A pound (0.45kg) of fat is equivalent to roughly 3,500 calories. Roughly 6 Big Macs.
My resting metabolic rate (RMR), the number of calories my body consumes if I were to lay in bed all day, is roughly 1,800 calories. But since I’m active (I’m on my feet all day), my actual energy requirement is around 3,000 calories to maintain my weight of 175lbs.
When I was doing my research about fasting, one fact that I kept finding in the literature was surprising. Not only does your metabolism not slow down during a fast, it speeds up. Not considerably, but studies measure it having up to a 10% boost. If I’m getting the full 10%, that’s 3,300 calories per day of energy I’m burning.
Doing some simple math, if I’m completely abstaining from food and staying reasonably active, I’d expect to lose on average between 0.75 and 1.0 pounds of fat per day. That’s exactly what I’m seeing on the scale now that I’ve (hopefully) stopped dropping water weight.
Who says math isn’t useful?
Day 5 (Wednesday)
24-hour weight loss: 2.0lbs (0.91kg)
Total weight loss: 11.3lbs (5.13kg)
Daily steps: 8,883 (4.21mi)
Workout: 5×5 barbell squat, overhead press, deadlift
Another big leg day for my workout. I increased all my weights by 5 lbs from day 3. But I’m feeling my heart pounding more than usual after every set. Jess has a blood pressure cuff, but I’m not quite crazy enough to cart it with me to the gym. I’m wondering if my blood pressure is higher than normal, or if this is just another symptom of low sodium intake.
I’m also feeling better than I have in months. I’m not euphoric like I was on day 3. Just an overall feeling of wellness. Like a dimmed light bulb that has the brightness turned up a notch or three.
I overheard some people on the street discussing how hungry they were around lunchtime. I just smile knowing that I haven’t eaten in 5 days, won’t eat anything for another week, and I’m not feeling anything at all. I revel in my newfound superpower in silence.
My energy levels are high throughout the day into the evening. Normally I’ll start to wind down once it starts getting dark outside. But my mind is clear and I’m full of energy. Hopefully this continues.
Day 6 (Thursday)
Weight: 165.4lbs (75.02kg)
24-hour weight loss: 1.6lbs (0.73kg)
Total weight loss: 12.9lbs (5.85kg)
Daily steps: 11,377 (6.0mi / 9.66km)
Workout: 3mi run
I slept great last night. I track my sleep every night with the SleepCycle app on my phone. It’s not a perfect measurement of sleep quality. But it is the best I can do without strapping electrodes to my head.
I just smile knowing that I haven’t eaten in 5 days, won’t eat anything for another week, and I’m not feeling anything at all.
I normally don’t achieve a sleep quality score above 80% (my lifetime average is 63%). Throughout this entire experiment I’ve been hitting 80% and above every night. One night I even hit 93%. It appears I sleep better when I’m not eating. Not something I would have predicted.
This is a bit gross. I haven’t had a bowel movement in nearly a week. I guess that makes sense since I’m not eating anything. I’m not constipated. My body just doesn’t need to go.
I’m not even having thoughts of food anymore. I’ve gotten proficient at blocking the idea of eating from my mind. The only physical reminder I have is a slight empty feeling in my stomach that is easy to ignore.
Today I started getting thirsty every hour like clockwork. I’m not sure if this is me becoming habituated to my 7 pint glasses of water a day, or if I’m dumping more sodium. I’ll find out tomorrow on the scale.
My wedding ring is nearly falling off my finger. It wasn’t tight to begin with, but losing nearly 13lbs in 6 days is making its grip on my finger precarious. If I were to swim in the lake it would almost certainly fly off.
I am slightly cold an hour before bed. But it’s also getting colder outside and I keep the temperature at a budget conscious 68 degrees. Maybe my fiery metabolism is finally taking a hit. Let’s see if this is a trend.
Day 7 (Friday)
Weight: 164.8lbs (74.75kg)
24-hour weight loss: 0.6lbs (0.27kg)
Total weight loss: 13.5lbs (6.12kg)
Daily steps: 7,490 (3.54mi / 5.70km)
Workout: 5×5 barbell squat, bench press, bent over row
I jumped out of bed again at 4:15am. I’ve been trying to hack my body to be an early riser for nearly 2 years. It’s never been this easy.
Another big weight day at the gym. Added 5 pounds to each of my lifts again. I learned why you shouldn’t keep increasing the load while you are fasting. I’m struggling to finish the final sets. I don’t miss a rep, but this is much harder than usual. I feel a bit dizzy at the end of my 5th set of squats.
Lesson: don’t add weight when fasting. Per all the research into fasting and athletic performance, I’m likely not losing muscle. But I’m almost certainly not adding any either. I should have been keeping my weights constant, or even lightening them slightly.
I feel fantastic all day through the evening again. I’m getting even more cocky about my starvation superpower. The guy who did water fasting for 6 days in that GQ article was a whiner. This isn’t hard at all. And I don’t need to be locked in a clinic for 24 hours a day to do it either.
Day 8 (Saturday)
Weight: 162.4lbs (73.66kg)
24-hour weight loss: 2.4lbs (1.09kg)
Total weight loss: 15.9lbs (7.21kg)
Daily steps: 10,039 (5.47mi / 8.80)
Workout: 4mi off-road run
More great sleep and jumping out of bed ready to go at 4:15am. I do a trail run in the dark that was incredibly refreshing, but I’m still running slow. I’m slightly faster than earlier in the week, but it feels more difficult in terms of effort.
The guy who did water fasting for 6 days in that GQ article was a whiner.
A few other things I’ve noticed:
- My fingernails haven’t grown in 7 days. I trimmed them exactly a week ago. They are still roughly the same length.
- My beard appears to be growing slower than usual. I shave once a week, and it seems shorter than usual. Maybe 30-40%?
- I forced a bowel movement today to verify I’m still a functional human being and not incredibly constipated. Yup. Not immortal yet as I can still poop.
- Glucose: 44mg/dl (normal is 70-100mg/dl. I’m usually on the high end of the range)
- Ketones: 5.4mmol/dl (normal is 0.0)
Wow. That’s low.
One of my biggest mistakes in this experiment was not measuring my blood glucose and ketone levels every morning. I’ve got all the equipment. I’m normally a data fiend. I just completely forgot to take measurements until day 8. I wasn’t originally planning on writing about my experiment.
For those of you who aren’t diabetic, your fasting blood glucose is a measurement of how much sugar you have floating around in your blood at a given time. Since this is the primary fuel source for every cell in your body, maintaining it within a tight range is a top priority.
Once you get below 70mg/dl you reach hypoglycemia. Normally this comes with symptoms like:
- Blurry vision
- Rapid heartbeat
- Pale skin
- Trouble thinking clearly
- Loss of consciousness, seizure, or coma
Not a great list of symptoms. My blood sugar is at 44. If I was in a hospital they’d probably have rushed me to the ER and hooked an IV of sugar into my arm. But I’m feeling good enough to go out and run around in the dark to vault over rocks and logs before 5am.
The reason I’m not in a coma right now is from the magic of the ketones coursing through my bloodstream. They’re also likely the reason I’m feeling so alive and energized. Ketones are rocket fuel for your mind and body. It’s too bad you need to starve (or simulate starvation by restricting carbohydrates) to get your body to generate them in sufficient quantities.
If I was in a hospital they’d probably have rushed me to the ER and hooked an IV of sugar into my arm.
I’m a Quitter
I’m making the call to end my water fasting early today.
I’m not hungry. I’m not feeling sick. I feel more alive and energized than I have in a long time.
But there are two factors that are making me want to stop.
Factor 1 – I’m turning into Skeletor
What I look like now.
I didn’t have much fat to lose in the first place. I’m normally around 10-11% body fat at my fighting weight. I’ve just lost 16 pounds in the past 8 days. My ribs are poking through my skin. I’m starting to look emaciated.
My experiment in water fasting was to see how it feels and how it impacts my body. Not lose weight. One of my goals for this year is to put on another 10 lbs of lean body mass. I’m confident that I could keep going to day 14 without much effort. But I’m concerned pushing forward is going to set me back for weeks, if not months.
Factor 2 – FoBAB
My ribs are poking through my skin. I’m starting to look emaciated.
Note: J. Wilson has done a 46-day beer-only fast. This is a thing? I’m pretty sure this shouldn’t be a thing.
So, with the twin specters of emaciation and beer FOMO, I decide with some trepidation to call it at day 9.
Breaking the Fast
Day 9 (Sunday)
Weight: 164.9lbs (74.80kg)
24-hour weight gain: 2.5lbs (1.13kg)
Daily steps: 7,768 (3.66mi / 5.89km)
Workout: 3mi walk (recovery day)
No regrets. I made the right decision to end my fast early.
But what about refeeding syndrome?
Refeeding syndrome occurs when you reintroduce food too quickly after an extended period without.
It’s a serious medical condition. One that can be lethal. But it applies to people who are actually starving. I wasn’t starving.
People choose to end their extended fasts in many different ways. Most people do it gradually over a period of days. And most of the articles about it online make it seem like it is something that requires a degree in nutritional science to understand.
I believe that feasting and fasting are natural cycles of what it (used) to mean to be human. We’d starve for a while. Then we’d discover something delicious and stuff our faces until our loincloths would pop off.
To honor my distant ancestors, I break my fast in the most epic way possible.
I taste some of the best barrel aged beers that can be obtained in Chicago. I eat a pound of cheese curds, beef nachos, and guacamole and wash it down with more barrel aged nectar. I consume at least 2,000 calories in one sitting. I don’t experience any digestive problems other than simply feeling full. It is a glorious.
Refeeding syndrome clearly isn’t an issue.
I eat a pound of cheese curds, beef nachos, and guacamole and wash it down with more barrel aged nectar.
- Starting your fast after dinner is the easiest way to begin
- Days 2 and 3 are the hardest
- Fasting becomes progressively easier after Day 3
- Water loss is extreme for the first 48-72 hours
- You can fast on a work week
- Fasting may make you euphoric for short periods of time
- You can continue to exercise while fasting. Just don’t expect too much.
- Fasting increases energy levels and focus beyond normal levels
- Fasting increases the quality and restfulness of sleep
- Refeeding syndrome probably isn’t something to worry about
- You can break a fast in the most epic way possible
- Fasting leads to extremely rapid weight loss
- Weight regain post-fast is minimal
But of all the things I’ve learned, what has resonated with me the most is how optional food really is.
You need food to survive and grow. But you don’t need to have it every day. If you are a healthy you can even go a week or two without eating and still be fine. Maybe even better than fine. Dare I say superhuman?
3 things I’ll change for future fasts
1. Add Salt
I add salt to my water on fasting days. Usually totaling between 1 and 2 teaspoons total over the course of a day. This seems to limit the rapid water loss in the first 48 hours, and helps reduce the duration and severity of any headaches.
2. Allow coffee/tea
Restricting coffee for my first fast was mostly unnecessary. I get nearly the same effects when I fast with black coffee and tea as I do with just water. Adding coffee and tea makes the fast much more enjoyable as well.
Just keep it within reason. I don’t ever fast with more than a cup or two of coffee per day.
3. Limit the length
I’ve tried a few different durations of fasts. Depending on what your goals are, I’ve found that tweaking the length can be beneficial.
My favorite is the 24 hour fast. I stop eating at dinner and don’t eat until the following dinner. It’s effortless and I get most of the hormonal benefits from fasting without any real effort. I usually do these twice a week on non-weightlifting days.
My goal is to continue a 7+ day water fast at least once a year going forward. I’m not going to get into the science of why in this article, but I personally believe it shows a lot of promise in keeping my body healthy for as long as possible.
I do not recommend doing extended (5 day+) fasts back to back. Everyone is different and needs time to recover. I would recommend at least a month before doing another extended fast.
You’ve stuck with me this far on a 5,000 word article about how I willingly stopped eating for over a week. You clearly have an interest in the subject of fasting.
If you’ve never had the experience of going more than one skipped meal without food, maybe now is the time. Going without eating is an essential part of what it used to mean to be human.
Give your self a small challenge. Do a 24 hour fast. Stop eating after dinner. Don’t eat again until dinner the following day. You’ll survive. You may even enjoy it.
Have any experiences with fasting? Share them in the comments below.