I didn't eat food for 5 days, here's what happened

Notes, questions, answers and diary entries from my first five day fast (120-hours consuming water only).

I didn't eat food for 5 days, here's what happened

Last year I did 4 days, this year it's 5 days. Who knows, maybe in 25 years I'll be going a month at a time (probably not).

Thinking about trying your own extended fast? Well, you're about to dive into the article/diary/question and answer style documentation of my first 5 day fast.

I've started by answering some of the questions I would've liked to have known before starting a 5 day fast and then finished with a day by day journal entry and some extra resources you might want to check out to learn more.

Disclaimer: What you're about to read is not medical advice, only anecdotal stories from my experience during my first five day fast, I am not a doctor. If you're unsure about anything, seek professional medical advice.

Video documentary

Want to watch it happen?

There's a video diary/mini documentary to go along with this post. It captures a few of the emotions and day to day activities Sam (my little brother) and I got up to throughout the five days.

Rapid fire questions

Why did you do a five day fast?

Aside from the plethora of health benefits, the main reason was to see what it was like to go five days without food.

If you had told me 3-years-ago, I'd have gone five days without food an operated almost as normal, I'd have told you to f*ck off.

How did you start the five day fast?

Since I decided to fast from Monday to Friday, my last meal was Sunday night. I kept it low carbohydrate (chicken and greens).

The idea here is to lower the amount of excess glycogen your body stores so you can enter ketosis faster, usually one of the hardest parts of an extended fast is switching from using glycogen as a primary fuel source to using ketones.

On Monday morning I went for a long walk (90+ minutes but could've been longer) to continue to burn off excess glycogen.

High intensity exercise on the first morning would also be a good idea.

How much weight did you lose during the fast?

My average weight across the five days were as follows:

  • Day 1: 74.85kg (165.0lbs)
  • Day 2: 73.30kg (161.6lbs)
  • Day 3: 72.90kg (160.7lbs)
  • Day 4: 72.60kg (160.0lbs)
  • Day 5: 71.80kg (158.3lbs)
  • Day 6 (1 day post fast): 71.42kg (157.4lbs)
  • Day 12 (1 week post fast): 71.78kg (158.2lbs)

I've put averages because I'd usually weigh in the lightest upon first waking up and going to the toilet. Then throughout the day as I drank water, my weight would go up.

What did you consume during the fast?

Water, water with sprinkles of sea salt (2-3 sprinkles at a time, I never measured it), sparkling water, ice and standard magnesium tablets (2 per night on days 2, 3, 4).

Did you exercise during the fast?

Yes. Every morning started with a slow, below stressful walk.

On night 1, I played touch football for 40-minutes. And then on days 2, 4 and 5, I lifted weights and went to Brazilian Jiu Jitsu training.

For weight lifting, I stuck with compound movements such as deadlifts, pull-ups, bench press and walking lunges. The volume and weights were about 70-80% of what I'd usually do, 20-25 minutes maximum.

Getting started was a little slow but once the blood was flowing, I felt incredible.

During the fast, I always felt the best after exercising.

What was the hardest part about the fast?

I started the five days with a friend and my little brother, and halfway through day 3 my friend stopped and then on the night of day 3, my little brother stopped.

Of course, stopping is perfectly fine, you can stop at any time. But I knew I wasn't going to.

I think the fact I knew I'd only just crossed halfway and the two people I'd started with stopped played around with my head. So I took a nap and continued.

Missing out on meal time rituals is also a hard part. Eating food with family and having a meal after a workout or as a reward for finishing a task is among my three favourite things in the world to do. Sitting down with the family whilst they eat dinner and you sip water is also an interesting experience.

How did you spend time during the fast?

A lot of time is spent doing nothing. You'd be surprised how much time you spend eating. Between shopping for food, meal preparation, sitting down to eat and cleaning up. When you're fasting, none of this happens. So I found myself with plenty of time on my hands.

Post lunchtime naps became a thing. I'd usually spend the morning reading, writing, studying or coding (how I usually spend the morning), workout around lunch and then have an afternoon siesta, get up and do a little more reading or work and finish the day with an afternoon walk or another training session.

It was also cool to study the information offered by the Zero Fasting app whilst I was going through the fast. The app updates as you enter different stages and tells you about each one. Each day I found myself reading the blog posts and watching the videos on the app telling me about what was going on inside.

How were your concentration levels during the fast?

I tried to keep the five days as normal. Meaning, I'd do all the regular things I do: reading, coding, writing. I found little to no change in my cognitive abilities. If anything, I was able to concentrate more since I had more free time.

What did you break the fast with?

A black angus sirloin steak seasoned with salt.

I'd read on the Zero Fasting app, after an extended fast, you want to break it with a simple food, for example only one kind of food rather than multiple.

And if you feel fine after eating only one kind of food, you can start introducing more.

An hour after breaking the fast with steak, I felt great, so I ate some salad and almond butter.

I can confirm: hunger is the best seasoning (even though I wasn't hungry).

What was your sleep like?

On a previous fast my sleep was interrupted but this one was different. I noticed no major changes to my sleep. Maybe the magnesium tablets before bed helped out.

I did find myself waking up a little more dehydrated than usual, which meant getting out of a bed was a little harder.

What were your blood ketone measurements?

I only started measuring blood ketones at the end of day 2, which is about when ketosis starts to kick in.

My measurements ranged from a minimum of 0.2mmol/L on the night of day 2 to a maximum of 3.4mmol/L on the morning of day 4 to 2.1mmol/L just before breaking the fast.

Unlike last year, I didn't measure blood glucose levels.

What was going to the toilet like without eating anything?

Uneventful. Not much happened. I missed the toilet up until the morning of day 4 and day 5.

Did you ever get hungry?

Only on day 1 lunchtime and day 2 lunchtime, but even then, it felt like being hungry out of habit (I usually only eat lunch and dinner) rather than actually being hungry.

It's counterintuitive, but the further you go along, the less hungry you get. It turns out the hunger hormone Ghrelin (the signal which tells your body you're hungry) drops to levels close to that of after a meal after ~72-hours.

I felt the least hungry after training or exercise. Even at the end of day 5, after finishing a Jiu Jitsu session, I didn't feel hungry at all.

What was the best part about the fast?

Feeling in tune with nature. It's indescribable but I felt as if I had nowhere to be and nothing to do, completely at peace but also ready to hunt if I had to. My primal instincts began to kick in.

Would you do it again?

Yes. 24-hours at least 1-2 times per month and 3-5 days (maybe longer) at least once per year.

Journal entry

I took notes throughout and at the end of each day to describe how I was feeling. I've copied them unedited here.

Day 1 – Monday 28th September 2020

  • First ever 5 day fast. Started after dinner on Sunday. Woke up this morning feeling great. Went for a long walk with Sam. Sam & Dave & Chop are all doing it. It’s going to be cool to see how they feel along the way.
  • Took progress photos and weighed in this morning, 74.8kg, a good starting point for me as I decided not to go too much over 75kg again.
  • 1030pm. At the end of day 1 now and laying in bed feeling great. Had a nap during the day but I think that was mostly to get rid of the extra caffeine. I think I’ll do an extended fast at least once per year.
  • The other boys said they feeling it. Their bodies must not be as adapted as mine is to being without food for a longer period of time. Sam & Dave were really hungry. Dave even called me and said he was thinking of quitting. I’m glad he didn’t. If he pulls through he’s going to be a changed man. I will be too.
  • I’m in more for the mental game than the physical game. Just to know I can go 5 days without food if I needed to. I’ve done it before. Practicing for the worst case scenario.
  • Time for bed. I’m feeling excellent. A little tired but that’s normal. I wonder how tonight’s sleep will go. Going to try and keep tomorrow as a normal day and do the things I normally would.

Day 2 – Tuesday 29th September 2020

  • Woke up a little later. Felt more tired then usual. Worked out after going to the bathroom it was from being dehydrated. Had a few sprinkles of salt in water and started feeling better.
  • Went for a walk with Sam and the dogs along the front. Sam told me he usually wakes up hungry but not so much today. Then we went back to the Nest and he weighed in 1.9kg less (102.1kg to 100.2kg) and I weighed in 1.8kg less as well, 74.9kg to 73.1kg.
  • Worked on a newsletter (you don’t need permission) and got it published today with no dramas. No real lack of concentration. Could keep working without interruption.
  • Feels like my haemorrhoid is shrinking (the one from getting choked the fuck out at my last BJJ comp). Hasn’t been as much of a burden today. Maybe because I haven’t taken a shit yet and whipping my ass hasn’t aggravated it.
  • Haven’t taken a shit yet. Maybe my body is absorbing all of the nutrients it had and is waiting until absolutely necessary before going to the toilet.
  • Picked up Ketone and blood glucose meter from home and going to test my levels after BJJ.
  • Sam and I went to gym and had a slow start but eventually when the blood got moving we ended up with a great whole body session: incline bench press, deadlifts, lat pull downs/pull-ups and shoulder press.
  • Never really felt hungry today except for around lunchtime (when we went to the gym) but I feel this was again out of habit rather than out of a need for food.
  • Had a nap this afternoon which went on longer than I thought. Felt a little drained and it was as if my body was recharging itself. After getting up I felt incredible. No hunger just a constant flow of energy.
  • These kind of naps might be caffeine exiting my body. I find I have these kind of naps within a couple of days of giving up caffeine. Almost like my body is rediscovering its natural energy levels.
  • Overall feeling: great, except missing the ritual of food, it makes itself known around meal times. All other times it’s fine.
  • Going to wake up and be over halfway. That’s exciting. All downhill from there.

Day 3 – Wednesday 30 September

  • Woke up and stayed in bed for a little while. Felt tired but later realised that was because of dehydration. Woke up and had some salt in water then felt great.
  • Went for a walk with Dad, Dave, Telarni, Wylder, Savannah and the dogs in the morning. Was hot so felt a little lacklustre after that. We talked about Tangalooma while walking and all of the epic feeds we’re going to have over there. Not a good idea to talk about feasting whilst you’re in the middle of a fast.
  • Did some writing when we got home then laid down for a nap. Again feeling a little drained but nothing over the top. Was more cold than any other day today. Had to get a hoodie and a blanket to have a sleep. After waking up had a long hot shower and felt better.
  • Finished the writing project I started in the morning in the afternoon. Had a great level of concentration. Knew I needed to get it done before the end of today. 1000+ words on the best machine learning resources I’ve found in the past month.
  • Dave broke his fast around midday today. Sent through a video. It broke my heart. He sent through that he was feeling great this morning. Must’ve been the walk that changed it.
  • Sam broke his fast around 5:30pm at The Full Moon Hotel with a steak. He said he’d been feeling stressed all day thinking about food. That’s not how you want to feel. After eating he felt great and came home and cooked dinner for the family.
  • When we bought supplies for dinner, I walked through the supermarket with Sam and felt in a complete state of zen. I didn’t need food and my energy levels were perfect. It was as if I was a monk. I enjoyed that feeling.
  • Sitting at home with the family for dinner, food was tempting but I looked on and enjoyed their company. I’ve said to myself I’m going the full 5 days, so I’m going to go the full 5 days.
  • Measured my blood ketones this evening and came in at 3.3mmol/L, deep into ketosis.
  • Overall feeling: Great. I’m in chill mode. energy levels aren’t blasting through the roof but they aren’t extremely low either. I don’t feel hungry but I do feel the longing for the feeling of sitting down for a meal with others. That’ll come on Friday.
  • Time to sleep through the next 8-9 hours or so of this fast and wake up being a step closer. I’m not trying to hurry it up, best to enjoy the process to laugh about it later.

Day 4 – 1 October 2020

  • Woke up this morning and did the first shit of this entire journey. It wasn’t much. Not solid, not liquid but something.
  • Weighed in at 71.9kg before drinking some salt in water.
  • Seems to be a common theme: waking up dehydrated.
  • Went for a walk with Sam and Slick, turned around earlier than usual because it was getting hot.
  • Went to coffee with Josh, Sam and Slick, I sipped lemongrass tea and soda water whilst they had coffees. Felt fine. Zero hunger.
  • Speaking of zero hunger, I’ve had zero hunger all day. Very counterintuitive.
  • Blood ketones were at 3.3mmol/L this morning and 0.9mmol/L this evening after training.
  • Went to gym with Sam during lunchtime and we got a great pump. He said he was feeling amazing after breaking his fast the day before and then having food in his system during the workout. Was so stoked to see him enjoying it as much as he was. Did some bench press, deadlift, shoulder press, pullups and finished with biceps and triceps. Felt incredible after. The pump is the cure.
  • Had a nap after going to gym. Then woke up with plenty of energy and did some reading before taking care of same email and replying to my students.
  • Trained BJJ in the evening. Had a few rolls and felt full of energy. Not sure anyone would’ve noticed I hadn’t eaten in 4 days. Hell, I didn’t even really notice.
  • Home later tonight yawning my skull off. I’m in uncharted territory now. This is officially the longest I’ve ever gone without food. I’m going to wake up with around 12-hours to go.
  • I feel like a kid going to sleep knowing it’s his birthday tomorrow.
  • Overall feeling: Excited and proud of the past few days. It’s been a great bonding experience with Sam as well. I’m so thankful for his help. I’m getting the feeling of being in tune with everything again. A calmness I haven’t experienced many times before. Perhaps that’s not the case externally, Sam said I’ve been angry the past few days. That’s not how I feel internally though. All I know is, I’m lucky to have such a great little brother and friend.

Day 5 – 2 October 2020

  • Woke up feeling the best I’ve felt in the last few days. Plenty of energy. Zero hunger. Minor dehydration. A few sprinkles of salt and water fixed it.
  • Took a shit for the second time in 5 days. It was close to liquid. Might have been the magnesium tablets I had last night (2 x high strength magnesium, I’m not sure what else they’ve got in them), I read somewhere too much magnesium can give you diarrhoea.
  • Walked along the waterfront with Slick and the puppies. No one’s out because everyone is away on school holidays. Enjoyed the quiet and reflected on the deep sense of calm I’ve been feeling. It’s hard to put into words. But for the past 20-hours or so, I’ve felt more in the now than I can remember feeling.
  • Spending the day as usual: studying, writing, moving.
  • Going to collect dinner for tonight, the crew are coming round for steak night. I’m excited but I don’t need to eat (I know I eventually do). If I kept feeling like this, I could keep going.
  • Had a nap during lunchtime. That seems to be the tradition now.
  • Wrote some code and replied to emails in the afternoon.
  • Went to gym with Sam at 4:30pm and did a simple weightlifting session: dumbbell rows, bench press, overhead press, weighted lunges.
  • Came home from gym and prepared dinner.
  • Went to BJJ and had a great session, rolled with Jaz and Billy. Was questioned by Jaz how I had so much energy. Brooke (Jaz’s friend) asked what was hard, I told her the same thing I told the guy who asked me on Twitter: I missed the ritual of eating food with family and friends, that’s one of my favourite things in the world to do.
  • Cooked dinner after BJJ, steaks, broccolini, broccoli, cauliflower, cheese, Dave and Telarni bought over a Greek Salad.
  • Ended the fast on the Zero app and took a bite of steak. It melted in my mouth. Wasn’t hungry at all but after I took a bike the switch flipped and I remembered how good it is to eat food.
  • What an experience. Feeling jacked after having a meal. Weighed in at 11:00pm the lightest I’ve been in a while: 71.7kg, lean and shredded.
  • This will be a regular thing every year.

Progress photos

progress photos from day 1 to day 5
Progress shots from the mornings of days 1 to 5 of the fast. We kept the tripod in the same place of the room each day and I tried to stand in the same place for the same lighting. However, due to the weather, some of the lighting is different for each photo. The main thing I notice from day 1 to day 5 is the tightening up of the abdominals (less water).

Every morning of the fast, including the morning after breaking the fast, we took progress shots. My goal wasn't weight loss or any kind of major body changes but it was cool to see everything tighten up.

comparison photo of day 1 and day 6 of the fast
Left: shot on the first morning of the fast (74.8kg). Right: shot on the morning after breaking the fast (71.4kg). Towards the end of the fast, I noticed the veins coming out on my lower abdominals.

Resources to learn more

If you want to learn more about fasting, its benefits and what happens during extended periods without food, I'd recommend the following resources.

  • All of Jason Fung's articles Jason is a Nephrologist who specializes in type 2 diabetes reversal and intermittent fasting. His works discussing the physiology of fasting are world class.
  • Zero Fasting app/website – Alongside using the app's main feature: a countdown timer. I found myself reading and watching Zero's educational articles and videos on fasting almost every day. It was cool to learn about what was (supposedly) happening to my body as I was experiencing it.
  • 4-day fasting article and video – Last year I did my first extended fast (4 days), aside from being longer, the main difference between that one and this one was the lack of caffeine consumption. During the four day fast, I had black coffee in the morning, during the 5 day fast, I didn't have any caffeine. You can read the article version or watch the documentary.

If you have any questions or would like to know more, feel free to ask.