The 2-Day Fast

[Last updated 27th August 2019]

2-day fast

Recently there has sprung up a fad called the 5:2 Diet. The two-day fast is not to be confused with that.

About a month ago I was asked by a few people about this 5:2 Diet, and it sounded a lot like my own special fasting strategy.

But it wasn’t.

The 5:2 Diet is some adapted version made for weaklings, where you are “allowed” to eat 500-600 calories a day for two days of the week, and then eat completely normally for the other five days.

So, the 5:2 diet is not fasting. It’s just calorie restriction, and it’s vastly inferior to my 2-day fasting strategy for the following reasons:

  • The 2-Day Fast gives you a natural high.
  • The 2-Day Fast is a great exercise for Breaking out of Homeostasis.
  • The 2-Day Fast gets you ripped pretty damn fast.

The 2-Day Fast is a 40-48 hour period where you don’t consume more than circa 50 calories at a time, to avoid activating your digestive system.

For Beginners: Fasting 101

Note: If you’re new to fasting, here are three summary posts I’ve written about two of the most famous books about intermittent Fasting.

  • Part 1. Eat Stop Eat – 24 hour fast once or twice a week.
  • Part 2. Fast-5 diet – ca 5 hours to eat every day and 19 hours fast.
  • Part 3. My take on IF, bulletproof coffee and miscellaneous stuff.

I haven’t written a book on fasting, but I’ve done it for years.

Here’s my method…

Most people think that certain things in life are “set in stone”; they think hormonal levels are one of these things that cannot be changed.

I have good news for you: Those people are wrong.

You CAN change your eating patterns and how your body responds to hunger.

I speak from experience. I am never hungry (except after workouts).

This is great because:

  1. It saves me lots of time and money,
  2. It helps me stay lean,
  3. It makes me more productive and,
  4. It gives me much control over my behavior. . .

. . . (since I don’t have to think about food).

Is this hard?


It’s almost effortless because I’ve trained my body to go for long random stretches without food, and my hormonal levels have adapted.

How Eating Dulls the Mind

In your body there’s something called the autonomic nervous system (ANS) and the parasympathetic nervous system (PN).

The ANS has to do with being active and doing stuff, the PN has to do with resting and conserving energy.

Your body can only activate one of these systems at a time. 

Guess which system most people spend the majority of their time being in?

The PN.

When you eat you are activating the PN and it puts your body in a state of “rest-and-digest”, which makes you mentally lazy and demotivated.

–Just like a grazing cow.

"Because I eat all day I don't have to do any heavy thinking."

“I don’t have to do any heavy thinking, because I eat all day long, every day.”

The 2-Day Fast will snap you out of this daze in a major way!

You’ll be able to think MUCH more clearly.

The 2-Day Fast as a Way to Break out of Homeostasis

Fasting is a great way to practice your willpower because it involves an easily observable plateau, where you’ll experience an initial hunger phase.

This urge you’re feeling, which is telling you to eat, is triggered by your hormones–in order to keep you in homeostasis!

Homeostasis is the biological process by which your brain and body:

  1. Strive to minimize stress and maintain balance,
  2. Avoid change and save energy and,
  3. Flee from discomfort and pain.

When you go without eating for 16 hours or so, you’re breaking out of homeostasis, getting the body out of a rut.

If you aren’t used to it, don’t freak out. It’s a bit uncomfortable, but it’s only your homeostasis, wanting to return to its normal state.

–This is the #1 reason why most people fail with fasting.

Since they don’t know about homeostasis, when they try to change something in their lives–and it feels uncomfortable–they think it’s dangerous. . .

. . . and they stop and quit!

But it’s not dangerous, it’s just homeostasis playing tricks on the mind!

The discomfort is only temporary, in the transition.

Many people who have never fasted before react to this like they’re going to die from starvation, but the initial spike of hunger is completely harmless.

When you do it a few times you’ll know exactly what’s happening, and it becomes easy to mentally brace yourself against it.

Why Doing a 2-Day Fast is a Good Mental Practice

The 2-day fast is a great way to break out of homeostasis because you get feedback quickly. And it’s easy to see how your brain and body will try to fool you into quitting. It’s good practice because it’s so damn predictable.

This hunger-plateau is hard to overcome for most people because they trust their emotions too much–and now their emotions are telling them to eat quickly or something dangerous is going to happen.

You must brace yourself for this oncoming barrage of negative emotions and strange voices in your head telling you to stop what you’re doing.

These are the lies your brain and body tell you to keep you in homeostasis.

. . . And stop you from pushing your limits.

Your brain is wired for saving energy and remaining comfortable.

When you do a 2-Day Fast you break out of your usual rhythm–the homeostasis. The body resists it and puts up a little fight.

However, the resistance stops after a couple of hours, once you have broken through the hunger plateau, and your hormonal levels adapt.

I experience the hunger plateau around 16-20 hours. After 21 hours, like clockwork, it stops and I achieve a natural high.

The 2-Day Fast as a Way to Get Naturally High

When you don’t eat for a while your ghrelin levels (ghrelin is a hunger hormone) will increase, and this gives your brain surges of dopamine (the neurotransmitter of pleasure and focus), which makes you more curious while improving your ability to learn things.

–This makes reading and studying great activities while doing a 2-Day Fast.

I once sat and read a book about Napoleon for 24 hours straight, with the exception of bathroom breaks.

2-day fast

I don’t think I’ve ever been as immersed in a book as I was then.

Two things usually happen to me once I get through the hunger-plateau:

  • #1: Most notably, I experience an increase in cognitive and introspective abilities somewhere around the 20-hour mark after beginning the fast. This is accompanied by slight shivers as I slowly begin to get a bit colder. I also experience a tingling of energy in the back of my head.
  • #2: Following this, I start getting into an incredibly deep state of focus. I can feel my brain flex. My brain is now in an activated state for many hours to come.  This feels euphoric. It’s hard to describe it to someone who hasn’t experienced it. It’s like being curious about everything.

These sensations remain for a maximum of 48 hours (for me).

I’ve also done longer fasts (up to 80 hours), but I don’t particularly like it. I get weak and moody from doing it.

The 2-Day Fast is by far the most pleasant (and productive) fasting method, as it induces euphoria and increased focus.

The 2-Day Fast as a Way to Get Ripped

This one is a no-brainer.

If you don’t eat for 40-48 hours that’s a lot of time you spend in ketosis (fat-burning mode), effortlessly shredding unnecessary body fat.

I dropped from 77 kilos to 70 kilos in a 3 months by pulling 2-Day Fasts every Sunday through Tuesday. But then I stopped because it was too powerful, and I got scared–I didn’t want to lose more weight!

I still use do 2-Day Fasts occasionally, but not because I want to lose weight.

I might do it if I am busy and need to get things done. Or to practice breaking out of homeostasis to make sure my willpower stays strong.

How to Go on a 2-Day Fast:

Depending on how strong your willpower is, it’s going to be more or less easy for you to do The 2-Day Fast.

To make it easier you can:

  • Drink water mixed with glutamine (the most common amino acid).

I randomly found out–by experimenting–that glutamine makes longer periods of fasting much easier, without losing out on the beneficial effects.

Glutamine will not activate your digestive system, because it is absorbed in your intestines before making its way down to the gut.

–Just make sure you don’t go over 50 calories at a time (about a full teaspoon).

Glutamine is great for getting a healthier stomach and also for recovering from injuries or sicknesses. For years I had a nasty stomach disease–candida albicans–and my gut would swell up real big and get gassy. Doing 2-day fasts played a BIG part in curing that.

To make the 2-day fast easier you can also:

  • Drink coffee or tea however much you like.

When you combine coffee with the ghrelin-induced dopamine high that hits after ca 20 hours. . .

. . .You get into a state of fanatical focus and single-mindedness.

It’s great.

Recap: Why You Should Go on a 2-Day Fast

The 2-Day Fast is great because:

  • It heals your stomach by giving it time off when you’re not digesting food. (Most people constantly have food digesting in their stomach!)
  • It gets you ripped by switching on ketosis, burning fat effortlessly.
  • It allows for longer periods of hard work and immersion, as your ability to concentrate and learn things gets dramatically heightened.
  • It gives you a natural high, making you feel crisp and clear-headed.
  • It breaks the cycle of incessant stimulation, boosting your self-esteem and sense of personal freedom.
  • It is good practice for breaking out of homeostasis. Improving discipline, metacognition, and mind-body mastery.

Doing a 2-day fast is also good for knowing yourself better. You become better at detecting ways that your brain tries to fool you by means of rationalizations and excuses for why you should eat–and go against your decision to fast. And this ability isn’t just useful for fasting. . .

NOT QUITTING is a crucial skill for any type of success.

To make the 2-Day Fast easier:

  1. Drink about 5g of L-glutamine every 3-5 hours.
  2. Drink coffee or tea. They both suppress hunger and do not contain any calories.

 Common questions I’ve received about the 2-Day Fast


But, I heard fasting is dangerous, and that breakfast is the most important meal of the day?

I’ve heard that too. But it doesn’t make it true. It’s just clever PR and propaganda, made to sell you bacon and cereal.

How do I know if I break the 2-Day Fast and activate my digestion?

You will notice if you break your 2-Day Fast by consuming too many calories, because then your stomach will start to growl and you will get hungry again. You will stop feeling clearheaded, and will start thinking about food instead.

I am afraid to try fasting for so long because I don’t know anyone who has done it.

The stoics did it to practice their discipline. Benjamin Franklin did it. Jakob Walter and other soldiers often did it. And you can check out the comment section of this post for more people who did :-)

How much sleep do I need when I am fasting?

Less than normal.

I can sleep for 4-6 hours when I do a 2-Day Fast and feel fresh still.

Can I end The 2-Day Fast by working out?

I often end my 2-Day Fasts after 40-48h fast by drinking some coffee, creatine, glutamine, and heading to the gym. I usually lift for about 40-60 minutes. This is no problem for me.

I have also tried lifting weights to end longer periods of fasting (50-80 hours), but I find myself becoming physically weaker and fatigued. So I don’t recommend doing that.

Now do a 2-day fast and thank me later.



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  1. “But, I heard fasting is dangerous, and that breakfast is the most important meal of the day?

    I’ve heard that too. But it doesn’t make it true. It’s just clever PR and propaganda, made to sell you bacon and cereal.” – Hahaha XD

  2. Sorry if I missed it but can you drink as much water as you like?

  3. Hi . I tried this 48 hrs fasting several times during the quarantine-since I didnt have to go anywhere. I noticed horrible headaches and inexplicable weakness (I am quite robust and not weak at all). I googled :) and in my next fasting I added 1/2 lime juice and salt (1tsp or more) at “lunch” time (approx.24 hrs fasting)- it worked perfectly! no headaches and no weakness (no hunger of course, homeostasis was beaten hahaha!). Then I started work agian and I had to stop. Now I want to catch up and the main reason is 1. its a great discipline exercise 2. i need to drop much weight (7-8 kg it would be fine on a first stage) Thank you for sharing your knoweledge. I will come back soon with updates

  4. Terry robertson says

    It is my understanding that your body doesn’t switch to Ketosis until between 48-72 hours and is slightly different with each person.

    • Yes, that’s my case for instance. I am not getting into ketosis even after 40 hours water fasting (checked with stripes). But I got all the other benefits anyway

  5. Good post, I’ve been doing I.F. (Intermittent Fasting) for a long time now, it’s helped me stay somewhat lean without even trying. Then I heard about ADF (Alternate Day Fasting). But I think the sweet spot if you’re looking to build muscle and get ripped is to do just one 40-48 hour fast at the end of the week. I plan to experiment with this, by doing I.F. on the days I lift (6 days a week) and then do a 40-48 hour fast for all of Sunday into Monday afternoon (lift first and then eat after). I think I’ll still put on muscle while dropping fat. That could be the only way to do it as a natural lifter.

  6. Great article, and great results! I just finished a weekend (48 hr) fast, after a week of calorie reduction. I found it pretty hard! The first night I slept great even though I felt “hungry”. I ate one “Lara Bar” the second night because my stomach was bothering me so much I couldn’t fall asleep. Nonetheless I lost almost 5 lbs in the 2 days. Also felt very clear and focused some of the time even though my digestive system was complaining almost all of the time. A strong indicator that I am (was) really a bad “food addict” – even though I exercise regularly (mostly endurance training, with some weights). I am looking forward to more of these 2 day fasts to re-regulate my system to see food as fuel and overcome unconscious habits, and to make it easy to maintain optimal weight and get “ripped” as you say. Thanks for the info.

  7. Jordan M Williams says

    Dude, I am 7 days post my first 48 hour fast and I feel like a million bucks. Thank you for this article, this will be something I use very regularly.

  8. You wrote the article completely based on the possible fat burning properties of a fast, not hormonal changes in testesterone and hgh in men. Glutamine is not needed as a suplement unless you’re a frickin’ marathon runner. It’s a non-esential amino acid meaning your body produces it’s own (and it does it quite well).

  9. Thank you.

  10. kristiannie says

    I have done several short fasts in my long life and one extended (60 days) one. My fasts have always been with home made fresh pressed organic juices — mostly green — and my understanding has always been that if you strain all of the solids out of your juice your digestive system will NOT kick in and the nutrients from the juice are just directly absorbed. I have just recently begun 48 hour fasts once a week, using some bone broth and juice but mostly water. It works for me and feels more appropriate for my 68 year old (happy and healthy!) body.

    • That’s different.
      I have little experience with doing juice fasts (never gone over 1 day of doing it), so I wouldn’t know about that.

    • I’ve done a 7 days juice fast and did lose some weight (years ago).

      You won’t be in ketosis though, because of the sugar in the juice, so it’s not the same fat burning effect. Maybe one glass would be ok, but that would defeat the purpose I think. Get nutrients through food on the other days, without overdosing on sugar.

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