[Last updated 27th August 2019]
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:
- It saves me lots of time and money,
- It helps me stay lean,
- It makes me more productive and,
- It gives me much control over my behavior. . .
. . . (since I don’t have to think about food).
Is this hard?
–No.
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.
“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:
- Strive to minimize stress and maintain balance,
- Avoid change and save energy and,
- 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.
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:
- Drink about 5g of L-glutamine every 3-5 hours.
- 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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I also do a weekly 40ish hour fast (typically after dinner Sunday -> Tuesday after workout) and follow 16:8 most other days. I find myself referencing the mental and physical benefits of a weekly 40-hour fast quite a bit in my blog posts because it confers so many of them. For instance, it was Halloween here in America several days ago and I gorged on candy. Yesterday was my fast day, and bam, my body is completely reset and I’m only craving healthy food again. I love it. Keep up the good work, I’ve been enjoying your content for a while now!
Thank you, Dustin!
I guess at the day of the day it’s basic Math. 2 day fast you have saved about 4,000+ calories from your weekly amount. If you were fairly careful the other days you’d always be losing fat.
I can see how after a couple of months the danger is going to be cutting too much.
So do it until you have your fat %…then drop to once every couple of months to maintain. Obviously, you still can’t pig out.
Hey Ludvig, great information!
What are you thoughts about applying this as an ectomorph / skinny? I plan to implement it in the future but I’m a bit worried because being a natural skinny person with a fast metabolism makes harder to eat a lot in one sitting.
Best regards.
I wanted to thank you for your information and I want to try to add something. There is a study regarding a miracle cellular process called Autophagy that most BCAA can kick you out of that process. This process is huge for health and looks to be vital for longevity anti cancer in particular. Eight amino acids, Leu, Tyr, Phe, Gln, Pro, His, Trp, and Met, suppress autophagy but especially Leucine. (http://www.nature.com/cr/journal/v24/n1/full/cr2013169a.html). Glutamine also inhibits as well (http://jcb.rupress.org/content/206/2/173.full). There probably is a slight loss of muscle mass but it appears that 6 steps forward and one step back is a small price to pay. I’m now just starting a 48 hour fast from Saturday night to Monday evening. I’m working out full body 6 days a week with no reps to failure allowed, one 20 reps and one 3 or 4 reps, and lots of protein. We’ll see how it goes.
have you ever experinced bad breathe when fasting, and if so – have you a trick to make it go away ?
bad breathe comes from not having eaten anything you know :)
And how do you calculate how much fat is burned in a fast (ketosis) for 24 hours ? :)
I’m not Ludvig, but I started following IF after reading about it here a long time ago, and have used his 2-day fast method a bunch of times.
I do not experience bad breath (any worse than normal) and as for calculating fat I have no idea…but I have lost a bunch of weight and if I continue I should be semi-ripped in a few months. I do IF every day and 2 day fasts every second week.
I was 43 hours through a 2-day fast today, when something interesting happened. I was feeding my dog, who after taking just one bite of dog food, stopped eating. She came over to me, (sitting down next to her) and sniffed my breath a couple of times. Then she backed up a couple of feet away from the food, looking from me, to her bowl, and back.
This is curious.
((Normally, as she only eats 2 cups of dog food per day during a single meal, she will DEVOUR her food as soon as it is given to her. She NEVER leaves anything left.))
It is eight hours later and she still hasn’t touched the rest of her food. I wonder if anybody has an opinion on this? Do you think she could have smelled the ketones from my breath, and as a group evolutionary trait she was then willing to give up the rest of her food? I am curious to see what others might think.
Regards,
Leland
That’s super interesting. I don’t know much about dogs, but I think your explanation sounds believable. Or maybe she’s copying you?
Yeah, it is certainly (quite) speculative but I thought it was kind of cool regardless.
Cheers,
-Leland
I’m 41 hours and counting into my weekly sesquiday fast. It’s great.
I studied collaboratively this morning with full focus, worked out hard this afternoon, and am going to follow your suggestion and do some more reading and research.
MAN this is some great stuff! I’m trying this out, right now I’ve been fasting for the last 24 hours, going for another day. I can feel the focus running through my brain.
Awesome, I remember how surprised I was at first too!
Thanks for this article and your description of 5:2 with just two days of calorie restriction as being for “weaklings”. I LOLd, and agreed.
I am not going to do your two day fasts (not scheduled, anyway, unless I feel like going over). I am instead going to fast for a sesquiday per week.
Make that I am going to do two-and-a-half-day fasts (scheduled, anyway, unless I feel like going over). I am going to fast for a sesquidupleday per week.
Did you do it yet?
No, I did not!
That is a good question, and was on my mind. While I did a few day and a half to almost two days fasts, never did do the two and a half day fast I planned.
So, I’m changing it to, as a regular thing, eating within an eight-hour window as nutritious foods as viable for me based on circumstances and drive. Was going to do a tighter time-restricted feeding window, but I figured if I’m aiming for the most nutrient-dense foods relative to Calories viable, I could use the extra couple hours to make sure I’m not quasi-forced to eat junk foods to get enough Calories in.
Thanks for posting great articles on other types if intermittent fasting also, and for asking me this question, which psychologically forced me to be accountable for my publicly stated intention.
Am I allowed to chew gum?????
I don’t know.
I have actually never tried.
You will have to see for yourself.
I would not recommend it if it is heavily sugared gum. Sugar, even in small dosages, may well “turn on” your insulin levels (thus making you hungry and ruining the purpose of fasting).
Thanks, I’ll try it with just minimal sugar-free gum and let you know how it goes.
I look forward to hearing about it.
How often should practice 48 hours fast?
Could this also work for a woman?
I read this article some weeks ago and decided I would try it out — and lo and behold you were actually right, I did get ‘*high* after about 15 hours of not eating! Awesome! ;)
I tried it again yesterday but it was too hard and I gave in and ate before I felt anything :(
For a few years me and some friends would to the occasional week-long fast. Not really from a healthy point of view though, it was more to test our limits, and the fast would be broken with lots of alcohol and bruises. Stupidity, but somewhat interesting. Last one I did was for 8 days straight, while studying, definitely had more focus and got lots of work done but was irritable and slow most of the time. 2-day fast sounds great though, how often would you do it? Every week? Great website, and cool to be inspired by another Lundabo!
Hey Johan,
One week? I’ve tried that a few weeks ago — I’m not doing it again anytime soon. Didn’t break it with alcohol though.
How often? for a few months I did it every from Sunday evening to Tuesday afternoon. It would be a 44 hour fast broken with a gym session and a big meal. Now I do it every once in a while. I did it 3 days ago last time.
Glad you like the site.
Wow man. I had a chip on my shoulder because I’d lost 25 kg a few years ago from superlow calorie (200 cals a day) intermittent fasting. Ive always been almost arrogant about my ability about it. Reading this is such a humbling experience. I’m a super-competitive guy, I’m gonna beat you at your feats of will power! haha
I’m increasingly becoming obsessed with the contents and tips of this blog. If you’re looking to create “A movement of like-minded individuals.” as you say. I’m certainly a part of it young man :)
It’s important to be constantly challenging your limits, to be well read, to strive for focus and personal perfection as a way of life, and its very thrilling to read about someone who shares these ideas
Glad to hear it Shaun!
And be sure to let me know when you beat my feats of willpower. Thanks for the email as well.
Nice post ludvig.
Not only is a 2 day fast great for all the above reasons its also great way to prevent getting sick and allowing your body time to recuperate.
Hey Code,
That is my experience too, after having experimented with it about 5 times when I’ve had colds and recovered quickly.
Not sure if it’s a good idea for someone who’s never even done IF (16h+) before though. Perhaps it would just add stress to the body, and mess up the immune system further…
I’m starting today with my first two day fast experiment. Some new research about it, fasting for two days can regenerate the inmune system: http://www.independent.co.uk/news/science/fasting-for-two-days-could-regenerate-the-immune-system-according-to-research-9506168.html
I’m not surprised, Carlos.
There’s a ton of research coming up about fasting lately. At this point, I’m not very interested in it though, because I know that it working well for me.
Another interesting thing about fasting — that I recently learned — is that it can be used to reset your circadian rhythm. This is especially useful for when you want to wake up at a new time in the day. Just don’t eat anything for 20+ hours, then when you have your first meal, you’ll trick your body that you’re starting the day.
Nice. Have you ever tried an all water fast? Did you notice that when you took the 3-5 hour glutamine breaks, it make you foggy-headed/food obsessed again?
Hey Hannah!
“Have you ever tried an all water fast? ”
–I have. And I don’t like its effects as much.
” Did you notice that when you took the 3-5 hour glutamine breaks, it make you foggy-headed/food obsessed again?”
–Nope, and that’s why I take it. But I suppose that can happen if you take it too frequently or in a larger dose than 5g at once.
I much prefer the L-glutamine + caffeine combination to a water fast. That way I am never hungry, and — as an athletic person — I don’t need to be the least afraid of my muscles being ‘eaten’ by the fast even if I am already pretty sore.
What do you think about alternate day fasting? Eating one day and not eating the other.
Hey Vorth,
I couldn’t tell you… I’ve never done it for more than 4 days (1 day eat, 1 day fast, 1 day eat, 1 day fast). But it was fine for that time.
If you decide to experiment with it for 30+ days, I’d appreciate it if you shared your experience!
Wow great read, I have only been been looking into fasting the last few days after seeing a post on FB from a mate who had lost heaps of wait. It was under a post about the UK Doctor/reporter who did the documentary about fasting, he just wrote “this doco changed my life”. After watching it I still had a lot of questions until I found this site. Originally I wasn’t sure but now know I can do 2 straight days once a week. I’m a fat cabbie & have over the last 15 weeks lost 14 KG but it has been getting hard. This I hope will suit my cab driving & maybe sneek a hamburger in once a week :-) I am currently 24 hours into my 1st fast & feeling good & planning to have a sleep (I work nights) & go through until 8pm which will be 41 hours & then plan on doing the 16/8 until I repeat it again next week. one problem I have is I hate tea & coffee so it looks like just water for me or maybe a little diet soup ?? Thanks again & will keep u up to date with how I’m going.
Cheers Mark
@Mark,
Noticed you said you can’t do tea and coffee, but have you ever tried herbal teas? There are hundreds of different kinds ranging from fruity to minty to earthy and everything in between. If you can get Celestial Seasonings teas I highly recommend them.
When I am fasting I tend to get more hunger pangs if I drink something that reminds me of a food, so YMMV.
Hey Mark,
Thanks for the comment.
“over the last 15 weeks lost 14 KG”
— Great job. Keep it up. It’s hardest at first (first 30 days or so) before your body adapts to it. Then you won’t even think about it. You may want to try the water + 5g of glutamine. I always do that during 48h+ fasts.
And I always have some glutamine in the morning ASAP upon waking up (I never have breakfast).
Really nice article Ludvig! I’ve always wondered what really happens to your body when you fast and this answered all of my questions. I started fasting 15 hours ago for the first time and I’m planning on going for 30 hours. I’m wondering if the increased alertness also has something to do with cortisol levels in addition to switching from the rest-and-digest system. There once was a study done on prisoners in which one group of prisoners were constantly exposed to stress (for example a flooded living space) and another group not exposed to stress. When you’re stressed, your body releases this hormone called cortisol which if I remember correctly it provides the body with increased energy taken from the muscles and fat of the body. This goes on until the body runs out of stored muscle and fat. Maybe the body produces cortisol during a fast and in turn leads to ketosis? Just a random thought…
Hey Rui,
Thanks. How did it go with your fast?
I am familiar with cortisol. Yes I think the body produces some amount of cortisol during a fast, but I don’t think it’s the main reason why the body gets into ketosis. Interesting thought though, I will read more on this soon.