Ask HN: Are You Fasting?
How often do you fast or do intermtten fasting? What do you usually do differently during that time? Does it affect your work? What advice would you give to someone who has just started and is getting acquainted with it?
18 comments
I've been doing intermittent fasting for years now, on a not-so-typical schedule: first meal late in the day (5PM-ish) and the second (final) one within a couple of hours.
What I love:
* Total mental clarity during the first half of the day, can focus fully on work or life responsibilities without a single thought about food.
* Freedom to not have to organize the day around food (making choices, planning logistics, "wasting" time). Pays off big time when traveling.
* Never inconvenienced or slip into grumpy mode when for whatever reason I don't get food.
* Eating a lot of high-quality home-cooked food - as I love cooking (when I have time) and I don't depend on eating out / ordering food / quick-prep meals as much.
* Bonus: great ROI of the occasional first alcoholic drink of the day (on a more or less empty stomach). Not a health advice!
What I love:
* Total mental clarity during the first half of the day, can focus fully on work or life responsibilities without a single thought about food.
* Freedom to not have to organize the day around food (making choices, planning logistics, "wasting" time). Pays off big time when traveling.
* Never inconvenienced or slip into grumpy mode when for whatever reason I don't get food.
* Eating a lot of high-quality home-cooked food - as I love cooking (when I have time) and I don't depend on eating out / ordering food / quick-prep meals as much.
* Bonus: great ROI of the occasional first alcoholic drink of the day (on a more or less empty stomach). Not a health advice!
I find it amazing how much experiences vary. I think a large part of it may be what you eat when you do eat, and also the quantity. Portion sizes seem to vary drastically.
If I fast, I generally get moody and all I can focus on is food. A lot of friends fast for religious reasons too, and the overwhelming majority of them get cranky instead of more productive and able to focus.
If I fast, I generally get moody and all I can focus on is food. A lot of friends fast for religious reasons too, and the overwhelming majority of them get cranky instead of more productive and able to focus.
I think the key is simply letting your body get used to fasting. If you only do it occasionally but usually eat at all the socially "normal" times then of course you're going to be cranky and hungry when you decide to suddenly deprive your body of what it is accustomed to. Eventually, with consistent intermittent fasting, that will change.
I find that if you eat or drink anything with calories between waking up and breaking your fast your body switches mode and wants food. Even a black coffee is risky. Maybe something about ketosis.
I do the same lol, it's great isnt it! I also make an effort to cook my "big meal" myself which is also a great habbit! I use my "lunch break" to go to walk to my local market and pick up ingredients.
I've been practicing daily 16:8 fasting, and on top of that, I incorporate a weekly 36-hour fast from Sunday evening till Tuesday morning. Over time, it no longer hampers my productivity, but I remember experiencing occasional fatigue and hunger the first weeks when I started. Consistency is key during the initial phase, allowing your body ample time to adapt to the routine. So keep going!
I started exactly the same way, one month ago, but it's still difficult to get through Mondays.
I generally do not feel too hungry, especially early in the day, so only ate once per day for years. What a lot of people call a 24h fast I guess?
I felt fine, but BMs got annoying. I now eat twice a day just to keep things moving. And coffee.
I can't say I notice any difference at all in how I feel or weight or anything.
TBH, I don't really consider anything like the above fasting, and have only really fasted I guess once, when I was having a rather bad stomach issue. Day 1 was pain. Day 2 was lethargy. Day 3 felt like some kind of enlightenment. Mentally awake, but I was weak and my brain cloudy. It was a strange feeling of being mentally active but not able to really do anything with it. Maybe my body was giving me faux energy and alertness to go hunt with?
It was interesting, to say the least, but I haven't made a habit of it.
I felt fine, but BMs got annoying. I now eat twice a day just to keep things moving. And coffee.
I can't say I notice any difference at all in how I feel or weight or anything.
TBH, I don't really consider anything like the above fasting, and have only really fasted I guess once, when I was having a rather bad stomach issue. Day 1 was pain. Day 2 was lethargy. Day 3 felt like some kind of enlightenment. Mentally awake, but I was weak and my brain cloudy. It was a strange feeling of being mentally active but not able to really do anything with it. Maybe my body was giving me faux energy and alertness to go hunt with?
It was interesting, to say the least, but I haven't made a habit of it.
No, but I eat in the evening at 7pm then don't eat/just have water until breakfast at 7am, after I have been to the gym for 60mins.
I have lost 30lb since 01/01/2023. Just cut out junk, reduced portion sizes & only drank alcohol at weekends.
I have lost 30lb since 01/01/2023. Just cut out junk, reduced portion sizes & only drank alcohol at weekends.
Same, but with long walks instead of gym time!
This year I decided to try fasting during Ramadan, as I was visiting a Muslim country and all my friends there were doing it. It was pretty interesting to eat the first meal around 4:30a, fast all day (no food, no water, no anything), and then eat again around 6:30p. I also didn’t drink any alcohol during the month, partially because one couldn’t buy it. I accidentally developed a bit of self control, and now controlling what I eat & drink seems to be a bit easier.
Yes, I'm an Orthodox Christian so bit more than half of the year is fast day. Fast day means that I eat vegan food moderately (with some exceptions, like fish allowed on some days) and also don't use oil when cooking. There are four longer lent periods around the year and each Wednesday and Friday are fast days. Although after some big feasts and before the Great Lent (which is before Eastern) there are weeks that are fast free.
At the beginning of Great Lent there are also three days that I try not to eat anything but usually it's not possible for me because of work, so I pick something small in the evening. Also during Great Lent I don't eat breakfast (to not break my fast ;)). Oh, and on Sunday if I attend Eucharist in the church I don't eat and drink anything before that.
Trying to follow these rules gives me a lot of joy and rhythm to my life. It makes me appreciate food, and also has made my diet simpler also in days that I'm not fasting. But the point isn't to restrict food but to be able to focus more on the spiritual struggles and tame your passions.
At the beginning of Great Lent there are also three days that I try not to eat anything but usually it's not possible for me because of work, so I pick something small in the evening. Also during Great Lent I don't eat breakfast (to not break my fast ;)). Oh, and on Sunday if I attend Eucharist in the church I don't eat and drink anything before that.
Trying to follow these rules gives me a lot of joy and rhythm to my life. It makes me appreciate food, and also has made my diet simpler also in days that I'm not fasting. But the point isn't to restrict food but to be able to focus more on the spiritual struggles and tame your passions.
As a Muslim, this is so interesting. Fasting is such a big part of Islam too, with Mondays and Thursdays being recommended fasting days. Different implementations, sure, but very similar idea and also gives me rhythm in life plus focusing on the spiritual self. Thanks for sharing!
I have tried multi-day fasting several times. Painful to start, but it feels OK in the middle of it, and it feels great after it's finished (works best when immediately followed up by a keto diet, I recommend a vegan keto one, to avoid nasty things).
Below 48h of fasting, you don't enter ketosis, so you miss out on many benefits.
But never stop drinking water througout any type of fasting.
Below 48h of fasting, you don't enter ketosis, so you miss out on many benefits.
But never stop drinking water througout any type of fasting.
> Below 48h of fasting, you don't enter ketosis, so you miss out on many benefits.
We are all different, but I am pretty sure you can enter ketosis after 18-20 hrs fasting
We are all different, but I am pretty sure you can enter ketosis after 18-20 hrs fasting
Your liver has a ton of glycogen that it has to go through before being depleted and starting ketosis.
It takes between 18h and 24h to deplete the liver, but that is without taking in consideration the contents of the GI tract! There are plenty of carbs and proteins in the GI tract at any time, and that takes around 1 day to digest too.
So I don't know how you managed to shortcut all of that, but I'm extremely interested!
It takes between 18h and 24h to deplete the liver, but that is without taking in consideration the contents of the GI tract! There are plenty of carbs and proteins in the GI tract at any time, and that takes around 1 day to digest too.
So I don't know how you managed to shortcut all of that, but I'm extremely interested!
I am just parroting back what I read online. When I diet I am pretty strict and full on about it but I dont take ketosis measurements
My weight loss IF diet is 20:4. Keto is just raw or cooked food including raw healthy oils. I completely avoid risky foods marketed as keto friendly.
Once optimal weight is achieved I switch to 16:8 and swap keto for mediteranian diet
My weight loss IF diet is 20:4. Keto is just raw or cooked food including raw healthy oils. I completely avoid risky foods marketed as keto friendly.
Once optimal weight is achieved I switch to 16:8 and swap keto for mediteranian diet
Yea, I read the same, and what about autophagy? (As I know you can enter it after 26-30hrs fasting)
Autophagy as in "eating your own proteins" starts when you have no more fats in your body... That takes weeks usually, unless you are already exceptionally skinny.
Until then, it's autophagy as in "converting adipose tissue into energy stores", so you're safe. And I don't think we use "autophagy" for this meaning.
Until then, it's autophagy as in "converting adipose tissue into energy stores", so you're safe. And I don't think we use "autophagy" for this meaning.
Autophagy refers to a "recycling" cellular process: https://en.m.wikipedia.org/wiki/Autophagy
Another thing not to forget: you need not only water, but minerals with it (sodium, potassium, magnesium...). There was a time when I did not pay attention to this and fasted with water only - the result was very bad sleep and muscle cramps, which are quite scary. Also I lost all my flexibility for a short time. Maybe others are not so sensitive to this, I certainly am.
Vegan keto might be the worst to recommend after fasting, the best / easiest to digest are fats, so a quality broth to break the fast without breaking your digestive tract is what works for me. But I agree that after a multi-day fast keto just comes naturally and easily.
I don't know why you are saying this, like there are no plant-based fats?
There exists so many plant oils, olive oil, nut oil, etc. Avocado is also almost only fat.
In meat-keto, you'll eat saturated fats, maybe heated fats, read meat maybe too (bad for CVS), most probably a ton of sodium... no thank you.
There exists so many plant oils, olive oil, nut oil, etc. Avocado is also almost only fat.
In meat-keto, you'll eat saturated fats, maybe heated fats, read meat maybe too (bad for CVS), most probably a ton of sodium... no thank you.
How do you eat olive oil, for example? Don't tell me you pour it in a glass and drink it :) Typically people eat it with raw vegetables (ie. as a salad), which is very taxing on a digestive tract that has just been cleared of gut bacteria. Fiber is your biggest enemy in this specific case.
Saturated fats are not the enemy, but I guess I won't convince you of that. Red meat? That's the best. Heated fats??? Yes, it's a broth, it will be cooked for hours, if not days... I usually make it with bones of beef, and very little salt, definitely not a ton. Also, because it is bought as raw meat / bones, no other preservatives are added. Another question could be what that poor cattle had been eating, quality meat is certainly not cheap, and you need to pay attention to where you buy it.
Another option is chicken broth, that's more protein though, and no bone marrow.
Either way, the first sips of broth after a week of fasting taste like heaven, and you also don't need a lot (maybe a deciliter?), still you will feel completely full and well fed. I love this feeling!
Saturated fats are not the enemy, but I guess I won't convince you of that. Red meat? That's the best. Heated fats??? Yes, it's a broth, it will be cooked for hours, if not days... I usually make it with bones of beef, and very little salt, definitely not a ton. Also, because it is bought as raw meat / bones, no other preservatives are added. Another question could be what that poor cattle had been eating, quality meat is certainly not cheap, and you need to pay attention to where you buy it.
Another option is chicken broth, that's more protein though, and no bone marrow.
Either way, the first sips of broth after a week of fasting taste like heaven, and you also don't need a lot (maybe a deciliter?), still you will feel completely full and well fed. I love this feeling!
What do you even eat on vegan keto? What’s left when you get rid of animal products and carbs - nuts and plant oils?
On the fats side, yes exactly, plus avocado.
But you forget easily that keto is not eating only fats. You can take reasonable amounts of proteins too (lentils, soy...), tons of fibers (salad, cabbage, celeri, any leaves basically), ...
But you forget easily that keto is not eating only fats. You can take reasonable amounts of proteins too (lentils, soy...), tons of fibers (salad, cabbage, celeri, any leaves basically), ...
Plant protein comes along with carbohydrates, you can only have so much until it's not keto anymore. Fiber, schmiber - you need calories and protein to live.
I eat my dinner at ~19:30 and then lunch at 11:45. This is 16 hours of fasting every day.
Why? Because I am not hungry in the morning and the canteen opens at 11:30 (and there are less people then - I am in France where between 12:00 and 13:30 the world stops and everyone is downstairs queuing up to eat).
The effects? From 101kg to 85kg with 3% fat. Just kidding - I did not see any difference and I am still overweight (despite biking and eating healthy - this is probably one of these rare cases where thyroid-induced metabolism is the main culprit).
I also followed (and plan to follow again "~tomorrow") the JFEH diet. It works great (JEH stands for Just Fucking Eat Half (TM), a Scientifically Sound Diet (C) where you eat about the size of your fists put together). I really need to get back to that.
Why? Because I am not hungry in the morning and the canteen opens at 11:30 (and there are less people then - I am in France where between 12:00 and 13:30 the world stops and everyone is downstairs queuing up to eat).
The effects? From 101kg to 85kg with 3% fat. Just kidding - I did not see any difference and I am still overweight (despite biking and eating healthy - this is probably one of these rare cases where thyroid-induced metabolism is the main culprit).
I also followed (and plan to follow again "~tomorrow") the JFEH diet. It works great (JEH stands for Just Fucking Eat Half (TM), a Scientifically Sound Diet (C) where you eat about the size of your fists put together). I really need to get back to that.
I'll apply the JFEH for sure :D
I'm muslim and I do fast on mondays and thursdays. I feel much better during the day and also more focused. Following as how it is done in islam (no food, no water) I take breakfast before the sunrise (right now where I live is around 5am) and then after praying (similar to meditation in terms of benefits) I start to work.
I can think really clearly vs the days that I don't fast and also I would say that my productivity is higher in terms of what I achieve. It has the downside that at 5PM or around I'm already without energy and I stop working compared to normal days when I'm okey up to 11pm.
I also pray 5 times a day as is usual, I'm not sure if that is relevant as afaik it has been found to have similar effects to meditation.
Finally I eat dinner and drink around 9PM
I can think really clearly vs the days that I don't fast and also I would say that my productivity is higher in terms of what I achieve. It has the downside that at 5PM or around I'm already without energy and I stop working compared to normal days when I'm okey up to 11pm.
I also pray 5 times a day as is usual, I'm not sure if that is relevant as afaik it has been found to have similar effects to meditation.
Finally I eat dinner and drink around 9PM
I do 72hrs from Sunday to Weds night (I finished 10 mins ago!).
Instead of food I hit the gym or walk the dog. My work is improved IMO - I'm faster, more alert and find it easier to problem solve and focus. I'm a CTPO for a finance and payments company so if it was a negative, I'd know pretty quickly.
Happy to connect/chat about it -- even if it's for accountability
Instead of food I hit the gym or walk the dog. My work is improved IMO - I'm faster, more alert and find it easier to problem solve and focus. I'm a CTPO for a finance and payments company so if it was a negative, I'd know pretty quickly.
Happy to connect/chat about it -- even if it's for accountability
How long have you been following this for? What's your motivation?
I've been following a similar schedule (72-96h during weekdays, social activities permitting), primarily for weight loss, but I'm surprised with with how productive I feel compared to normal or even time-restricted eating.
I've been following a similar schedule (72-96h during weekdays, social activities permitting), primarily for weight loss, but I'm surprised with with how productive I feel compared to normal or even time-restricted eating.
I've been doing it a while and was previously doing Sunday to Tues morning. Me and my partner did Sunday to Friday a few months ago for a wedding and have been sticking with 72 pretty well.
I hit age 40 soon and I think my metabolism has slowed a lot, I still weightlift and run but there's definitely been a shift in what I can eat and stay comfortable with
I hit age 40 soon and I think my metabolism has slowed a lot, I still weightlift and run but there's definitely been a shift in what I can eat and stay comfortable with
"Wait till you are actually hungry" seems to work fine. It is extended version of @Jack's "I eat only once a day", except there is no rules.
Interestingly first thing they teached to American Injuns, was "warm meals thrice a day" and the result can be seen in the Indian population even today.
Interestingly first thing they teached to American Injuns, was "warm meals thrice a day" and the result can be seen in the Indian population even today.
First meal around noon, last around 6PM (18:6 they call it I guess). No eating out, only cooking at home, and no alcohol. Together with some exercise (running 4x a week) lost 7kg in 3 weeks. Sleep has improved dramatically. If you feel hungry, just drink a large glass of water (400ml).
I do 16hrs fasting from 8 pm-12 noon the next day. I keep it after work, starting with an early dinner.
Wow! I do exactly the same thing. Keeps you lean and mean
I do something similar, but I have a late breakfast (like 10:00-ish, second meal is at 16:00 or latest 18:00).
I fast, not intermittent fasting but real fasting, 48 hours or 72 hours or longer depending on social obligations, during parts of the year. I might be the only one who does this so I hope my testimony helps you out.
During these fasts I have water and nothing else. If I feel inclined to exercise or if I'm peeing excessively I will take electrolytes in the form of powder in water, but that's it. In the morning I'll have black coffee. So technically this is called a "dirty fast".
Initially it sucks. The first day in particular can be a bit hazy. Tip of tongue syndrome, tendency to hyper focus on a single thing, etc. It is objectively terrible.
After about 24 hours it becomes a very smooth feeling and you feel mentally agile. It might be placebo but it feels like more mental agility than when not fasting.
After about 48 hours it becomes peaceful on top of all that. Forgiveness comes easier, anger comes slower, you will feel like you should do less harm, things like that. It's a bit of a trip. Hunger is still there, might even be roaring with hunger at this point. Sense of smell is greatly sharpened.
After 72 hours you no linger are hungry. It's scary. There is just no desire to eat other than a psychological worry that you're missing whatever vitamin you're recently obsessed with. You might ask yourself "what's happening to my nicotinamide riboside reserves" and other such questions. However, physiologically there is not much hunger at all, and it is a bit scary because you know that you need food so it's strange and makes you mistrustful of your impulses to experience a disconnect between instinct and need.
Beyond 72 hours it stays the same, you've evolved beyond needing food and bowel movements and are closer to machine, you can get a lot done and you will have more time than you know what to do with. If you're someone who enjoys indulging in earthly pleasures you might be extremely bored.
Disclaimer the following contains information about fasting, it is not qualified medical advice as I am not a doctor nor am I claiming that it is safe:
My "advice" to someone who has just started is to take it slow, primarily for medical reasons. Electrolytes aren't exactly safe to tinker with. If you have a heart condition I would say straight up don't do any extended fasting. However if you want to know how it feels like to fast then work your way up to an extended fast, try an all day fast then resume regular eating for 3 days then try again. Then work up from there. Don't become obsessive about whether one calorie from sugarless gum breaks a fast, focus on the discipline required to fast through meals and let that discipline strengthen other aspects of your life. Also, take a very thorough accounting of your own health. If fasting causes you to lose minerals, you should be able to notice it right away. Take careful care of your teeth and nails so you can see any potential warning signs before they become issues. If anything goes wrong just resume eating, there is always tomorrow. And remember that water is your friend but if it is absorbing too much electrolyte out of your body then use powdered electrolytes to stay balanced.
Lastly, in general, and in stark contrast to the above, I do NOT recommend fasting to most people unless they hunger for a challenge that requires immense self-discipline. You can get plenty of metabolic health benefits from IF or OMAD without nearly as much discomfort. You can say "I'm fasting" and simply skip breakfast or dinner. It's almost a no-brainer especially if your only goal is weight management.
Source: me about to be 72 hours fasted
During these fasts I have water and nothing else. If I feel inclined to exercise or if I'm peeing excessively I will take electrolytes in the form of powder in water, but that's it. In the morning I'll have black coffee. So technically this is called a "dirty fast".
Initially it sucks. The first day in particular can be a bit hazy. Tip of tongue syndrome, tendency to hyper focus on a single thing, etc. It is objectively terrible.
After about 24 hours it becomes a very smooth feeling and you feel mentally agile. It might be placebo but it feels like more mental agility than when not fasting.
After about 48 hours it becomes peaceful on top of all that. Forgiveness comes easier, anger comes slower, you will feel like you should do less harm, things like that. It's a bit of a trip. Hunger is still there, might even be roaring with hunger at this point. Sense of smell is greatly sharpened.
After 72 hours you no linger are hungry. It's scary. There is just no desire to eat other than a psychological worry that you're missing whatever vitamin you're recently obsessed with. You might ask yourself "what's happening to my nicotinamide riboside reserves" and other such questions. However, physiologically there is not much hunger at all, and it is a bit scary because you know that you need food so it's strange and makes you mistrustful of your impulses to experience a disconnect between instinct and need.
Beyond 72 hours it stays the same, you've evolved beyond needing food and bowel movements and are closer to machine, you can get a lot done and you will have more time than you know what to do with. If you're someone who enjoys indulging in earthly pleasures you might be extremely bored.
Disclaimer the following contains information about fasting, it is not qualified medical advice as I am not a doctor nor am I claiming that it is safe:
My "advice" to someone who has just started is to take it slow, primarily for medical reasons. Electrolytes aren't exactly safe to tinker with. If you have a heart condition I would say straight up don't do any extended fasting. However if you want to know how it feels like to fast then work your way up to an extended fast, try an all day fast then resume regular eating for 3 days then try again. Then work up from there. Don't become obsessive about whether one calorie from sugarless gum breaks a fast, focus on the discipline required to fast through meals and let that discipline strengthen other aspects of your life. Also, take a very thorough accounting of your own health. If fasting causes you to lose minerals, you should be able to notice it right away. Take careful care of your teeth and nails so you can see any potential warning signs before they become issues. If anything goes wrong just resume eating, there is always tomorrow. And remember that water is your friend but if it is absorbing too much electrolyte out of your body then use powdered electrolytes to stay balanced.
Lastly, in general, and in stark contrast to the above, I do NOT recommend fasting to most people unless they hunger for a challenge that requires immense self-discipline. You can get plenty of metabolic health benefits from IF or OMAD without nearly as much discomfort. You can say "I'm fasting" and simply skip breakfast or dinner. It's almost a no-brainer especially if your only goal is weight management.
Source: me about to be 72 hours fasted
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I do the "stop eating 3 hours before bedtime" version when I can, which seems fine.
For 24h fasts, I recently learned that fasting from breakfast to breakfast, instead of, say, dinner to dinner, doesn't mess up my day night cycle, like the other alternative does. The breakfast seems to strengthen the body's feeling of it being a new day.