What is intermittent fasting?

Three of the most influential
human beings in the history of the world all agreed on one thing… This is the most powerful,
natural healing solution ever. One that’s been used by all cultures
all over the world and one that’s virtually
forgotten today. What am I talking about? Fasting. What is fasting? I can feel your eyes
rolling in your head right now. I get this reaction all the time. You’re going to starve people?
That’s your solution? No, that’s not my solution. Fasting is not the same as starvation. Fasting is the controlled voluntary
abstinence of food for different reasons. You can do it for spiritual reasons,
you can do it for health reasons, you can do it as a political protest…
any reason. It is still called fasting.
It’s not the same as starvation. In fact if you look back
through all of recorded human history people have always fasted. We can start with Hippocrates who is
considered the father of modern medicine. He famously said,
“Our food should be our medicine, our medicine should be our food.” But to eat when you are sick
is to feed your sickness. What is he talking about is this idea
that we have a fasting instinct, that this is something
that we instinctually do. Think about when you get sick. When you have a cold,
when you have a flu, whatever. The last thing you’re thinking about
is eating at a big buffet. It’s something that naturally comes to us,
our bodies are designed to fast. They’re designed to store food
in times of availability and during times of scarcity
to release it. And that’s just what comes
naturally to us and it’s not just us,
but all animals have the same ability. So is not something unnatural, is not something that we’re
just trying to force on our bodies. This is something natural and good. Other people that liked fasting
include Benjamin Franklin, who was world-renowned as one
of the smartest men who had ever lived. What he said was very wise indeed. He said the best of all medicines
are resting and fasting. Now that’s very profound!
Think about that for a second. Resting, which is freedom from stress,
relaxation and fasting which is designed
to cleanse the system, which is what used to be called
the cleanser or purification. Well, those are the two best medicines. Not drugs, not surgery.
Resting and fasting. Amazing! Mahatma Gandhi also said a genuine fast
cleanses the body, mind and soul. Jesus Christ said Satan and his plagues
may be cast out only by fasting and prayers. So if you look at the Christian faith you can see that there are many,
many prescribed periods of fasting all throughout the year. Yes, there are going to be times
when you are going to be feasting or when you’re going to be celebrating,
and that’s balance. But these periods when you’re fasting
to cleanse the body, to cleanse the soul. Buddhist monks also do the same sort of thing,
but they do that on a daily basis. Very typically they’ll fast from noon
until sunrise the next day. So every day there’s
a very prolonged period of fasting. In addition to that they also have
periods through the year when they’ll only have water-only fast and that will help them
cleanse themselves for the year. The Muslim faith has also very profound
believers in fasting. The prophet Mohammed said
fasting brings us to the door of his palace. Many people have heard
of the holy month of Ramadan. During that period Muslims would fast
from sunup until sundown every day for an entire month. All of these religions did not prescribe
fasting to their believers because they wanted to harm them. In fact that’s something
that’s deeply intrinsically beneficial and we know this from the science
that there’s so many benefits. Benefits for weight loss,
benefits for insuline sensitivity, and type II diabetes, for heart disease,
for cancer, for liver disease, and also just to feel better,
for mental clarity. There’s so many amazing benefits. Everybody’s always
worried about fasting. They’re always worried,
“Well can I really do it?” Well, think about this for a second. Consider all these religions, Christians, Muslims, Buddhist, Mormons,
all of these people… All of these people are fasting
on regular basis every year for their entire adult lives. So can you do it? Well, millions and millions
and millions of people do it. There’s no reason why you can’t do it. So there’s lots of people
who will tell you not to fast. Who? Well, this guy, Ronald McDonald,
he doesn’t want you to fast. And this happy little mermaid,
she doesn’t want you to fast. They’re not going to make
any money. Right? They need you to eat.
There’s profits, shareholders, right? In the end you really got ask yourself when it comes to your health,
to your well-being, who are you going to trust? Jesus Christ or Col. Sanders?

100 Replies to “What is intermittent fasting?

  1. Am I right you are assuming that in most cases cells are filled with fuel and therefore don't need anymore?

    I think sometimes the opposite is true: cells asking, craving for fuel but unable to open up due to insulin resistance. How to solve this without metformin?

  2. After I had my daughter I had to go back to work in a busy newspaper.
    I ended up inadvertently fasting because i was still nursing her twice a day and used to run up the hill to my grandparents to feed her and didn’t have time for myself so skipped both breakfast and dinner two days a week (that was my part time job 11 hours tues and wed while the kids were babies).
    Anyway I ended up loosing 5st in weight very quickly and in the end I had to stop because I dropped to under 70lbs.
    Even though it was extreme I released them that the west’s pushing of eating to lose weight was false and that to lose weight you just fasted.
    Such a simple concept that I didn’t realise before because western culture condemns it.
    Obviously now I’m a healthy weight because I had to give the job up due to family commitments otherwise I’d have wasted away.

  3. Thanks Dr Fung, I have a question for you: can you take these 4 supplements and not break your fast (diatomaceous earth, Creatine, L-carnitine and Alpha Lipoic Acid)? Thank you

  4. sooo, how do i protect my gallbladder when i fast because , i think not eating for a while leads to gallstone can you explain how to prevent this please?

  5. How can intermittent fasting cause gallstones and other gallbladder issues?
    take a look at how intermittent fasting affects bile production,
    storage, and release, and how this causes gallbladder problems.
    The liver produces bile, which is stored and concentrated in the
    gallbladder. Every time you eat, bile is released from the gallbladder
    and into the intestines to aid digestion. The liver continues to produce
    bile, which the gallbladder stores again for your next meal.
    As you can see, it’s an efficient cycle.
    However, when you do fasting, at least three things happen:

    The stored bile stays stagnant longer than normal. The cycle gets
    messed up, and the bile gets thicker the longer it stays in the
    Once the liver detects low cholesterol in your system because you
    haven’t been eating, it’s quick to compensate for this lack. It produces
    and releases more cholesterol into the bile.
    Fasting for long hours encourages binge eating. A huge meal stimulates the emptying of bile.

    So what’s that got to do with gallstones?
    Gallstones are made up of thickened bile components. With the
    infrequent flow, it’s like giving bile the perfect conditions to harden
    into gallstones.
    80% of gallstone cases are made up of un-dissolved cholesterol.
    Excess cholesterol in the bile will crystallize in no time and form
    Existing silent gallstones can get dislodged as the gallbladder
    discharges a big flow of bile. Gallstones will go with the bile flow
    toward the ducts. If they’re too big, they can get stuck. That’s when
    the pain starts. Blocked ducts can also result to inflammation and other

    complications of gallstones.

    As you can see, intermittent fasting can have detrimental effects to those
    who already have silent gallstones and those who are at risk of
    developing them.

    Is there a way to go on intermittent fasting even with gallstones?

    If, for some reasons, you have to go on intermittent fasting, you may
    try lowering the hours of fasting to 10 or 12. This will at least allow
    the gallbladder to be more active than it were in the strict IF
    A shorter fasting period will allow your bile to flow more often, but it’s still far from ideal. The risk is still there.

    Majority of people with gallstones suffer no symptoms. It’s highly
    likely that they take well-planned meals and avoid gallstone-triggering
    food. They keep their body fit, exercising moderately and avoiding
    sudden weight loss or gain. They eat small but frequent meals to keep
    the bile moving regularly.
    Intermittent fasting, on the hand, is anything but this. Instead,
    this regimen imposes extreme conditions which will not go well with your
    gallstones. It’s gaining popularity because it’s an easy and passive
    way to lose weight.
    Intermittent fasting can be beneficial for many people,
    unfortunately, it’s not for everyone. Even its proponents acknowledge
    that it’s not recommended for pregnant women, very young children,
    seniors, and people with gallbladder issues.
    It can even worsen your condition and lead to complications of gallstones.
    Surely, you can find a better health program to manage your weight?
    Don’t be afraid to spend more time and effort in it. After all, it could
    mean not having to go through the ordeal of another gallstone attack,
    couldn’t it?

    The question is how long do you fast for within 24hours as we have to empy the gallbladder .. and what type of fasting ….

  6. The Messenger of Allah (peace and blessings be upon him) said that the best of fasts is the fast of Prophet Dawud (peace be upon him), who fasted every other day. [Related by Bukhari and Muslim]

  7. The cringe level in this video was over 9000
    I'm not going to take advice from fictional characters.
    Why not just stick to the science?

  8. I have always had weight issues and started my first diet at age 13, losing 20 lb on a high protein diet. Needless to say, it was the beginning of a weight loss, re-gain plus another 10lb, for the next 45 years. Now weighing twice my weight as i did as a 13 year old, I have finally found something that makes total sense. Last month I re-started my low carb diet, semi-keto, cutting out all processed food and sugars and almost all grains, though occasionally cheating. I lost only 5 lb in one month. Fast-forward to two weeks ago and I finally caved in to pressure from a colleague at work to try intermittant fasting. I started with an 18 /6 a couple of days last week and then a full 24 hour fast with one meal a day. Consequently, I have lost another 15lb in a total of 10 days! I find that fasting during the day at work is easy because I am kept very busy and when I get home I can eat a full meal and feel satiated for the rest of the dangerous evening hours. I am going to see how far this goes. It is very encouraging to see the weight fall off so quickly.

  9. 82 kgs and doing fasting since a week. Sometimes 22:2, sometimes 18:6 but most of the times 20:4.
    Not changes yet but will continue since its a good thing for my body.

  10. Nice vid except for the reference to religion. Getting rid of religion is the equivalent of your mind fasting.

    Since you're all on a journey to cleanse yourself let me share some videos of Theramintree.
    There are jewels of critical thinking that provides delightful and formidable  insights  into the incoherence of the religion.  They are so beautifully made and enjoyable to watch.

    Here are good ones to start with though  I suggest you watch them all on his channel.

    The Impossible Game:


    Punishing doubts:

    Attacking ideas:

  11. I like your videos. Very simple and informative. But you didn’t mention Hinduism, one of the oldest religions who have always emphasised on fasting.

  12. Its rather unfortunate that Dr Chang knows nothing about the oldest civilization from which everything emerged and of all the civilizations it is still alive and self propagating around the world. A degree in a particular discipline does not mean one is educated
    I suggest you should read the vedas and the Bhagwad Gita if you want to quote religion with medicine.

  13. Eastern Orthodox Christians fasts are more than half of the year, only vegan food, and often only raw food. Eating is recommended to happen twice a day during both fasting and nonfasting periods.

  14. It's sad the medical industry is not getting this information out there. I've reversed my type 2 in 3 months eating low carb and Intermittent fasting. I have been following the Dr Berg healthy Keto diet and Dr Jason Fung intermittent fasting. High fat moderate protein low carbs and I have also included fasting eating at 6 pm not eating until next day same time frame 1 meal a day. I am officially by the numbers in normal glucose control anywhere from 80-110 after 2 hours of eating my meals, always on the lower end when I add 40 – 60 minutes of walking 4 days of a week. . I've lost 4.2 KG and feel incredibly healthy. I have recently introduced eating twice in a day and increasing my calories, and I have noticed I am on that higher number end but still good for me at 110. I do not take mitformin or any other medications although they are prescribed I don't need them now that I know how to control with diet and exercise. My last visit I told for my doctor I reversed my type 2 she seemed annoyed I was able to achieve such great results without any advice from her. But when she saw my HgbA1C 5.2 I can see from her face she was surprise. OH! It works for you. Huge thanks to Dr Fung and Dr Berg who are telling people proven methods that actually work.

    Yoseph Ayalew

  15. Great Job! I like the short videos, as I can send to friends and family and give them a “taste” of your theory. The. Pray the dive into the deeper longer lectures to find real truth into the longevity of their health.

  16. Great video, too many distractions on the Doctor’s path. I was also hoping for a clear illustration as you did with your Keto diet video. It was very detailed compared to this. Good video regardless.

  17. I want to know about fasting I try my best but when I try I feel a lot of gas on my stomach what kind of solution should I do


  19. Muslim are supposed to fast besides ramdan every week like every Thursday and every Wednesday…and also 13 ,14 ,15 of every month
    this was every month routain of beloved phrophet Mohammed pbuh …thanx

  20. I fast n eat only 1 lil meal a day,, still not losing weight,, I had thyroid n parathyroid cancer n my thyroid labs r still very bad,,, only thing I can think of why,,, I fast hours by not eating,,I’m not hungry no desire for food,, when I do eat it’s a small amount n only organic n clean,,, So why don’t I look like a starving person?

  21. I am taking fat soluble Thiamine (Benfotiamine) together with water soluble thiamine. I'm now Sixty eight and a half years old, and I'll be sixty nine in January. After a 2 week plateau, I just went from 230 lbs last week down to 225 lbs this morning. Lost 50 lbs since December 2018. Yea! 225 GOING 180! Down from 300+ lbs since last year. Good bye sinus congestion. Good by sleep apnea and snoring. Good bye back ache pain. I F is working. I FEEL GREAT TODAY. Just feed your infirmity and sickness to the fires of ketogenic healing and turn them into energy where they belong! If you get fat instead of feeling this good in the keto diet you certainly don't have to! Stick with it! VIVA KETO!

  22. I eat mostly plantbased food with keto on my way, also IF on my way , i put a personnal Schedule that works with my work, and i have lost 72 lbs (33 kilos) on a year , i feel so good , thanks Doc

  23. Well, three minutes and change into this and still no explanation of what HE feels is "intermittent" fasting and what HE suggests…….is this a TV Show or is He offering some quick tips here?……….OK, now I have watched the entire talk here and no mention of what intermittent fasting is to him or what he suggests. Fasting can be 6 hours, 12 hours, 16 hours and 24 hours. He mentions none of it at all……thumbs down!

  24. A huge believer in the healing power of fasting! Why oh why then do I just want to gorge on food when I am sick? Actually, feeding my sickness was true in the past when I was a carb guzzler. Dr. Fung and Dr. Berg, love you guys for saving my quality of life.

  25. I fast 16 hours every other day.  I have done a day in a half.  My blood sugar is going down fast (went from 490 fasting to 213) in the month I have been doing keto and intermittent fasting.  I went off my insulin pump right away.  I eat carnivore so no carb.  I use the keto strips and can't get into ketogenesis.  I have lost 28lbs during this month.  That is good, but I need to see better results with the weight.

  26. I fast 16 hours every other day.  I have done a day in a half.  My blood sugar is going down fast (went from 490 fasting to 213) in the month I have been doing keto and intermittent fasting.  I went off my insulin pump right away.  I eat carnivore so no carb.  I use the keto strips and can't get into ketogenesis.  I have lost 28lbs during this month.  That is good, but I need to see better results with the weight.

  27. Can you take diatomaceous earth when fasting I have been looking for this information everywhere. could you please make a video.

  28. Doc Fung, inasmuch I believe you and agree with the fasting action, I do however disagree with you for mentioning and bringing religion into this discussion.
    Please abstain from mentioning religion.

  29. Excellent information, thanks doctor for helping us get better without the high cost of the sick care industry. It’s that simple

  30. I want to thank you for the information that just made total sense you saved my life. I went from 306 to 186 I can't thank you enough no more on meds no more diabetes in better health not to bad for a 67 year old…

  31. I'm interested in this, after my doctor recommended it. After watching this video it made me think it's a scam, snake oil. Why? Because he only asserts anecdotal evidence. Jesus said fast so he must be right. He also gave us Leviticus, you know? How to treat slaves, killing your wife if she's not a virgin etc,etc.
    Then to bring up the fact that millions of people follow so many different gods,but they all recommend fasting? Are some of the gods wrong?
    Are all the gods wrong?
    Which God is the most true? What if you don't accept any gods, should you still fast?
    I was hoping for a study with some empirical evidence that came from peer reviewed research. Not, "well this guy said it works so it must."
    I still am trying this, lost 3 lbs so far, but please leave the gods out of your sales pitch. Gotta go, Mr. R. Macdonald is on the phone.

  32. What do I do with my diabetic meds if I want to try fasting, I’m on maxed dose of three tablets..do I stop taking the tablets when I want to fast?

  33. Sir am try this fasting but it is very difficult because there is headache
    For me when am try this fasting i have headache plz suggest me

  34. Wow. I just love this man. He spoke about jesus and mahathma gandhi as examples how to fast. U r great sir 👏👏👏👏👏💐💐

  35. Cannot thank enough Dr Jason for all his videos.I am a totally new person now.I document my journey to help others like me

  36. Awesome video Dr.Fung. I've been fasting for five months and feel and look much better. Better sleep, lots of energy, and weight loss (20 plus pounds). I wish I had found IF sooner.

  37. Who are you going to trust? Jesus or Colonel Sanders?  Well said.  It seems like most of us are trusting the Colonel, the clown, the clown in the box, and that weird (burger) king  these days. Hopefully the people will wake up before our combined obesity tips the earth out of its orbit around the sun.

  38. Hi. Is fasting OK if a person is sick with a mulfuntion kidney? Pls.help. what to do if a person is suffering with kidney failure.

  39. Good information but it did not speak much to intermittent fasting. Neither did the video referenced. Do you have any "How to" videos on intermittent fasting? Thanks.

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