Benefits of Fasting for Weight Loss Put to the Test

Benefits of Fasting for Weight Loss Put to the Test


  • Daniel Lugo says:

    please can you link all articles you take as a reference? i would like to read the full studies…

  • Mrssewhardtoplease says:

    Didn't work for me and I did it correctly.

  • freethinker52 says:

    why do people need a gimmick? just eat nothing but plants. maybe eat less plants if you want too lose a few. you will lose weight. no need to put your body through the dangers of starvation.

  • Lloyd Christmas says:

    Thanks Dr. Greger.

  • KK says:

    It's safe doc. It's safe. Don't take this away from me 🙁

  • ralph hancock says:

    I like the notion of fasting, simply to break up bad eating patterns, if nothing else. As for sustainability, I see fasting as an intermittent disruption, just like running is. I can't run all the time, but certainly intermittently. If intermittent running is a "lifestyle" choice, so too with fasting. Be a runner or be an intermittent dieter. An "unsustainable" choice?

  • Purple Carrot says:

    hold up hold up. How can you survive for 382 days without protein? I understand he gets energy from his fat, takes vitamin and mineral supplement, but what about protein?

  • Purple Carrot says:

    I think enhanced mood comes from ketosis? While I was in ketosis I experienced this feeling of euphoria and incredible mood.

  • Tito V says:

    Great post Dr.!

  • ralph hancock says:

    Aside from the life style choice issue, I do have concerns that fasting will screw up your system from lack of nutrients and messed up biota. Check out the responses to the Quora question "What's the effect of prolonged fasting in gut flora?"

  • Shari T says:

    '…in 1915 two Harvard docs indelicately described 2 extraordinarily fat women…one of whom was a veritable pork barrel' I lost it! Indelicately, indeed!

  • Kristopher Williams says:

    Intermittent fasting has become another lifestyle choice, along with Vegan. Some days I cut the fast early, some days I will eat later, but generally I stick inside the 16:8.

    I typically consume 1,600-2,000kcal with regular exercise and my weight will fluctuate between 152-156lbs. Gives me a healthy baseline and an easy template to work with if I want to built strength or focus primary on endurance.

    It was amazing to see that the weight was under my control with focus on the habits of eating. Going vegan 6 years ago, I had this idea I could eat whatever I wanted, and weighed ~ 165-170lbs. Since then it has been a refining process

  • michael onello says:

    Great video……Thx

    Vegan whole plant based foods on Instagram == mikewakethefoodup

  • Giovanny De Jesus says:

    Food industry frowns on fasting.

  • Kjartan Ofstad says:

    Yeah no. Nothing wrong with eating food

  • israr asif says:

    pls stop making weird noises arrrr uhhhhhhh so annoying

  • Y says:

    I knew a girl who did I guess it was considered a liquid fast for a few months. She was obese already. She did this fast with her doctor’s supervision too. She saw the doctor I think every week or so. The doctor had her on ensure and some weird smoothies (and not fruit and veggies smoothies, I think powders or something) 🤷🏻‍♀️. She did lose so much weight! I mean so so much! But then I recently saw a foto of her at a family event and unfortunately she gained all of it back, plus 3x more weight than what she was. I couldn’t believe it 😪.

  • paul w says:

    Prahlad Jani for the win…..

  • Kit Rimes says:


  • Adnan A says:

    I need to start fasting more

  • GlitchLife says:

    FINALLLY!! Drag your feet for years Mike, SERIOUSLY!!!! BOUT DANG TIME YO!

  • Steph Ss says:

    I use to intermittent fast, then I had heart problems (arrhythmia and palpitations) and my metabolism tanked so I gained twice as fast. Now I eat dense low caloric foods, and exercise. When I use to fast the brain fog from the lack of glucose was so impactful that I would have serious memory problems, and was so low energy that I would nap, non stop during the day. Unless I was having seizures, or stranded somewhere, I am never fasting again.

  • Dave E says:

    Fasting vs intermittent fasting. 2 different things. Don't conflate the 2 to bash IF

  • Hikingphotobug says:

    This is interesting stuff and I enjoy all of these videos!
    As far as the euphoria in fasting, it might help explain the 'hook' in the mirror side of obesity – anorexia eating disorders. Eating disorders have, of course, a starting point with the perception of food, eating and body image coupled with the endorphins that can contribute to underlying compulsive/obsessive eating issues. That is a whole other discussion. I think where I'm actually going here is that it is important to mention and address all of the eating disorders. Obesity related eating disorders and Anorexia eating disorders are both very damaging to the body in a functional and nutritional context. Unfortunately, one is shamed and the other is praised.

  • Fifi says:

    NutritionFacts is not an official website. It’s a propaganda site for vegans and is managed by this guy

  • SpiritualVegan says:

    Stick to a healthy WFPB lifestyle and exercise rather than eating whatever and then starving yourself. We all fast in our sleep, prolonging the fast is just gonna make you binge later to make up for the lost calories and glucose. I won’t be draining my glycogen stores anytime soon.

  • iChefTheImpossible says:

    Damn cliffhanger

  • SulforaphaneMeUp says:

    Is it safe? We know the scientific community can't say it is no matter what because of the liability. Most responsible people with knowledge will suggest it is only safe under medical supervision. Most people can't afford to be under medical supervision for their weight loss. One even created a way to cheat the effects by eating the bare minimum over a week or so. It is a good topic to resolve though and hopefully it is solved before too many people go too far. For myself I fast about an avg of 18 hrs per day. I feel fine but wonder if it is the best solution. I am not overweight but just want to be as healthy as possible.

  • Alan Angel says:

    Man you are so careful about what words and subject you avoid. No mention of the fasting reducing insulin/blood sugar levels. No mention of the body producing and using more ketones during a fast. A bit too keto I suppose. …

  • John Zaskoda says:

    Please do a video on dry fasting.

  • UPRISING 144K says:

    This is great info. However, fasting is very difficult for most people and sometimes unrealistic for people who have busy lives. The crazy thing is, there is a way to get the benefits of fasting, without fasting. Check out the unusual effects of molecular hydrogen water on the body and how it mimics fasting. And it has other amazing benefits. If you or anyone wants any links, let me know and I could possibly share some.

  • Simon B. says:

    Ah! Finally the fasting-videos come rolling in!

  • Mike Gibson says:

    I used to be sick so frequently that I decided to replicate a study on mice which the researchers said rebuilt the immune system (MICE being the key word here but I was sick so often I didn't care). Essentially water fast 2-3 days once a month for 6 months. I did that, and it seems to have worked. I went from sick 10+ times per year to 1-2 times per year. I think that was 4-5 years ago now. I'm hoping those studies will be covered in future videos.

  • Rachel P says:

    I did alternate day fasting for 7 days, eating 1800 calories on non fasting days. I gained 12lbs. I think it might work if you actually overeat and that's why you're fat. But that's not always why people are fat. I once "fasted" for 4 months, it was called anorexia nervosa. I lost 120lbs, a kidney, and my gallbladder.

  • Laura Eternal says:

    I love fasting except it made gallstones worse

  • Stuart Hawkly says:

    A veritable pork barrel?!! Hahaaaa this fuckin' guy

  • truefuschniken says:


  • j mc says:

    ⚠️⚠️warning do not take Zantac (ranitidine). Just recalled for causing cancer!! Canada was last to know.

  • Dark Flamingo Pontificates says:

    How do people feel about fasting once or twice a week?

  • Cerenade Me says:

    Please address the health benefits of water-only fasting, rather than fasting for weight loss. Thanks!

  • fire7side says:

    I used diet alone to get down to within about 20 lbs of my bmi normal weight. I couldn't seem to make any more progress until I tried fasting one day a week and I was down to bmi normal within about 3 weeks to a month. I've kept if off just fine without doing any more except one time a partial fast of skipping breakfast and supper. It definitely helped me get control of my hunger. That and getting all the sugar, fake sugar, etc out of my diet. I can easily wait an extra few hours for my scheduled meal now sometimes going 8 hours between meals.

  • Aria Invictus says:

    If it wasnt for fasting, i doubt i would be on a whole food plant based diet. Yeah fasting is temporary, but it helps reset the palatte somewhat, and that helps eating previously less favorable taste to plant foods, especially greens, much more tolorable.

  • Doug bananaboy says:


  • TheRoshan says:

    All the women on the online dating websites seem to be veritable pork barrels

  • Nathan Kopilec says:

    Didn't know "veritable pork barrel" was considered scientific terminology 😂

  • maremacd says:

    The Fasting Fatman (he has a YT channel) is currently on his second extended water fast. His values don’t align with most on this channel (he tried and like the carnivore diet during a break from full fasting, for example), but his resolve is pretty amazing.

  • I’m_Lonely You’re_Lonely says:

    Lol. At people think they’re made differently because no diet works lol. Hilarious. I’ve heard females say this the most. Including my mother.

  • christoffer pedersen says:

    ending with a cliffhanger …🤣

  • amywjn says:

    What does fasting do to muscle mass & metabolic rate?

  • tamcon72 says:

    I aspire to an existence of "exceptional usefulness" myself, ha-ha! This was a real eye-opener; hope there are more assessments of recent fasting research upcoming. TFP!

  • Luna Lovebad says:

    While I enjoyed the fasting information in this video, I wish we could do away with the casual fatphobia. If a study from 40 years ago had referred to an ethnic minority population in a prejudicial manner, we wouldn't think of including that in a video. And yet, the inclusion of the damaging remarks by the medical community describing an obese woman were included for laughs. I urge you to reconsider this.

  • mmmollie27 says:

    I have done IF for some time, but I fell off the wagon and now I can't get back on it. I struggle and fail daily. I normally plan to break fast at 12pm but end up getting really hungry around 10am (I am normally up at 5am). And it just goes downhill from there.
    Any ideas on what I could change? Improve on? Any methods or routines that work very well?

  • Alec Gargett says:

    No calorie-deficit weight loss diet is sustainable. It doesn't need to be. The important thing is whether it's healthy not whether it's sustainable. Looking forward to you actually discussing whether it is healthy.

  • Nico Rob says:

    Could you talk about taurine?

  • U WUT M8? says:

    so fasting is the gateway drug to a better life

  • Thicc Vegan says:

    OH GOD COME ON!!!!!!!!!!!!! 🙂

  • Vegan Artist says:

    I hope you go into more detail in your video about the effects of fasting for men vrs. women. As far as my understand goes, a lot of studies have researched men on fasting diets but not women. And as such, at this point we don't know the effects that fasting can have on women's hormones, especially in non-obese/ healthy women. From my own personal experience and bias ( as a non-obese woman) stupid enough to think water fasting would have beneficial health benefits, I found the process to be far more damaging to my body than I was led to believe. It took months for my body and hormones to normalize afterwords.

  • Plantbased Outdoors says:

    382 days???????????? I can't even fast for 382 minutes.

  • roberto R says:

    I’m watching this while eating a huge peanut butter sandwich

  • Raphael Quaglio says:

    Deficiency in vitamins & electrolyte imbalances is not healthy. Fasting every day for 20 hours is not good. Better to fast for 2 days with 2 days of replenishment & feeding. Long term fasting for a week or more is not healthy, even with supplements. Supplements are synthetic vitamins and no substitute for real food.

  • Fernando Fidalgo says:

    "We'll find out……… NEXT!" 😳

  • IAM REAL says:

    Think the study shows something else very important… that obese people can go without food very easily, yet I am sure they all put much of it or more back on. IMHO some of us dont have an OFF switch (Perhaps our genes as we advanced turned of the constant craving for food (which we used to need for survival) but it didnt get turned off for all of us).. I am not obese…but struggle all the time to maintain a healthy weight. I can go forever with no eating…but once I start… I cant stop. Seriously

  • The Artificial Society says:

    I guess if we starve ourselves, we can lose weigh. I think thats a good research topic for seventh grade. Does it really take a Phd to figure that out?

  • T Burke says:

    So timely… I have been reevaluating my fasting practices and have some additional clarity about the direction I am heading in. Thanks Dr. Greger!!! 👏🏾👏🏾👏🏾

  • Bill Ding the constructor says:

    I dont get how you calorie restrict when you calorie restrict you get really hugnry. even if you eat a lot of vegetables and fills up on it, i still "crave" like in my throat and mouth calories from potatoes, beans, rice etc. any tips? i wnt to get the health benefits pls. but i feel like a failure.

  • BeeRich33 says:

    "Booda". My first 5-day fast had 3 days of detox, which resulted in headaches. Day 4, however, it all cleared up and I had stupendous energy. Day 5 had settled down and very clear head. I do 4-day fasts from time to time, should do one next week. That chart demonstrates a 50% increase during fasting. I'd rather a regime of plant-heavy diets. "Eat To Live" by Dr. Joel Fuhrman lays out all the groundwork for this. Lost 30 pounds in two months, while weekend "cheating" and drinking beer during all this. Hehe.

  • Jeff Hinzman says:

    I just had my first “I can’t wait for the next episode” moment on YouTube. C’mon man! Who shot JR? Who did Sam call on Cheers? Did Riker kill Borg Picard? This video is officially in my top ten of season cliffhangers.

  • ampoules1 says:

    Dr. Cliffhanger

  • Mouse says:

    I find that fasting and intermittent fasting helps with my binge eating disorder and helps me not gain any more weight. I can go without food for 24 hours every single day and sometimes even 48 hours or more. When I do eat binge-eating episodes don`t occur cuz I only eat when accompanied since I`m completely unable to control my food intake when I eat alone. I almost feel like a normal person without an eating disorder when I force myself to fast for hours or days. Otherwise I`d be snacking on nuts, dates, fresh apples, tomatoes, rice, buckweat, oatmeal, garlic, kale etc. until I feel too stuffed to walk, gain a lot of weight and end up constantly criticizing my body. Fasting also reduces my hunger so that I don`t eat too fast when I finally eat my family dinner. So, for me personally fasting works very well.

  • Alexander K says:

    Thank you, next!

  • martin craughwell says:

    Wow 382 days! That's insane! How much weight did he lose?

  • Astera Kh says:

    We as muslims fast for a month from sunrise to sunset in each year

  • zwady says:

    Intermittent fasting shouldn’t be done daily. It should be done intermittently. Twice a week for example.

  • Huge4Guitar says:

    Everyone celebrating? I am sure he blows up fasting in next video🤦‍♂️

  • jbidwell605 says:

    I went to a fasting clinic in Germany. The national health insurance pays for it and it is quite common there. Wish the rest of the world would jump onboard with this already.

  • amo says:

    Fasting is used also by animals when they are sick and injured.

  • Chad says:

    Fun fact… Fasts as short as 24 hours are ketogenic. Running on ketones from animal fat (your stored fat)

  • Jennie Lyra says:

    Me and my husband lost a combined 230+ lbs doing fasting (not intermittent, days of fasting in a row). The euphoria is real. I have kept the lbs off for two years, only gaining some back because I am wanting to get pregnant. The best part is that my husband no longer snores!

  • Nick says:

    Your voice is so cool man!

  • matt wodziak says:

    The improved mood is partly due to stabilized blood sugar levels.

    Not to mention the improved mood and clarity observed by those on ketogenic diets. A diet that stabilizes blood sugar levels.

  • Phil Griffiths says:

    Good job promoting eating disorder behaviour

  • Michael McEvoy says:

    Motion graphics on point 👌

  • Besko says:

    Dont stop eating, think of the poor big corporations that wont get the trillions of dollars and the CEOs who wont be able to buy their 20th mansion and jet.

  • Simon Gütter says:

    Dont split up the video 🙁 🙁 🙁

  • Mark Biddy says:

    1966 seems to had been the year for fasting study conclusions. Great Work!!

  • TestingU 4Research says:

    You did not differentiate between types of fasting.

  • Rhimi Lee says:

    Fasting during certain times or all day with just water- what kind of fast?

  • amr khaled says:

    Finally translated to arabic

  • Ra Stev says:

    "We'll find out next" let's see what product is going to be pushed in the next episode. Book possibly? Just don't call it a "diet" book. 😉 sinical me. 😞 maybe he's just seeking new subscriber revenue 💸 💰.

  • Gaijin Coordinator says:

    Hope you're proud of killing all these people, greger.

  • Scott Gabelman says:

    People that are overweight don't fast to lose weight !

  • Johnny Walker says:

    fasting is a permanent lifestyle. not eating on Sundays isn't that hard. the biggest danger you need to watch out for is not getting enough salt during your fast, which is why most proponents of it will tell you to create an electrolyte mix that you drink to keep your body functioning properly.

  • Johnny Walker says:

    once you fast more than 24 hours, your body will start releasing growth hormone, which will repair all kinds of things in your body that it never gets a chance to because you're always shoveling food in your mouth

  • Raphael Quaglio says:

    Today I found an article proving the correlation between excess vitamin & minerals and weight gain.

  • I like Potatoes says:

    Lemme guess. If the water is vegan than it's alright but if it's not you'll die of a heart attack.

  • Parthipan Kamaleswaran says:

    to say that diets fail and people revert to previous body weight not only applies to intermittent fasting, but WFPBD as well. In my opinion, it is easier to convince someone to do a 16:8 fast than tell them to go on to a WFPBD. I understand the benefits of going vegan, but it's harder than the fasting regimens I get patients to do, at least to start their life choice on weight loss. Fasting should be done with guidance from your doctor, if suitable for you.

  • Jevster says:

    Greg doucette screaming right now

  • JadeMusic says:

    Come on, Dr. should know better than to call fasting a "starvation diet". 🙄 (Unless you were just mimicking what the research calls it?) Fasting is a centuries-old practice that induces autophagy, blunts appetite and burns fat naturally … allowing your body to use fat as an energy source. It's continuing to go without food when there aren't sufficient fat stores in the body that results in starvation. That's when it's taken too far and can result in death as the body breaks down muscle, organs and bone. Also, certain people shouldn't fast, which I'm sure you already know. But for the average healthy person, fasting from one day to five days (per Dr. Michael Klaper), is incredibly healthy for you..and beyond that, even..and intermittent fasting is just as good for those who just want to create some space between feedings, yet still attain fasting benefits. Most people seem ignorant when it comes to fasting, and I've rolled my eyes at those who state that skipping a meal means you're starving yourself. 😂 But we're so conditioned to eat at every opportunity, that it's little wonder that people fear hunger and don't understand what it means to fast. 🙁

  • TokyoElbow says:

    me me me me I I I

  • Clark Potter says:

    Day 9 of a water fast and feel great! Lots of energy and extremely clear mind.

    My longest fast is 21 days but starting a 22-day vegan challenge with my gf here, so just 10 this time.

    If you can fast 4 days, you can fast 40.

    It sounds hard but it's not at all. Ketosis is smooth sailing.

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