Intermittent Fasting vs 24-48 Hour Fasting - Benefits & Drawbacks 

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Stop apologising for nerding out on the research. It is literally the reason I listen to you over other RU-vid people.

I’m 60 years old. Former all natural bodybuilding champion ( 30 years ago) but have always worked out and have been a 16-8, 18,6 faster. I have just started incorporating longer term fasting into my regimen and I love it. I’ve only done it twice so far , first time was 36 hour snd today I’m finishing a 48 hour fast. The cognitive benefits I get is huge snd very noticeable to me. I plan on doing a 48 hour fast now once a month along with my 16-8, and 18-6 routine. I watch everything you put out there and find your video some of the best. Thank you for your work.

It's magic...I eat once a day...and throw in at least a couple of 48 to 72 hr fast per month....I'm going broke buying new cloths weekly but I love it!!

I started doing 24 hours fasting 4 months ago, then up to 36 couple months after that. I do some light workout here and there and also cut off all unnecessary sugars like sweets and drinks. Lost 20 lbs so far. I think fasting does work, but cutting back sugar probably helps alot

I do a weekly 36 hour fast and OMAD on one of the later days in the week! Every month I push one of my 36 hour fast to a 48 hour fast!

I do a 36 hour fast every week. My doctor says he wishes all his patients had blood chemistry like mine.

I did IF for months straight last time. I lost weight very well. This time around, I am doing something different. 5 days during the work week, I do IF 16:8 and 2 meals a day, and on weekends, I eat 2 to 3 meals a day, and I am eating at or near my TDEE and lifting weights, and walking, but lightly, and plenty of rest days. I am losing weight slower, but as long as I am losing, I'll continue, and ratchet down slightly each time I need to. This is my 3rd round of Keto, and I'[m down over 100 lbs, yet I have yoyoed because of a surgery, where I had to quit Keto for several months, but I am still down that original 100lbs, I had lost even more pre surgery the 2nd time on keto, and was near my goal weight. But those months off low carb this time, caused almost 30 lbs weight gain. I'm down 12 lbs from that now eating the way I am with IF again. Basically, cutting the carbs, and IF, are the two biggest changes. I had about 8-9 lbs of water weight, the rest is this WOE. So, my sitting around for 5 months unable to do anything physical, turned me to mush and made me weak. (Spinal Fusion). I am just now getting back to where I was pre surgery physically. So Body recomp is going on, slowing weight loss as well. But, fat loss is on schedule. That is the important thing.

Yes Thomas. In reference to your last video about that article concerning the study about Keto. Keep doing what you do on your channel. You’re one of my favorites because you know what you’re talking about.

I’ve been water fasting 22/2 daily for 13 months, throwing in a 36-48 hour fast every 10 days or so. It’s been absolutely life changing for me. I love your videos & your obviously extremely well educated/researched, but sometimes I get very confused lol😵‍💫

Love that you emphasize the idea of flexibility with fasting. That's probably the reason I love it the most, it's completely different from any other 'diet' out there.

I've lost 4kg this week with 16 to 22hr fasts. My energy levels have been absolutely fantabulous and I've been studying really well too! I absolutely love it

I do 16/8 everyday, and once every 2 or 3 weeks, I'll throw in a random 24 to 36 hour fast when my body least expects it...haha it feels awesome 😂

I usually do 18:6 or 20:4 but I like to throw in a 24 or 26 hour fast occasionally. I am not overweight (anymore) and I love having all the free time to accomplish things other than planning and fixing meals.

I do 16-8 every Mon to Wed and then 20-4 every Thurs to Sun. Every couple of weeks I do a couple of 24 hour fast. Then every couple of months I do a 36 or 48 hour fast. Currently in my first 72 hour fast wish me luck! Thanks for the info as ever Thomas!

I feel 16:8 is easy but addictive and tiring if done everyday to alleviate PCOS. I like 24 twice a week or 48 hours once a month. So I have decided during my cycle I'll do one 48hours fast that week to help menorrhagia. It had helped before 98% of the time and now that I have learnt more so I am just going to implement everything I know and helps.

I don't know if I agree that a prolonged fast would lower metabolism "if you've already hit an IF plateau." Keeping the logic that it's a different mechanism, I think a 2+ day fast would help your metabolism normalize - provided your nutrition is on point when you break fast.

I love how I feel when I do 16:8 IF. Hunger gone, energy good, mental clarity great. Thank you for explaining this. You're great, Thomas!!!!

Thanks for your great content… after 15 years insulintherapy i lost 15 kg in 5 month with IF and LCHF/Keto… Hba1c 5,7 and no insulin needed..no fatty liver anymore.. Bodyfat down to 14%… Love the physiological stuff.. greetings from Germany and sorry for my poor english…

Currently on the 40th hour of a 5 day water fast. Feel great right now and I'm taking a once a day multivitamin.

I thought I’d share my story. I had trouble sleeping, tried cutting out screen time after 9 etc but I was still up at 1 am. Stopped eating after 2 pm and now I pass out around 9:30-10 pm. Trouble sleeping gone!

Fasting changed my life. Thank you! I do don't it everyday but definitely helps with self control

You, Dr Berg and Sten Ekberg have been tremendous help in this regard. Also Sadhguru ;).

I need to lose 15kgs. Started 36hr fast (basically skip all meals and go to sleep) yesterday and lost 1.3kg so far. Mainly water obviously but still motivating to see on the scales and the weirdest thing is that I don't feel that hungry yet today morning. I know that will come later but I might as well ride it as long as I can. God luck to everyone on their fasting journeys ! It's the only way that's ever worked for me. Not easy but nothing good ever is.

Personally for me, my body can only handle IF at the moment. It is very challenging to get past 20 hours, so I am happy with what I am currently doing, May be some day I will achieve a prolonged fast. For now I will appreciate the benefits IF is providing!

Thanks Tom! You’ve been a huge positive influence. So how long of a fast is considered a “prolonged fast”? I generally do 20 hour fasts every other day, and every other week I TRY to do a 36. I’m 52 years old and I’ve lost over 30 pounds and have about 10-15 to go…. Thanks!

I just do intermittent dry fasting everyday for 18 hours so I only drink and eat between 1pm to 7pm which works brilliantly. My mate does a dry fast for 36 hours once a week ( sunday 7pm-Tuesday 7am) and nothing else.

You better start writing an annual review paper and publish it😌😌😌

I’ve extended my fasting time based on how I feel. IF for a period of time, but when circumstances permit I go longer, begin to get deeper ketosis, more energy. Lately my longer fasts are after I’ve “cheated” and near a new moon. My results are great, although I know sometimes I’m not getting the protein, I’ve begun to focus on more protein.

When I hear prolonged fast.. I think weeks.. Not 24 hours.. I just did 19 days.. Feeling pretty good now..

Intermittent fasting PROFOUNDLY transformed my life in a very short time. I've been very sick for about 15 years.

I am so grateful for the information that Thomas shares with us! All these concerns/thoughts that were taking over my brain are always answered by him in tremendous details! What a treat!!! Thank you, Sir!!!

I was doing a probably 18/6 fast without really thinking about it. Just one meal in the evening and maybe snack late evening. Never eaten breakfast and often skipped lunch. I recently switched to 48hr (one meal every other day) to lose some weight and seems to be working great so far. One benefit I don't see mentioned is cost; You're essentially halving your food bill, which in my case has allowed me to eat higher quality fresher food on my eating days.

For weight loss, I've been doing OMAD most days of the week, trying to keep it Sub-1000cals, sometimes as low as 300cals. Saturday or Sunday I eat like... 1500cals, and that's a feed day. I've started doing 48 fasts at the beginning of the week, so Monday I might not eat at all, and then go back to OMAD sub-1000 on Tuesday. I've started trying to lean into Low Carb/Keto as well.

He is right I was doing 20-4 fasting for about one month during weekdays and managed to loose 15 pounds, I was very motivated so I continued for another month but only managed to loose 5 pounds then I did a 24 hour fast one friday aside from the 20-4 from monday to thursday after only one week of this I managed to loose another 5 pounds just in one week. It's crazy how this thing really works during my eating periods I don't watch what I eat i wouldn't say I eat unhealthy tho, I even eat some fast food sometimes but in general I tried to cook at home steak, beans, salmon shrimp. Aside from loosing weight you feel a-lot more energetic I even started hiking because you feel like somehow you need to burn off your energy, this is aside from playing soccer almost everyday. The days I don't do exercise I can't sleep that's the biggest side-effect I would say.

I have six meals a week. Monday to Friday and Sunday. 12-2pm. That’s it

I would've mixed the 2 had I not ran into this insightful video! Exactly what I need, thank you so much!

Lost 22kg in 3 months now... From 116 to 94

Hi Thomas, absolutely absolutely love your videos and thank you for the information, much appreciated!

Wow coming back and listening to this has really helped me

SO much helpful information. Turns out, I was confusing PF with IF (bad thinking: if some is good, more is better and more more is betterer! Oops.). I really needed this video ~ thank you Thomas!

Love your content!

I don't get how the metabolic rate can fluctuate! I mean, the number of calories that a certain activity needs is always the same and the number of calories that a stable muscle mass needs to keep its mass is also constant...

Love this guys videos best place to get advice and knowledge

Hey Thomas can you do a video about faecal transplants and their (either good or bad) potential for fixing gut issues? I see great results for C Diff infections and I’m wondering if other imbalances could be fixed as well. Thanks! Always love your videos.

I am not a fan of dieting be it calorie counting, intermittent fasting' keto, etc... Too many rules and too much to think about. I eat what I want all week long but, Sunday after dinner I just stop eating. Tuesday morning or early afternoon I start eating again. Usually works out to about 40 hours and I do that every week. Nothing to think about, plan or buy anything special. All you have to do is Not Eat it doesn't get easier than that! I've been doing this for quite a while and I feel great and my weight and health has been excellent and I'm 61, 6' 178 pounds with a 34 waist. My old weight most of my life was about 200 pounds. The funny thing is I feel my best on Tuesday mornings before breaking my fast. No hunger whatsoever with lots of energy and mental focus. Good luck and give it a try

Thanks for the video Thomas!

I'll reduce what's in my fridge down to steak, pasture raised organic eggs, avocados, grass fed butter, beef talo, ground beef, wild caught sardines in extra virgin olive oil, and organic cod liver oil and eat only these foods for 8 days. roughly 2,500-3,000 calories per day. then fast for 48 hours. Then get back into it. When the next 8 days are done then i do a 60-72 hr fast depending on the schedule and days it falls on. Then right back to it. I've lost 140lbs and feel absolutely amazing

Your science is always so in depth! Mostly things i cant find online

What do you know about ITP, I have contracted it since my Astrazeneca Covid Jab

This is exactly what I was looking for today.

I work 12 hour night shifts three times a week. Not a set schedule at all. I am curious about studies for weight loss and helping your sleep cycle for night shift workers.

As a 66 year old 2&1/2 days into a fast, I have had two nights of restless sleep, dull headache, dragging today in general, and I stink. Still I know the light in the tunnel is not a train.

I am an recovering herion addict since 2002. Sugar was my first addiction in life. Now its ketones. 16/8 with healthy keto and I feel a drug uphoria. . I don't want to come down from this high so I cut out my cheat days and also quit drinking. Ketones have to be a drug if I am skipping cheat days.

Yes Ramadan is a chance for a good intermediate fasting

Reading some of the comments with a cookie in my mouth… thinking if I put it down now I can start counting the hours of fasting but then I say naahh too early to stop eating, will try another day! 🤣😂

Amazing info, thanks thomas

Tom a problem you may have to ask your wife about, hair. Women know this and men don't, collagen and biotin makes your hair go from dry and brittle to soft and shining in 24hrs. I took predigested liquid collagen for hair and skin, and much to my delight it cured my tendonitis in 2 weeks. I thought I was old and had to live with it.

Dear Thomas, Thanks for all the great information. I have noticed that when I do a 36-38 hour fast, the next day after I eat I feel terrible. I am tired amd inflamed. I break my fast with a meal of vegitables, fish and eggs as this is easy to digest, no carbs. Any suggestions?

@3:30 Of course you are going to have a reduction in your basal metabolic rate if you restrict calories by 25% for several months BECAUSE YOU ARE LOSING WEIGHT!!!!!!!! Lower body mass will reduce your metabolic rate all other things being equal. During the "several months" you are restricting calories by 25%, you should lose well over 10% of body weight and therefore your metabolic rate will decrease. Since fat is not as metabolically active as lean mass, you will want to lose well over the 8%-10% you are losing in metabolic rate, but it WILL come down carrying less mass.

Can you possibly do a video if there are any affects with cannabis and fasting?🙏

Very interesting take on the immune system. Thanks for your information. Getting towards the end you mentioned " rebuild" immune system with prolonged fasting, you refer to it by 48 hours or does it have to be longer?? Thanks again

Thank you for all your advice 🙏🌟😊☀️☀️😊🌟🙏☀️😊🌟🙏

But if you're burning your own fat, does that count as part of your caloric intake?

12:45 Dr Jason Fung has a different view of fasting effect on the immune system, his focus is on the Insulin/Leptin reductions allowing the Immune system to function much more efficiently.

long fasts I believe just begin at hour 72 and go up from there,....to 4,5, 10,20 days. 24 hour is still IF. and 48 is intermediate.

Outstanding. Than you

I have been on IF for months but didn’t lose much because I’m still having carbs. So what u eat does affect the result.

Very valuable info. Thanks Thomas! I feel like I'm right on track!

Great stuff!

So this is me.... Llsing weight with IF... Hitted a plateau... Extended my fasts more and more and did a lot of 36 and 48 hour fast... Barely ate and gained alot of my weight back. Just figured out that I ate barely 50% of my daily Kcal I need and this problably f*ed up my metabolism. Losing weight will be a struggle for a lifetime I'm afraid. I will take a 3 to 4 week break from IF, eat 7 meals a day and count my calories... From 1700kcal a day to 3.000kcal a day. I exercise 4 times a week. Will begin with IF again after 4 weeks I think... But will count my calories on the fasting days trying to not f*up my metabolism again.

3:12 I disagree. I’ve been doing IF going on 4 years now, maintaining the same weight without counting calories. I just focus on protein and avoid processed foods and sugar.

I’m confused with the metabolic rate talk. Since IF like OMAD is making the body to burn fat, caloric reduction due to lesser quantity of food intake should not affect metabolic for people what have lots of stored fats that do IF for weight loss. Dr Jason Fong also mentioned the same. It should be perfectly fine to switch IF OMAD and prolonged 48 or 72 fast since fats are fueling the body despite reduction of calorie intake. My understanding is wrong?🤔😶

Zero issues eating 3-4K calorie a day in an 8 hour window haha

The issue I’m having is I really don’t know what’s a calorie deficit for myself anymore. I feel like metabolism is all messed up and what I think is a deficit seems to be maintenance but I feel like it’s harder to cut even more and then probably have to cut even more! Any suggestions?

Im doing very fine with OMAD

Excellent close 👏🏻👍🏻

hey Thomas you didn't really tell us how many times we should do a prolonged fast per week/month, and what about the people working out a lot?

I do both intermittent and long term fast to help with seizures,allergies and migraines. I was having trouble sleeping day 4 of my recent 7day fast and my husband gave me melatonin gummy vitamins. Without thinking about it I took them. I feel like I ruined the fast even the calories were super low. 😫

I do 36 hour clean fasts x2-3 times a week for over a month...I haven't dropped a single pound.

Dr. Don Lyman says a fast is over 24 hours. Everything else is time restricted feeding. I like to call my 16/8 fast a fast because it makes me sound cooler. Lol

How long does it take to reset a slow metabolism and how does one recover from prolonged calorie restriction poor diet?

Is it better ( or not!) to try a prolonged fast on a Strength training day vs cardio day vs rest day? Btw, really appreciate all your content, thank you 🙏🏽

Wait! You sped off with a confusing conclusion that Prolonged Fasting is recharging and sort of out to lunch; but what about the autophagy? I do a weekly 36 hour fast (sleep-day-sleep) for autophagy and weight loss; the rest of the week I am sliding from keto to paleo.

Overall which is better, day on/day off fasting with keto or 20:4 intermittent fasting 5 days a week with keto?

I love love u program but can I have coffee with prolong fasting? I have serious head ale when I don’t have coffee, help

I’ve been following your plan and I definitely see the difference as well as weight loss, BUT I’m going on night shift soon and idk what to do?? Please help!!!

If possible make a vedio to reduce ldl level in keto diet should I try mediterranean keto diet pls suggest me

Does taking Duromine diet pill (phentermine) break a fast?

Im doing ver fine with OMAF

David Sinclair said that reducing your calorie intake will extend your life.

Thomas, how do you approach prolonged fasting (24 hours plus) if you're an athlete? I train at least 3 times per week but I sort of get intimidated I won't be able to function properly if I go say two days without eating. I don't think I saw a video of you explaining this for people who train regularly.

This is what a Monk told me once. The reason Monks dont eat after 12 noon is so they can sleep better, the Monk fast basically.

CAN YOU GIVE INFO , OR DO VIDEO ON HIW TO HELP YOUR BODY RECOVER FROM PROLONGED ORAL STEROID USE....MY TESTOSTERONE, AND CORTISOL LEVELS ARE ALL MESSED UP AND ITS GOING TO TAKE MONTHS FOR MY 48 YEAR OLD BODY TO RECOVER.

So you never mentioned what to do once you hit that plateau with IF. If I don’t start long fasts, do I eat 3 meals/ day again? And for how long before I try a long fast?

I am experiencing cognative issues. What is better 24 our 36hr or 48 hr fasting this is my first time. Last time I finished eating was Sunday night 7:30 pm I am now at about 37hrs

I do need aggressive weight loss... so im confused as to whether this is what i should do. There is a lot of conflictint and overwhelming information. Im doing both, i alternate between 16:8 and 23:1 ... With 2 weeks of ADF.... Following a 3:4 method (3 eat, 4 fast, with 2 of the fast days as 48 hours) Not sure why i do it this way but its just what has felt natural. Im doing it "mostly" tor weight loss- laot 30, wnd have 30 to go. But i also want to turn back aging, decrease insomnia, and jelp with migraines and autoimmunity. Im vegetarian and having a hard time getting enough protein. Im losing muscle mass quick. Would pescatarian be ok?

u r 🔥

I’ve been wondering . Let’s say you’re on keto , and then you cheat with a high carb meal or have some sugar. How long should I wait to eat a high fat meal again?

Sorry, but his info on intermittent v. Longer fast is incorrect. Listen to Dr. Jason Fung instead.