Starting an extended fasting regimen

(Paulene ) #1

Fast Facts
Female, 50yrs, 155cm tall (5’1)
No major health conditions (other than being obese)
Been on keto 4 months.
I’m in this for the weight loss.
Starting weight 105kg (231lb), now 95kg (209lb), Loss to date 10kg (22lb)

(Long history coming - skip to last paragraph for the gist of my post)

My weight has averaged about .25kg (.5lb) per week, which I feel is fairly slow and steady. At first, I found this rate of loss very disappointing but over time I have adjusted my expectations and am now sort-of OK with the pace. 4 months and 10kg in, I am starting to see a difference in my skin and I am quite concerned about excess and saggy skin. I know, I should wear that as a badge of honour. But I won’t. I know I’ll be really disappointed and discouraged if I finally end up slim but am still ashamed and embarrassed by my body. It’s not rational, but I know that is how I will feel. The saggy skin issue is why I am somewhat comfortable with the slower rate of loss.

I have been reading widely on how to avoid skin sag and the best solution I can come up with is extended fasting to achieve a state of autophagy. Hence, last week I overcame my fear of fasting and complete my first 3 day (72hr) fast, supplemented with fat at about 200g/day. It was supposed to be a 4 day fast, Sun night to Thurs night but I chickened out on the very first day, and started on Tuesday instead.

I found my first fast much easier than I anticipated so decided to try a 5-day water fast this week – no fat supplementation. My last meal was Sunday night and my next meal will be breakfast Saturday morning (I get home from work late on Fridays and don’t want to eat late at night, so I’m holding off for a nice breakfast). I have been very surprised to find that I have no hunger – I’m guessing this is because my body has LOTS of fat and protein (spare skin) to feast on so I don’t need to eat.
I have been slack measuring Ketones and BGL, but the measures yesterday were Ketone 4.4, BGL 3.9, which gives a GKI 0.89.

5 day fasts really fit well with my present lifestyle. I live away from home during the week and stay in B&Bs or share houses – so no pantry or fridge to raid, and no meal prep to do. SO (to get to the point) I’m thinking of making a 5-day fast a more regular thing.

I’m thinking of introducing either a regular Mon-Fri water fast followed by Sat & Sun feasting OR doing a Mon-Fri fast on a fortnightly basis and back to my usual OMAD or TMAD for the other days. Given my goal of reaching autophagy to reduce skin sag, I don’t really see the benefit of shorter, more frequent fasts.
I’d be interested to hear from people that have incorporated 5-day fasts into their eating pattern. What was your regimen? What results did you achieve? How did it effect weight loss? Any random side effects?

(Susan) #2

The longest I have done is 91 hours so I am no expert for the longer fasting, but I will be following you and wishing you the best =).

(Windmill Tilter) #3

No you shouldn’t wear it as a badge of honor. Let’s face it, even those of us metabolic disorders find as much motivation in the aesthetic benefits of fat loss as the health benefits. Loose skin is not a badge of honor, it’s a negative consequence of a less than optimal fat loss strategy. Ask anyone who claims their loose skin is a badge of honor if they wish it was gone. People don’t pay plastic surgeons $25,000 to surgically remove badges of honor. They do it because they don’t like how it looks, and they are self conscious about it.

Longer is not necessarily better when it comes to fasting for weight loss. If you plan to fast frequently over the long time horizon necessary for fat loss, shorter fasts make sense. Dr. Fung suggests three 48hr fasts a week, or on 72hr fast a week for long term weight loss. There are lot of reasons why this makes sense, and why these 2 strategies have been the most effective for hundreds of clients at Fung’s IDM clinic.

Because even ADF is effective for removing loose skin during fast loss, and it’s dramatically more sustainable over the long time horizon required. Because shorter fasts are easier to schedule life around. Because you don’t know what % of lean mass loss is muscle loss. Because metabolic adaptations occur as a consequence of frequent extended fasting. Because every published study of extended fasting has been done on subjects fasting for the first time, and literally no one understands how metabolisms change when someone does extended fasting frequently. Because you might find out after your 6th five-day fast that you are no longer capable of fasting (fasting burnout). I could go on but you get the point. Listen to Fung.

I was in your shoes last year trying to design a fasting regimen. I opted for doing 84Fast/60Feast on a continuous basis. I did it for about 4 months. I lost a lot 45lbs with no appreciable loose skin, then I took the rest of the year off to let my metabolism recover. I hit the wall in my ability to fast. This year I’m doing 60Fast/40Feast for a few months to drop down to goal weight.

Yup. By the end of a few months, fasting started to get really hard to do. My lasts fasts had a weird brain fog by day 3 that I didn’t like. I bought an indirect calorimeter to measure my RMR daily. My metabolism adapted to fasting such that my resting metabolic rate started having massive 250kcal/day swings downward when fasting was initiated, and jumped 250kcal when I resumed eating. Nothing like it has never been reported in the literature because every extended fasting study ever published was on people fasting for the first time. Others who were doing continuous feast/fast and who owned indirect calorimeters have had similar patterns of wild swings in RMR from feast to fast. It’s not necessarily a bad thing, and on average my RMR was slightly above normal even after 45lbs of fat loss in 4 months, but nobody knows how it happens or what it means. Frequent extended fasting is a complete black box scientifically.

Here is the chart that Fung put in his book to support his claim that RMR does not drop during a 4 day fast. It was of subjects fasting for the first time. The second chart is my RMR through a few feast/fast cycles. Spot the difference? Fung used the term RMR or metabolic rate over 100 times in the Obesity Code. Ever seen Fung’s data on the RMR’s of his clients who do continuous feast/fast? Me neither. Fung’s recommendation of three 48hr fasts per week, or one 72hr per week is probably not arbitrary, and it’s probably prudent to listen to him.

Having said all that, I know people who have done a 5 day per week fasting regimen. Some of them were successful and some burned out. It can absolutely be done. Nobody knows what the long term metabolic consequences or benefits of doing it are though. If you’re ok with those risks, I say go for it. I But there are risks, so I’m just doing laying out the reasons why shorter can make sense. I’m sorry if the massive wall of text above came off as preachy; it’s really just a brain dump. I’m obviously not an expert and I’m clearly not following Fung’s advice myself. I’m flying a bit closer to the sun, but I’ve found that I really enjoy feast/fast for a few months at a time and it gets results.

P.S. If you’re going to do extended fasting frequently, try to get into the gym to lift some heavy weights once per week to minimize muscle loss. The book “Body by Science” by Dr. McGuff sits on my night stand next to Dr. Fung’s “The Obesity Code”. It’s a 20 minute workout with just 5 exercises, it’s only done once per week, and the results are phenomenal.

(Paulene ) #4

Thanks for your response @Don_Q, that’s the sort of stuff I’m after.

I have watched lots of Fung videos and listened to podcast but have not heard him recommend a specific protocol. The last video I watched was The Power of 7 Day Fast on DietDoctor. BUT I haven’t read his book(s) so it’s probably time to go shopping.

I 've also searched far and wide for this sort of information but not found it. What is the source for this?

Do you have excess skin and is this protocol working to reduce saggy skin? And are you similar to me in age? I believe age is a big factor in skin sag.

I did ask for advice and experiences so I appreciate your contribution and candor.

(Windmill Tilter) #5

When I was a client of the IDM clinic last spring, these were the two recommended long term protocols. Maybe a current client can comment.

I forget where Dr. Fung says this explicitly. I think it was in an interview on Diet Doctor but I’m not sure. He says that he’s never had to refer a patient from the IDM clinic for skin surgery. Some of those folks are losing hundreds of pounds.

I’ll be 42 next month. As far as I can tell I don’t really have any at all. I’m only down about 50lbs from my peak weight of 275 though, and I think it becomes more apparent the skinnier you get. It’s possible I’ll have some by the time I’m 175.

(Atlanta Girl) #6

Hi Paulene,
Something you may want to incorporate on your non-fasting days is collagen. As we get older, our collagen diminishes, which in itself contributes to sagging skin. I use a collagen powder 2x a day on non-fasting days and incorporate homemade bone broth as my schedule permits. I have been using both for about 18months and I do see a difference - nails first at about 3mos, then hair and skin. People complimenting me out of the blue how great my skin looked at I haven’t adjusted the skincare regime. It certainly cannot hurt to add that to your arsenal considering your concerns. :slight_smile:

(Paulene ) #7

Hi @Atlanta_Girl - welcome to the forum. Thanks for the collagen suggestion. I just made my first batch of chicken bone broth for the collagen benfit. I’m hoping I’ll come to like the taste of it soon. :smirk:
How do you take your powder?

(Atlanta Girl) #8

I use Vital Proteins - I add it to my organic unsweetened green tea, I don’t taste anything. Collagen powder will have more collagen than the bone broth (make sure to add chicken feet!). I learned to roast a lemon with the bones before making the broth (rather than ACV)… And add in that garlic and spices… I also save the fat I scoop off for cooking.


I used to do 5-7 day fasts monthly, there was a couple times I’d take a week off then do another. At first I’d loose decent weight but this was based on WEIGHT, I wasn’t measuring BF% at that time. After months of doing that it had diminishing results. I definitely lost muscle and slowed my metabolism (which was tested). Really not a huge fan of long fasts anymore. I think all the real benefits can more or less be had doing a PSMF and at least then you’re still eating and giving your metabolism something to do.

(Atlanta Girl) #10

I have been doing 96-112 hour fasts every week since December (except a 2 week break). Note, my primary goal is not weight loss - it has been more of a body reset (chronic insomnia, joint pain, fatigue).

I start my fast Wednesdays after my OMAD about 10am. Wrap it up Sunday or Monday. I change things up depending on how I feel and just seeing how my body reacts.

1 cup of black coffee in the am with pinch of pink salt. Organic green tea/water the rest of the day. I have Magnesium & Potassium & Vitamin D daily. (I have MS, so my D levels low.) Multivitamin every other day. Fung has said green tea and the supplements ok.

Weight loss was all over the place. Some weeks 8lbs, some 12lbs, some no loss. Ironically, I was less active the weeks I lost 12lbs. And far more active the weeks loss was minimum.

After 2nd round of fasting, I was sleeping 8+ hours a night multiple nights in a row, feel better energy and pain-wise, and focus. When I stopped for 2wks and went back to regular super-clean Keto, the insomnia came back.

I found when I exceed 96hours, I wasn’t hungry. I didn’t have “fantasies” of what my meal back would be. I was kinda “meh” about it. I could easily keep going, but I am part of a program that donates plasma for research, and I need to make sure my protein levels are in ranges. I think I will still do a 12 day fast with Lent. But, as always, I listen to my body.

(Paulene ) #11

Thanks for sharing your experience, @lfod14.


If we were built on an assembly line with parts from the same bin, we could authoritatively make standard recommendations to one another. There wouldn’t be many ways, there would be just THE WAY to do things.

Rule #1: You are an N of 1 trial. No one can tell you what’s best for you.

Recommendations and research are 100% controversial. Meaning nothing is settled. No MD, Ph.D., health guru, confident forum expert, YouTube health advisor, …or me, can give you instructions that are right for YOU.

With all of that said and out of the way here is what I’ve done, that works for me. I have bounced between LCHF and keto for a little over 2 decades (started with Adkins back then) Almost 10 years ago I started using eating windows. I don’t consider this fasting, but many do. I simply skipped breakfast and lunch and ate dinner. Then I went with the 5:2 method, where I’d fast 2 roughly 36 hour periods twice a week usually separated by at least one day. Then a few years ago I started doing a long-term fast of 5-9 days perodically. There really wasn’t any regiment to it. Now I do quarterly 7-9 day water fast (I do drink black coffee too). But my main objective is to enter a GKI of 1 for a few days.

Now, why do I do this kind of fasting? Primarily because of family history with chronic diseases, and some suspected genetic risk markers.

I suggest you get some baseline bloodwork done and perhaps order a complete workup quarterly at first to track long-term trends. I order a full workup twice per year now. I’d also recommend that you set up a regiment of tracking both your blood ketones (BHB) and glucose and calculating your GKI. I do mine twice per day, in the morning and evening. But starting you may want to add a midday reading to the mix. At the same time monitor and track blood pressure and heart rate. This is to get a feel for your own metabolism and biomarkers.

Pay attention to any significant adverse symptoms. Although, I’ve never had any. Fasting for me now is easy. I don’t get much physical hunger anymore. On a scale of 1-5 with 5 feeling like I’d eat grass to survive, and 1 being no feeling of hunger, most of my long term fast are spent at 1 with maybe passing short-term periods of 2s and 3s during the first 24-48 hours. But most of that is psychological hunger, not true physical hunger. After day three I’m usually on cruise control at that point. I don’t feel empty, I don’t feel physical hunger, I have a family who eats, and I have food always available, with no desire to eat. Occasionally I’ll even make dinner for my kids or wife while I’m fasting.
That’s my second objective, which is psychological discipline, mind over the body if you will. But that’s just a personal objective of mine.

Take everything I’ve said with a grain of salt because that’s what it’s worth. You are an N of 1 trial and will have to find your own way.

(Paulene ) #13

Thanks for your advice and suggestions, @Ehamil42.

I’m delaying extended fasting until I have my keto rash under control. I believe fasting made it significantly worse.

I don’t think I’ve actually been hungry since I started keto 5 months ago, even with IF/OMAD and the few EFs I have done. Sure, I get a desire to eat, but I don’t think it’s hunger.


A lot of times people think they’re hungry is because for some stupid evolutionary reason, humans have a very weak thirst instinct. When we need water the signal is very weak, so a lot of people walk around in a perpetual state of dehydrated. Another nasty aspect of this weak thirst instinct is that often it’s misinterpret by a brain as hunger.

But in western cultures we don’t know what real physical hunger actually is anymore. It’s mostly the idea of skipping a meal is bad combined with wanting the sensual pleasure of taste and the dopamine rush eating gives our brain. Most of what we experience is psychological and conditioned hunger. We convince ourselves we need to eat.

With 70% of the US population overweight or obese, this is obviously not the case. People are not physically hungry.

(Bob M) #15

Shoot, 6+ years low carb/keto, and I still get hungry. I’m hungry right now, while trying to fast for 36 hours for the first time in forever.

If I wasn’t trying to fast, I’d eat.

(Paulene ) #16

Hey @ctviggen, I’ll trade some of your hunger for some of my keto rash! :smile: Deal??

(Katie) #17

I actually found this thread searching for the 5 fast/2feast routine! At the beginning of the year I started carnivore and while it was amazing at curbing my appetite, and making my cravings diminish completely, my weightloss success with it was nonexistent. So this last sunday night I started my first 5 day fast, and I’ve got to say it’s been so much easier than all the other times I’ve fasted. I have steady energy, my muscles aren’t sore and fatigued like they were before…
I plan on breaking my fast Friday night and through the weekend with carnivore foods only. I have to think that eating carnivore has really made the food obsession go away that always plagued me before.
Maybe we can cheer eachother on in upcoming fasts!

(back and doublin' down) #18

That’s exactly why I love this thread! Congrats on your fasting. I’m on my 3rd day of my first 5 day fast, planning to break on Saturday morning sometime.

(Katie) #19

Hooray!! Good for you! Are you taking electrolytes or just going straight water? I hear so many conflicting things, so I decided to take half of what the snake diet is calling for, and then if muscle cramps or fatigue set in I might adjust.
Do you have any plans for your 2 days refeed? I was thinking omad, possibly 2mad but only carnivore as to hopefully make next week of fasting that much easier

(Paulene ) #20

That’s really interesting @Kaliko81 (and disappointing for you, I’m sure). Maybe you are one of those people for whom meat is insulinogenic.

What are your thoughts on a 5 fast / 2 feast routine?