What is the longest fast that you've completed?

(Newimprovedme ) #1

What is the longest fast that you’ve completed? How and why did you break the fast.

Ten years ago before finding keto I had all kinds of digestive issue…which caused energy, focus and weight issues. I did some research on water fasting and found out that it could be used to reset the digestive system. I was desperate so I decided to do a 5 day fast. The first 3 days were the toughest. By the time I got to day 5, I was no longer hungry so I aimed for 10 days. At day 10 I decided to keep going until I could no longer go. Day 23 was that day. The fast really helped me gain control of my digestive system. Unfortunately, I went back to my SAD diet…but my system has never been as bad as before the fast.

A one hundred day fast

I’m curious about longer fasts. Dr. Phinney seems to think they may do more harm than good, even potentially deadly.

(Guardian of the bacon) #3

90 hours has been my longest. That was my goal when I began it. It was leading up to an employee Christmas party. It was in part a preemptive strike against a likely overindulgence of (keto friendly) food. I did stay keto clean and I certainly did overindulge on prime rib, crab legs, and shrimp.

I think a monthly 3-4 day fast is probably in my future with routine 18-6 or 20-4 IF. I may contemplate an annual 7-10 day fast for the autophagic effects.


I’ve been able to get to 7 days twice with some added fat. (I’m not carrying enough extra fuel around any more). I must say the most pleasant days were 4 and 5. I thought I go on forever. Last fast I tapped out at 3 days. I think I need to do them less often now.

(bulkbiker) #5

I have done 2 7-day fasts over the past three months. First was with my equivalent BPC (cream and coconut oil), second was more water based with some broth (canned consomme rather than home made I’m afraid). Had significant weight loss with both fasts but most of it has come back on partly due to xmas I fear. May do another next week leading up to my next HbA1c and holiday. Will again try to do mainly water and black coffee (yuk).

(G. Andrew Duthie) #6

Currently on day 5 of an extended fast, with supplemental fat, which I believe is my longest. At around 108 hours, if my math is correct.

I’m probably going to break it today or tomorrow. Will try to ease in, as I’ve made the mistake of eating more than I should at the end of previous extended fasts, which usually leads to some discomfort.


I got to 33 days. My hard stop was set at 40 days. But, was willing to go as far as my body accepted that I should go.

I only had water, coffee and tea. Broth only once per week, and multivitamin twice per week.

At the 32 day mark, during the evening, I remembered feeling hungry. It was unusual, because I really didn’t feel hungry for pretty much the entire fast (except day 3…which I found challenging…I felt very hungry). On day 33, I broke my fast with a small spinach salad. Waited about an hour and then had bacon and eggs, with HWC in my coffee…and then the next day, I did not eat. I was not hungry. My next meal was 48 hours later. I’m now eating once per 24 hours within a 1 hour feeding window.

I’m very glad I did it. My digestive system is in much better shape. I feel better now.


I did a 28 day fast one time long ago. I did it based on a fasting book that said pretty much everyone had enough fat to support a 28 day fast. Lost a lot of weight, sadly, gained it all back, this was way before my recent keto days.

(Steak and iron) #9

fasting for a few months is probably deadly.


Why? That’s a pretty blanket statement.

It really depends on the person and how much fat they have to sustain themselves.

(Steak and iron) #11

I said possibly. If I did it or you did it, we’d die.

(bulkbiker) #12

err you said probably… rather different to possibly…

(Steak and iron) #13

So I did. My mistake.

(G. Andrew Duthie) #14

Depends on how much fat you are carrying. If you have little body fat, then yeah, fasting for months probably isn’t in the cards. But I’m guessing that doesn’t apply to the vast majority of folks here.

(Pye) #15

Fasting for a few months is a hunger strike! :fearful:


IDK, at this point I’m frustrated I’ve consider not eating for a several months at least to kick start weight loss and let my body heal itself without having to process food or other chemicals for a while.

(Genevieve Biggs) #17

I have done 7 days twice, before Keto. I would like to try it again now after being fat adapted.

(James storie) #18

Well, I regularly only eat once a day. I just completed a 7 day fast. I only broke it because 7 days was the plan. I really don’t know what hunger feels line anymore!

(Pye) #19

I was saying tongue in cheek.

I hope you take a step back and make sure you look at all info on the keto way and you’ll then be better to make a choice. But don’t make it out of frustration if you can help it.


I really like what @pye is saying.

@Pilotbob, a strategy that worked for me is building up to a long fast regimen. First did a 24hour, then 48 hour, then 4 days, then one week, and then longer. Got myself up to 33 days.

I understand your frustration, as I too was one of those with trouble losing on keto WOE alone.

Go slow…step up the fasting duration…and you will learn lots and gain so much more control on your body’s dynamics. I sincerely hope the best for you.