At what fat % is it unhealthy to do EFs?

(Van Huynh) #1

Hello fellow Fasters, (sorry for the lengthy text but…) I am attempting an EF, duration is for as long as the body feels good. My worry and question is, is EF beneficial for me: male, 167cm tall (or short), 67kg and not much fat but a little around the belly?
Background: I do OMAD regularly, 4-5 days a week and have done one 5.5 days EF and several 3 days EF’s. Also lift weights and do sprints. For the past 4 years I have continually researched and am still learning how to apply an ancestral way of living (n=1). I see improvements (body composition, eye sight returning to 20-20 vision) and enjoy the benefits of this life style but what’s bugging me is, can I conduct EFs with minimal fuel (fat) and for what duration? To what extend can one push the envelope?

Thanks you in advance for any guidance or for pointing in the right direction. — feeling thankful.

(Erin Macfarland ) #2

You will probably get a lot of different answers here, as some people strongly believe in extended fasting even when very lean. They will tell you that many lean people fast for extended periods (more than a day or two) regularly, but I would advise that just because you can doesn’t mean you should. If you are lean, say under 15% BF for a man, and want to fast for longer periods, I’d highly recommend supplementing with fat, as the body can only supply a certain amount of energy from stored body fat per day (there is a blog post about this if you search for it, about why fasting is easier for some people, written by @richard) I think forcing yourself to do extended fasts when lean can be deleterious mentally and physically. Having longer term goals in mind when it comes to keto is more important than forcing your body to do five day water fasts. Focusing on keeping insulin levels low and the other health benefits of keto will be more sustainable than trying to do long fasts on a regular basis. When I was a very low body fat percentage (under ten percent which is actually dangerous for a woman) I didn’t understand why I couldn’t seem to fast for longer than 24 hours. Well, it was because my body could not supply enough energy for me to meet basic needs. So don’t force your self to engage in longer fasts because you think they are somehow superior to shorter fasts while on keto. If you are lean and metabolically healthy there is no need to engage in fasts lasting longer than a day or two. But I might get some criticism from the hardcore fasting advocates here. But that is my experience and I think respecting your body and having long term goals is more important than trying to fast when it might not be appropriate.

(Richard Morris) #3

My Body fat is 19% and I’m almost at the point where I can’t extended fast and do any cardio - which is a bit of a shame cos I used to love fasted cycling.

(Erin Macfarland ) #4

That is amazing @richard!! Congratulations!

(Mark Rhodes) #5

I am at 15.9% at 203lbs. I lift three times a week and have a physically demanding job ( mechanical engineer in a manufacturing facility). My goal is ultimately 9.4% so I can say I am single digit BF ( when rounding :laughing:). When fasting for benefits other than fat loss I do a strict fast consisting of water and black coffee.
I use this formula. 203 x 15.9 = 32.9 lbs of available energy in fat pounds. 32.9 x 31 ( per pound) = 1000.58. For most of my fasts my RMR can adjust to use 1000 quite effectively without fat supplementation and while I have no evidence it seems plausible that other calorie needs could be met by some of the aminos freed during autophagy. Ultimately I have as of yet any ill effects on any EF 5-8 days in duration.

(Adam Kirby) #6

Wow man, that’s impressive!

(Ethan) #7

Do you lose energy or feel cruddy overall? I am curious what the symptoms are of not having access to body fat.

(Richard Morris) #8

I feel a little meh when exercising (that’s my metabolism slowing) and then afterwards when I get into the steam of a hot shower and in an enclosed space I smell a distinct odour of methane (that’s my body recruiting lean tissue for energy).

When I was 110 kgs at Ketofest in July, I was able to generate 2052 kCal/day from body fat so I could wake up and go cycle for 2 hours no worries.

Now at 100 kgs, I have 2/3rds of the body fat, so I can only generate around 1359 kCal/day.

Thanks Erin but at a BMI of 31, I am still obese I. The problem is my legs were built for a 150kg man who cycles up hills. Going keto drew down my body fat for energy but didn’t scale down my lean mass.

Just to show where I am at on a chart of humans with body fat % against BMI

White is women, Black is men, and red is me. I wonder if those other 2 outliers next to me went keto too.

image
image.png489×541 80.2 KB

I am just very dense now for a human :slight_smile:

(Ethan) #9

@richard, I totally understand the large legs thing. The first time I lost weight in my later teens, I was able to still leg press 1400 lbs despite weighing in at a very fit 175 lbs and bench pressing only 180 lbs.

(Adam Kirby) #10

Nice graph there, I am also denser than the average for my BMI. Although for me I’ve almost been the opposite of Richard, very skinny in my youth so I never built up any kind of lean mass to carry myself around. Putting on muscle has been a slow process for me.

(Van Huynh) #11

Thanks for the advice. My long term is 4X extended fasts a year, one each season. Combined with OMAD. The goal is to get as close to ancestral living as possible. This will have to also apply to reducing
my current 9-5, 5 days a week working in an office. But that’s for another post. Anyway I’m thinking the body is designed to not only survive but remain optimal even during periods of unsuccessful hunts, regardless of the fat percentage. In my last EF, apart from being cautious and monitoring of my body’s reaction I experienced something I can’t explain: 3rd night I started to think about killing something, a small animal like a chicken, a wallaby or a rat and putting it over open fire. This thought carried through into my sleep and dreams which became more and more interrupted over the 4th and 5th night. Rambling again. This spiritual thingy best for anothe post.
So, Will the pancreas / insulin respond to fat supplements?
I’m at 36hrs, sleep was great, woke naturally to light at dawn, walked the dog, don’t feel hungry, weight is steady, black coffee, have energy, head feels like it’s humming, pink H salt under tongue. At work and feeling normal… for now. Weights scheduled for lunch.
Will update as I fast. Will end if the body doesn’t feel right.
Anymore thoughts from anyone else is also appreciated.

(Michele) #12

The brain is certainly an interesting organ/instrument. I’ve just returned home from a week long abstract painting workshop. While sleeping, lucid dreaming and during the semi awake stage I have been “painting” not sure what but it has been both interesting and at times annoying as I would like some peace!