Yesterday I tried to fast for just one day, though in the morning I had half a cup of coffee and late afternoon some butter, but my body became increasingly tired and sluggish, my legs getting that super heavy feeling, and I crashed into bed by the time I’d put my boys to bed, exhausted. I did eat pink himalayan rock salt throughout yesterday to keep up my electrolytes. This morning I woke up feeling exhausted, until I had two cups of coffee, the caffeine boost helped immensely, and I ate my first meal in the late morning/early afternoon as usual, consisting of 5 eggs. Felt infinitely better. It seems on my WOE, carnivore/ketowore which consists now of 100% grassfed beef, lamb muscle meat and organ meat, grassfed butter and grassfed raw milk, and occasionally some fish, my body can’t fast. If I even attempt it, my body starts to become ill, shut down. I wonder why this is? Possibly it’s because of my Tamoxifen, which leeches my energy anyway. But have any of you experienced you can’t fast? And what were your tricks for getting through that? Perhaps it is to do with level of stored body fat? I am slim and have not much body fat, possibly this is the reason why I can’t fast. But I just find it so curious as fasting, 24-48 hours is meant to be so healthy, a kind of reset for the gut. I certainly wouldn’t attempt extended fasts at this point. My body wouldn’t let me. Do any of you fast and how do you do it? For how long?
I can't fast
I intermittent fast, I can manage up to 22 hours, drinking unsweetened tea or plan water. I believe in a clean fast meaning no artificial sweeteners or heavy cream, just plan water and unsweetened unflavored tea and water.
It took me a few months to build myself up from 14 hours to my standard of 19 hours now.
I don’t have an answer, however, I’m wondering if you are fat adapted yet. I think fasting is much easier when you are. Also, what is your objective in fasting?
For me when I started, I was able to do a 24-hour water fast once a week. I was fat adapted and did that for several months. I found that although I could do it without issue, I just didn’t like it. Not eating made me unsettled and anxious feeling. Not going to do that to myself anymore, so I stopped.
If your goal is insulin regulation, I think you don’t have to worry if you eat when you are hungry or need refueling and refrain when you don’t. Your body knows how to regulate itself when you feed it properly and consistently (IMO).
I look forward to what others say on the topic.
I’d guess it’s some combination of your lean body (little body fat means less available fuel to draw upon) and your Tamoxifen Rx.
But I wouldn’t worry about whether you can or cannot comfortably refrain from eating for extended periods of time.
Fasting should be within one’s reasonable comfort range. Otherwise your body is telling you something important and you need to listen.
I’m not talking about folks with eating disorders of one type or another. But when you really listen to your body (not just rely on an occasionally growling stomach - which isn’t necessarily about hunger), you get essential n=1 information that’s typically actionable.
(BTW, putting two boys to bed is exhausting under any conditions. Kudos for getting this far on any day 
)
To answer your question above, I haven’t eaten “breakfast” in years. My first meal is typically sometime early afternoon (mostly protein - eggs, meat, cheese) and then dinner 4-5 hours later.
I guess this is what some refer to as intermittent fasting or a limited eating “window.” For me (a LMHR) it’s just what eating feels like.
I guess I could skip more meals, but I don’t see any reason to bother or try. I enjoy eating. Absent a compelling (health?) reason to engage in extended fasting, I’m not currently feeling the urge. YMMV.
Then don’t fast. I have even a lot of extra fat and I can’t fast at all. I could do it on high-carb (it was even automatic sometimes), it was hard but doable on keto but on carnivore? Nope, it doesn’t happen. I am stubborn so I will push eventually (well not against my body, that is impossible) but it’s quite fine not to fast, it’s not for everyone.
Hi Joey, I’ve never actually attempted to fast before, I was thinking I’d try to fast in the weekend as a reset for my gut. But I only got through one day, and realise now, this is not where my body wants to go. It is quite happy with two meals in a day, a typical day now looks like 4 eggs, some liver for the first meal and patties/burgers which I make myself for the second meal. My body feels no hunger between those two meals, even if I have my first late morning/early afternoon and the last in the evening. And when I fasted yesterday I wasn’t hungry, but my body felt tired and sluggish. My energy level is never that good anyway because of the Tamoxifen. But I noticed the difference for sure, my body definitely doesn’t want me to fast. I so agree about listening to the body. It is so smart. It got me used to the taste of liver in the space of two days even though initially I was put off by the sweet taste, and now I like it. My hunger/satiety signals are mild, a gentle nudge, so I do believe I am fat adapted, but fasting would definitely lower my energy levels too much, whereas when I keep to my two daily meals, it is happy.
Hi Marianne, I don’t think it’s to do with not being fat-adapted. I’m pretty sure my body is fat-adapted as (1) there is nothing that brings my body a greater sense of satiety than eating fat and (2) I eat two meals in a day, one in the late morning/early afternoon, which consists of some liver and 4 eggs, and one meal in the evening, which consists of my own homemade burgers/patties, no other ingredient than meat and salt. I do enjoy a coffee in the morning and one in the afternoon and pour in some of my raw grassfed milk. I also enjoy eating a few lumps of my grassfed butter. I don’t think it is likely that with this kind of WOE and having been eating this way for months, my body wouldn’t have reached fat-adaptation. And considering I have been slimming down from already lean, I see it even less likely. It may be it’s because of my Tamoxifen, as it leeches my energy, and when I fasted, my energy levels got even lower. I think this is one of those individual things, fasting, that it works for some people, but not everyone.
“I can’t fast”: That’s not surprising. I’ve seen the pictures you posted, and you’re very lean. You don’t have enough of a reserve to fast easily. If you really feel you must be fasting, a bit of butter or heavy cream in your coffee will probably be enough to get through the day. Just avoid eating so many calories that it stops being a fast. Dr. Fung’s Web site discusses this and gives a recommended limit for the amount of fat.
Hi Shinita, I agree, it’s not for everyone. I’d run out of meat and I just didn’t fancy fish, so I thought I’d fast. I actually started fasting the day before yesterday (Saturday), I’d forgotten, after that first meal of liver and eggs, I was so full after that meal. So I fasted the rest of the day, and thought I could get my meats at the butcher yesterday (Easter Sunday) and it was closed. So I thought that was a good opportunity to fast, as I’d never attempted it before. So yesterday, apart from eating a few lumps of my KerryGold butter and drinking half a cup of coffee I fasted. This morning I woke up insanely tired, but after two cups of coffee I was half back to myself. The butcher was open today so I’m sorted with meat for the week. I was ravenous by the time I was home, which was around earlyish afternoon, and ate 5 eggs. Have not felt hunger since. I think I won’t attempt fasting again, but I was curious how many on the forum can successfully fast.
Hi Paul, I actually did this instinctively, I ate lumps of butter and it brought me satiety. I also drank coffee. I have replaced grassfed raw milk with cream, so I put that in my coffee these days, as cream and conventional, pasteurised dairy in general doesn’t agree with me. So I wasn’t hungry when I fasted, but my energy levels crashed. I did eat pink himalayan rock salt throughout the day as well and drank sufficient water, drinking to thirst. I was thinking of fasting as a way to reset my gut, but my body doesn’t seem to want anything to do with fasting, that is fine, it was something I’d thought I’d try as I had read about the benefits from this, but I accept it’s not for everyone, though I am curious how it works for most. I am familiar with Dr. Jason Fung and I think his ideas are great and has helped a lot of people. I already do IF with my two meals a day, a late morning/early afternoon meal, and one evening meal, as this happens automatically I think on a ketogenic WOE that one feels less hungry because of the lower insulin. I currently don’t see a benefit for my body in attempting extended fasts, after attempting just a full day and failing, or not failing but having my body turn fasting down. At the moment I’m more interested in diving into Professor Ben Bikman’s work than that of Dr. Jason Fung, regarding insulin and metabolism. I’m deeply fascinated with Bikman’s teachings.
As Yogi Berra once remarked, when his teammates were commenting on the poor turnout for a game, “If they don’t want to come, nobody can stop them.”
I take great pleasure in the equivalent thought, that if I don’t want to fast, nobody can stop me.
Tamoxifen alone can cause excessive tiredness. Combine that with a relatively low amount of bodyfat and I’d say the stage is set for more of a struggle with fasting. If you last ate in the evening, then by the next afternoon you’re in that 14 to 24 hour period where the stomach has emptied, and the small intestine is mostly empty. Lots of people have a tough time around the 18 hour mark. The “pipeline is mostly empty” at this point, and it’s the ‘post-absorptive phase’ that Dr. Fung talks about. Blood sugar is declining - and in your case it sure sounds like you’re feeling it. Eating ketogenically - I’m not sure what one’s ketone and fatty acid levels do after most of a day without eating; would be interesting to see what happens.
“Ravenous” - that’s a pretty good signal there. 
I’ve felt tired sometimes when fasting, like really dragging, and there have been times when caffeine really made a big difference. Not always, and true bigtime hunger wasn’t there, either way.
Eating fat to prolong a ‘fast’ versus just going back to eating regularly - I think there’s a lot to be said for it. Protein and carbs make the biggest difference, by far, going from the fasting state to eating. More fat from outside may mean a litte less from inside (one’s fat stores) but if it makes an energy difference, if one feels better that way, then little is lost, if any - the hormonal response and the net effect on the body isn’t much different from eating nothing.
I can relate, nice idea in theory, especially for me with my big fatty belly… But my body doesn’t work that way. It usually helps me to get ready for a fast mentally, I used to spend a few days to make my brain ready, my determination serious enough… That was on normal keto. It doesn’t work anymore but maybe one day… Increased autophagy sounds good but I have other reasons as well. But I am in no hurry. I do it when I can, I just stay open and not being a slave of eating, no matter if I need it or not, that’s a good idea anyway…
If you want a fast but can’t do a proper one, try what Paul said, eat fat. You can do it unlike me 
The next thing is fat fast, lots of fat and almost no protein helps with satiation, at least it did to me and many others. But it’s a not a fast, of course. But maybe it has some benefits. I tried it once or twice out of curiosity, it was interesting to see how differently my body behaves if I have those very odd macros.
Hi Shinita, I did eat a few lumps of butter and drank half a cup of coffee and got by on that as in, felt plenty satiated, no hunger, but energy levels were much too low. My energy levels are normally low anyway due to Tamoxifen, but I no longer crash, which is what, among other things, this wonderful WOE, carnivore or ketowore, as I eat in addition to animal flesh eggs and dairy, has given me, a steady energy even if it’s not as good a level of energy as I would have liked. I think I had an idea, I certainly entertained the thought that if I managed to fast over the weekends it would be a nice way to reset my system/gut and experience benefits of autophagy to boot. But I think with my Tamoxifen it is not achievable. My hope is, and it burns fervently within me, to, with the help of this ketowore WOE, quit Tamoxifen in 3 years from now, I have been on it about 2 years. So that would be 5 in total. I believe in the body’s ability to heal, provided it’s given the right building blocks.
Hi Doug, I think you’re right, that it could be a combination of Tamoxifen and being lean that caused my energy levels to drop so much when I attempted a fast. I wasn’t hungry, but felt weak. It wasn’t a good feeling. I’d actually been fasting since the early afternoon of this Saturday that was, through Easter Sunday that was yesterday, and only ate my first meal early-ish afternoon today, and then I properly felt hunger, and the eggs were absolutely delicious. My body thanked me heartily. I think it’s possibly also harder for people on carnivore/ketowore to fast because of not consuming carbs, I could be wrong. My body is happy with just the two meals, but those two meals it has to have for my energy levels to be sufficient, and for me to function throughout the day. If I ever attempted a fast again, I would have to keep myself dosed up on caffeine, and then it might just work, but as I was thinking of a fast as a reset for the system/gut, I think the amount of caffeine I’d require might cancel any benefits.
There is another reason to fast, it is great for weight maintenance. And it can be a great way to also lose weight.
Hi MattWisti, I only attempted a fast because (1) I had run out of my grassfed meats from the butcher and (2) I didn’t fancy the canned fish in my cupboard. So I thought I’d attempt a fast having never attempted it before. I also thought it might be a nice reset for the gut. I didn’t feel hunger on the fast, but my energy levels got too low. I already do IF in the sense that I generally have my last meal at 17:00pm, or 18:00pm, and then don’t have my first meal next day typically until 11:00am, sometimes 12:00am. And my body is very happy with this, and my two meals. I drink coffee in the morning though, and have a little of my raw grassfed milk in it, it makes a nice, energising treat, and I consider this my breakfast.
For me as long as I am busy doing something and not having time to think about it I don’t have any issues fasting. I am sure I have about 25 pounds of excess fat that I could stand to burn off, well that is what my doctor’s head nurse says, but all she is doing is looking at the BMI charts. I am weighing what I weighed my 8 years of military service and I can wear my dress uniform which isn’t tight at all. My Intermittent fasting is mostly for maintaining my weight loss and hopefully to aid in slimming down some more. I am happy with my weight, but my waist and belly could be a few inches slimmer.
That is key for me, too. If I’m busy I can go several days with no issues. If all I’m doing all day is listening to my fat cells complain, it’s a heck of a long day.
I have no idea what it means. Why would we need to reset out gut and what reset means…? My body just tends to work as intended…
And I didn’t bring in your super leanness this far as even without fat to lose, many can do a short EF though not all and IDK how they function anyway, I am fat and even I can’t get enough energy per day from my fat reserves according to the info I have read… But it’s not THAT a big deal for me to fast, I just would need forced to it as I eat when I get hungry or weak a bit, even without real problems (well hunger let alone weakness is a big problem for me 
but my body would function well enough for a long while. it just loves its temper tantrums when I don’t feed it). So the body handles things somehow beyond the formulas - but when there is no extra fat or very little, no wonder it gets hard…
By the way, do you have experience with somewhat shorter fasts? Like 20-24 hours? Skipping a day is way more than even that, I experienced the difference… I did 26 hour fasts moderately easily as I still can eat every day that way. A whole day and 2 nights are much more difficult and a whole weekend? That’s long. Even for me with all my fat reserves.