Fasting on carnivore makes my stomach shut down


I am in it not for weight loss but for autoimmune stuff. And while it makes a lot of things better, it doesn’t seem to solve some issues completely for me (after about 6 months). I am not done experimenting.

For reasons I will go into when I am done with my experiments (not yet), I want to lose some kilos temporarily. Now, I already have a healthy weight and doing OMAD or 2MAD I can keep my weight steady (doesn’t seem to make a difference). When I try to go for 48 hours without food, I just get cold. Which is normal. Sometimes hunger comes up and then it goes again. No problem.

But when I reintroduce food, I can’t eat much of it and I get heartburn for days. Apparently my stomach forgets how to produce acid. Since from an evolutionary perspective not having anything to eat for 48 hours occurred frequently, I don’t get what’s wrong here.

Any ideas how I can handle that? Currently I am trying OMAD and eating less calories every second day. But this is going really slow.

(Bacon is a many-splendoured thing) #2

Everyone is different. The Dudes’ two rules are (1) show us the science; and (2) figure out what works for you. You may be one of those people for whom fasting is not a good idea. Listen to your body.

(Geoffrey) #3

What food do you reintroduce with?
I ask because I’ve heard of some people not doing well by just jumping back into eating their regular meal.
I saw a video of Dr. Berry explaining that when he ends a fast he just has a scrambled egg because it’s easier on the stomach.

(KM) #4

I had the same experience. Coming close to carnivore in my day to day, then a 5 day fast. I was looking forward to how great food tastes when you break a fast, but the refeed of egg drop soup (an egg swirled in bone broth) left me a bit nauseous. Steak later on. Midnight woke up felt like I had stomach acid in my sinuses, heartburn was so bad.

Honestly I don’t remember how I was breaking fasts when doing more veg, but never had that experience before. Interested to hear how this all comes out.

(Ulia) #5

I only break fast with eggs and butter. Always work great. And I can also have some ACV.


I start eating steak until it doesn’t taste good after a fast. I might try to start with some eggs instead.

(Bob M) #7

I’ve found that starting slow is better. So, an egg or something small at first, then wait a bit (say 1 hour), then a larger meal.

As for heartburn, I can’t help there. I only get heartburn when I eat high carb.

(Bacon is a many-splendoured thing) #8

A lot of long-term carnivores find it unnecessary to fast. How important is fasting to you?

I doubt what’s going on is that your stomach “forgets how to produce acid.” It probably has more to do with the type of food you’re refeeding with. That would be my guess, anyway. I’d start by experimenting with either more or less fat than you are currently refeeding with, to see what kind of difference it makes. Or try some of the other suggestions in this thread.

Also, the quantity of food in that first meat might be relevant. Try eating less, followed by a later meal.


As I said, this is a temporary thing and I have a specific goal of going a few kilos below what I think is my optimal weight which I already have. Fasting is the only way I can see that happen. Long term I don’t really care about fasting.

I’ll try to reduce the amount of fat and food next time I refeed. And I’ll try eggs. Maybe the rare meat I eat is really too much for my stomach.

(Bacon is a many-splendoured thing) #10

It’s entirely possible. Use the eggs to get your stomach going again, then have the rare meat an hour or two later.

(Bob M) #11

I might also just be the amount. Start small. Of course, if you like eggs, an egg would be a great way to start. High in pretty much everything and not many calories.

I’m looking again at fasting, because if I eat, I get hungry. There are MANY times when I’m not hungry at all or only very mildly hungry at dinner, which is when the family sits down to eat. Sometimes, I can eat less than normal. But most times what happens is that I’ll eat, even a small amount, then I’ll get hungry, and I’ll end up eating more. Most times, it’s a full meal. Sometimes, it’s not.

But since I’m the type of person where eating CAUSES me to get hungry, I think a 36 hour fast every week isn’t a bad idea. Especially because I’m actually not that hungry the day after the 36 hour fast. Not sure why.


Heartburn can be due to too little acid in the stomach. Are you eating enough quality salt? It’s key for our body to make hydrochloric acid.
When I break my fast, now I can eat pretty much anything. However, this is a recent phenomenon in my ketovore / carnivore journey.


While fasting I sprinkle some salt into my water and I also drink some electrolytes which contain sodium. Might not be enough salt but when I take too much I get diarrhea.

My food is well salted though.


The opposite was also true. Feasting. If you are already at a healthy weight, why are you fasting every day?

No, it is not normal to be cold. It means your resting energy expenditure is going down. Try to eat sufficiently on eating days and consider fasting less often. Do not starve yourself. If this continues, go see your doctor.


I wanted to go into this in another thread when I am done with the experiment but ok:
This is my second carnivore attempt. First one worked phenomenal regarding autoimmune issues. Now it doesn’t work well. I did some things different this time. Last time I only ate lamb which made me nauseous quite quickly due to the amount of fat and this resulted in severe undereating and a quick loss of weight. This time it doesn’t work but since I eat other animal based food other than lamb I can eat enough. So what I am trying to reproduce is the weight loss. That’s the experiment.

This is absolutely common while fasting. Most people experience that after one day or two. You can read about that anywhere you try to read up on fasting. When eating a “normal” diet it was the same. And otherwise I feel well.


Dr. Jason Fung states basically the same. That it is not normal to be cold when fasting.


Do you happen to have a link? I’d like to hear more about that.


It would be on his Deitdoctor web site.

(Bacon is a many-splendoured thing) #19

Actually, his site is now called