I started doing keto about 3 years ago to help control IBS. I started at 20g carbs for the first month. I had the keto flu (tired, not feeling well, etc.), but it didn’t pass after the first week. That whole first month I felt awful: lethargic, foggy, and I was chronically short of breath, which wasn’t a symptom I saw listed anywhere. So, after that month, I increased my carb intake to closer to 40g per day and I felt a lot better. At the time I theorized it was because I didn’t have much of my own fat to burn (I’m naturally “underweight” by arbitrary norms) and so assumed I just needed more carbs than other people in order to function. I was still in mild ketosis but felt energetic, etc. I would still get short of breath when exercising, so I started making an electrolyte drink and having that before I exercised and that helped a lot.
Fast forward about a year: I found myself being less and less strict about my diet. I was still eating low-carb, but not exactly keto. My IBS worsened a bit, but not enough to make me feel I needed to stay in ketosis all the time. This is where I stay for about another year.
Then, last fall, I started getting back into running. I’m training to run a 5K with my teenager who runs track. I kept being short of breath when running. Then as the weeks/ months went by, I started being short of breath just normally through the day. I even started waking up at night feeling like I couldn’t get enough air. I remembered that electrolyte drink I used to make and started drinking that again. It definitely helped a lot but didn’t solve the problem entirely.
Now I want to get back into ketosis to improve my strength and stamina for running. Every time I try to get below 50g carbs/day I find myself not being able to breathe well frequently. But interestingly, I can now breathe better when I am running than when I’m at rest. I don’t know what to make of that unless it is related to BP.
I keep scouring online info about ketosis and I can’t find anything about shortness of breath being a common symptom. Has anyone else experienced this, and if so, what was the cause? How did you deal with it? I’ll be seeing my GP in August for bloodwork and I hope I get some sort of answer and I hope I don’t have to see a cardiologist or pulmonary doctor. We’ll see.
Can keto cause shortness of breath?
Shortness of breath during fasting
I don’t know if this is the same thing, but I used to get something called air hunger. I wasn’t really short of breath, but I would feel like I couldn’t get a deep enough breath. I felt like I had to work extra hard to get enough air into my lungs by deliberately taking an extra deep breath.
I learned about something called histamine intolerance and it turns out I was eating a lot of histamine containing foods. Other symptoms included a stuffed nose every night and an eye that watered for seemingly no reason. Anyway, when I reduced the amount of histamine in my diet, the air hunger, watering eye, and stuffed nose went away. In fact, my sense of smell greatly improved.
I don’t know if air hunger is what you have, but if that seems like an apt description, you may want to look into histamine intolerance.
I had the following a decade ago when I was eating feedlot meat and vegetables. Mostly chicken. Nobody would think I had atherosclerosis by how thin I was but I had it from the junk meat. Couldn’t run because I would run out of breath.
Ya know what’s interesting? I tried buying grass fed beef from two different farms in my area. I’m guessing, I don’t know for sure, that grass fed beef may be hung longer than feedlot meat due to the fact it is leaner than the feedlot meat.
I had a lot of histamine trouble from the grass fed meat. My nose would stuff up and I would get really itchy after eating it. That doesn’t happen to me from the beef I buy from the grocery store.
It’s called PH balance your blood is becoming more acidic (very hard to breath) rather than it’s usual alkaline when your running because your probably making a lot ketones your not really using for fuel yet because your not fat adapted which takes around 6 months or 27 weeks to become truly ketogenically adapted.
You really need to breath deeper or learning how to breath differently before you run; like Wim Hof who can climb in altitudes (mountain sickness) that require oxygen and he does not?
That’s why I like using a CPAP machine when sleeping because it enhances your energy levels (more like astronomically) during waking hours relative to atmospheric pressure so you can move your body mass much faster relative to prior oxygenation input.
Right now I’m really interested in experimenting with inflatable hyperbaric chambers.
“Air hunger” does sound more like what I’m experiencing rather than shortness of breath. I just hadn’t heard that term before. But, yes, it is like I can’t get a deep enough breath to feel satisfied. And I am frequently congested. Thanks for the tip! I’ll look this up. 
It has been so long since I was diagnosed with asthma that I no longer recall the diagnostic criteria, but I do remember that I presented with an unexplained cough and significant allergies. I had scratched myself with my shirt off while waiting for the doctor, and he noticed the resulting welts (a sign of allergies) as soon as he opened the door of the examination room. Combining that with the cough, he finished making his diagnosis before fully entering the room.
You might consider getting tested for allergies or asthma. I had assumed that my growing shortness of breath was a natural consequence of getting older and fatter, but once the inhalers started working, it became clear that my lungs just needed help. (This was in spite of the fact that, even with my bronchi at their worst, I still had more lung capacity than most people. The problem was that I wasn’t getting enough air for me, even though it might have been enough for someone else.)
I have found over the years since that my need for nasal and pulmonary inhalers waxes and wanes with environmental influences. Right now, after three years of a ketogenic diet, I find that I am doing well on just a daily dose of antihistamine.
So get checked out. There might be something they can do to help, and you might be amazed.
Thanks, Paul! I will ask my doctor about that when I go in, in August. I know I’ve developed some allergies as I’ve gotten older that I didn’t used to have.
I too am going through the same and would like to know if you are better and what helped?
Hey Troy,
So the reason I haven’t updated this is because the story is very long and the answer regarding the link between keto and shortness of breath isn’t definative. It is interesting to me to hear that you are experiencing the same thing because there just doesn’t seem to be info on it.
When you increase your carbs does the breathing get easier? It did for me, but it didn’t solve the problem entirely.
Like I said the story and all the factors would be very long to tell so I’ll summarize the best I can. I went to my primary care doctor who did a full blood panel and other lab tests, all of which came back normal. He referred me to a cardiologist, who so far hadn’t found a problem. She had me do a 48 hour halter monitor and an echocardiogram, both of which were normal. I still have a treadmill test scheduled for October. She was the only one who had a suggestion for why I might be more short of breath while in ketosis. Her theory was that the process of muscle cells using ketones for energy requires more oxygen than the process of them using glucose for energy and That would explain why it would be harder when exercising especially. That was the only theory anyone has had so far for why being in ketosis originally triggered this issue for me and why it is worse the closer I get to ketosis. But I have no idea if this is actually the reason.
I’ve also seen an allergist who did a bunch of allergy skin prick tests to see it could be an allergic reaction but everything came back negative. She did a pulmonary test on me and determined that something is constricting my ability to inhale. Through testing she was able to eliminate asthma (whew!) And diagnosed me with laryngeal disfunction. Basically my larynx tightens on the inhale (when it should be relaxing) and constricts my air flow. It looks a lot like asthma, seems to happen at random, and exercise is a common trigger. I asked her about the “antihistamine intolerance” someone had suggested on my original post and she said it wasn’t worth persuing yet in my case. In my own I eliminated a lot of high histamine and histamine triggering foods and there didn’t seem to be a connection for me.
Anyway, she referred me to a speech therapist because there are breathing techniques and exercises that can help with laryngeal dysfunction. So I did that and, low and behold, it helped enormously.
But this still leaves me totally baffled regarding how ketosis plays in. What could that have to do with laryngeal dysfunction (aka vocal cord dysfunction or VCD)? VCD can also be triggered by reflux and the allergist (based on things I told her about swallowing problems I have) thinks I may have silent reflux. My breathing is almost always worse after I eat too so that would hold true for a connection. Another trigger for VCD can be stress, and being in ketosis can be a big stress on the body. And high fat goods are common reflux triggers. So that is my theory so far-- the bodily stress combined with lots of fat and subsequent reflux were triggering the VCD and making it hard for me to breathe.
Anyway, now I’m seeing a GI doctor to see if I have reflux and about my IBS (which is why I got on a keto diet to begin with). Those tests are still to come, so I don’t have insight there yet.
I have increased my carbs by quite a bit recently because being in ketosis makes me lose weight and I’m already under weight. So I’m also wondering if that stress on my body is a contributing factor. It is hard to say because my breathing has gotten better since I’ve gained a few pounds but that happened at the same time as learning the breathing exercises. So I don’t know if the weight mattered or not. I’m trying to balance gaining some weight with not eting the carbs (or carb amounts) that trigger my IBS. It is a constantly tricky line. Both the allergist and the GI doctor want me to get on a low FODMAP diet and see how that goes for IBS. It will certainly not be low carb and that concerns me because one if the fantastic side effects I wasn’t even looking for when I got on a low carb diet was mood and energy stabilization. I really hope the low FODMAP diet doesn’t screw that up. Anyway, I still have a bunch of tests to come and VCD is the only diagnosis or explanation so far. And like I said, how that would have anything to do with ketosis is entirely guess work on my part.
What are the details of your breathing issue?
Considering how many people eat high fat on this board, and few report reflux, I doubt this is true. For me, eating meat never causes this.
I have another thought for you. You mentioned that your electrolyte drink helped. Magnesium is an electrolyte and it helps muscles to relax. Could a magnesium deficiency be manifesting as tightening of your larynx?
Magnesium deficiency doesn’t necessarily show up in blood tests. I was having heart palpitations, but a blood test showed my Mg levels were fine. I upped my Mg intake substantially, from 400 mg a day to 800 mg a day and the palpitations went away. It took almost a month. So, even though the blood test showed my levels were fine, I really was deficient. My cardiologist did not figure it out. I did.
A great book to read is The Magnesium Miracle by Carolyn Dean, MD. I don’t remember all the symptoms of magnesium deficiency, but a quick scan through of the symptoms included acid reflux and breathing problems. It might be something to consider.
Hi, I had magnesium suggested to me by my chiropractor and I do take it regularly. As far as I can tell it doesn’t affect my breathing though. It does seem to help my IBS as long as I take just the right amount. A little too much and it has the opposite effect! LOL!
Thanks for the tip 
I get this if I’m very dehydrated sometimes, or caffeine withdrawal.
Thank you Karen for the succinct response. WOW!, who would have thought VCD could be a contributing factor? I have experience shortness of breath on and off, however, this time I am not able to get rid of it. I have tried to eliminate a lot of things thinking it may be related to allergies etc, but I cant seem to find a connection to that either. I am going to do VCD exercises to see how that goes - are there any particular ones that worked for you that you could sharep to get me started? Again, many thanks for the help.
Karen, what type of magnesium are you taking? Magnesium Oxide doesn’t absorb well and mostly causes diarra. Mag glycinate is good.
The main breathing exercise the therapist gave me goes like this: when you are feeling short of breath you do 3-5 sets of these:
exhale while making the letter “s” sound, like a snake hissing for a count of 3-5
inhale like you are sucking air through a straw (so very pursed lips) for a count of 3-5
When you’re already feeling short of breath, this is hard to do because your impulse is to keep trying to suck in enough air and this exercise further restricts your air, but it forces relaxation in the larynx. So, make yourself do it 3-5 times before trying to take a deep breath. Once you’ve completed the sets, breathe from your belly, not your chest. Imagine pulling air down to your belly button or lower back.
And when you’re not feeling short of breath, practice the belly breaths so that they become more natural. The more someone with VCD breathes like that normally, the less often they are likely to become short of breath to begin with.
Regarding allergies, the allergist I saw said that it would be highly unusual to have a food or environmental allergy that only manifests as random shortness of breath. She said that with true allergies, there are usually other symptoms with the breath like a rash or congestion or headaches. So since I don’t have any of that (and the allergy tests came back negative), it was further indication that it probably wasn’t a specific food or true environmental allergy. That made me happy because it meant I could expand what I was eating rather than continuing to restrict things more and more.
Oh, and I also wanted to say that I used to just get it on and off too (after that very first initial onset when I first did keto). It would be somewhat rare or would only be when exercising or if I drank alcohol. But this past spring it started happening more and more until it was a daily and sometimes constant issue. About a month ago I took myself to the ER because I couldn’t breathe. (this was before the VCD diagnosis.) I think the ER doc thought I was having a panic attack, and once again, all the tests came back normal. It was so frustrating.
This is great info to keep in mind. Thanks!
Stands true for me because this spring is when it started again for me and instead of a 1-2 week stint as in prior years, it has hung around constantly. This begs the question whether it is something in the air? Or just a co-incidence? But in life there are no co-incidences, right?
Having said that, I also am eliminating histamine containing foods as I have been drinking kefir and kombucha thinking they are health foods…lol. Love sauerkraut but have always had a reaction of breathlessness after eating it, so am kind of connecting the dots… Your post has been so useful, thank you so very much, Karen!