IBS and the keto diet


IBS and the keto diet

When Audra Atkins-Reeves started the low-carb keto diet in October 2016, her only aim was to lose weight — and happily she found within five months she had lost 40 lbs (18 kg).

The 36-year old IT supervisor in California, however, discovered another welcome, unexpected benefit from her new way of eating: it almost completely eliminated her long-standing irritable bowel syndrome. Within a month of starting the keto diet her gut was remarkably calm, quiet, and cooperative for the first time in decades.

“Honestly, I’d never had a normal bowel movement almost my whole life,” said Atkins-Reeves, who alternated between extreme constipation and diarrhea (called IBS-C and IBS-D). Her doctor’s solution was to give her drugs for both, which she switched between.

Changing to a low-carb, high-fat diet completely resolved her constipation and reduced her formerly frequent attacks of diarrhea to less than once a month.

“My ketogenic diet now completely controls my IBS symptoms,” she says, noting that it even seems to have healed her gut’s old problems. “If I do ever cheat and indulge in some of my old triggers like ice cream or fruit, it doesn’t seem to cause an attack any more. In the past I would have been in the bathroom within an hour.”

Most of us are ecstatic to broadcast our success with weight loss or reversal of type 2 diabetes on the keto diet. We talk to friends and family enthusiastically about the pounds melting off, our blood sugar normalizing, our cravings gone and our minds becoming beautifully clear. We post our before-and-after pictures on Facebook and detail how now eating meat, cheese, eggs and butter is giving us a new lease on life.

But go into rapturous details about keto’s impact on one’s bowels? Not so much! Talking frankly and honestly about gastrointestinal issues is squeamish stuff, the last taboo. It’s tough to share the particulars of how a once-churning caldron of GI distress has quelled or the bloated pain of constipation eased, all by switching to a very low-carbohydrate diet.


And yet, for many it is a welcome, surprising benefit. Improvements in IBS symptoms are commonly reported in emails to Diet Doctor. Many keto themed blogs discuss the phenomenon as do multiple Reddit discussion threads.

A survey of doctors on this site, who recommend low-carb/keto eating, found that among their patients, it is very common to have a dramatic improvement, even a resolution of long-standing IBS symptoms. It is one of the most welcome side effects of the diet. Dr. Ted Naiman said he has seen it occur among “countless patients.” Dr. Sarah Hallberg, too, says “we see it all the time.”

So has Dr. Andreas Eenfeldt: “I remember one male patient in his late 20s who had suffered crippling IBS symptoms for most of his life,” he said. “I suggested he try a low-carb and high-fat diet, gave him a one-page pamphlet, and he agreed to give it a try. It was a quick ten-minute consultation. When I called him two weeks later, his GI symptoms were not only completely gone, for the first time he could remember, he’d also lost a surprising amount of excess weight. And all without a single medication.”

Dr. Evelyne Bourdua-Roy agrees: “It is super common. Most patients have given up hopes of getting a treatment, it seems. They’ve tried a lot of stuff, they have had a colonoscopy, they have had tests for food intolerances and celiac disease with no answers.”

But when they go on the low-carb high-fat (LCHF) diet, most see an improvement within two weeks or less, she says. Not only does Dr. Bourdua-Roy’s have the majority of her patients on the diet report significant improvement or a complete disappearance of their IBS symptoms, she has experienced it herself. “I have had a complete resolution of bloating, pain and excessive gas.”

I have, too. I now consider my mild IBS completely cured on the ketogenic diet. In my very first post for Diet Doctor I described how going low carb resolved not only my pre-diabetes, but resulted in barely a grumble from my sometimes grumpy gut. Like Atkins-Reeves, too, it seems the diet has even reset my underlying intestinal tolerance. Trigger foods that used to bother me, like runny eggs or raw spinach, don’t anymore.

Could restricting carbohydrates be the key to your happier gut?

Read on for more information about what is known, and not known, about IBS in general and when carbohydrate restriction might be just the solution to tame your tumultuous tummy.


1. IBS is very common and very disruptive

At least 15 per cent of the general population are estimated to suffer from IBS — typically twice as many women as men. That means some 75 million people in Europe and 48 million in the US are affected. Studies show that more than one in ten visits to family doctors and at least one in four to gastroenterologists are for IBS symptoms. It is second only to colds for missed days at work.1

But do we talk about it a lot? Nope. Most suffer in silence and many don’t even bring it up to their doctor. Dr.Bourdua-Roy, says that silence is very common among her patients. “Most of my new patients don’t even mention it… they have tried numerous modifications to their diet so most think it is useless to make another effort.”

The key defining symptoms of IBS are recurrent abdominal bloating, pain, diarrhea and/or constipation. Excessive flatulence, cramping, heartburn, nausea, vomiting, exhaustion, sweating, shivering, anal itching, and sudden incontinence can be part of the not-so-pretty picture, too.2

A few serious medical conditions can have symptoms similar to IBS: celiac disease, inflammatory bowel disease (Crohn’s and ulcerative colitis), and certain types of cancer, especially colon or ovarian cancer in which new GI symptoms come on rapidly, especially at a later age. While all are much rarer than IBS, these conditions should be ruled out before settling on the IBS diagnosis, international IBS guidelines say.3

The key factor that distinguishes IBS from other gastrointestinal issues is that diagnostic tests can’t find anything wrong – that is why it is often called a “functional” disorder, meaning it is based on symptoms after other causes have been ruled out.4

The takeaway: If IBS is causing a lot of distress, especially if symptoms are new, do have a doctor rule out other more severe health issues first. But if IBS is the eventual diagnosis, you are not alone. And a low-carb high-fat diet could easily help.


2. Subtle physiologic differences now being found

For years, because nothing aberrant could be found on colonoscopies or other diagnostic tests, doctors dismissed IBS and offered little help to patients. That may be one main reason why so many people with the symptoms keep quiet about it.

In fact, for decades IBS symptoms were often seen by the medical profession as largely psychosomatic — all in one’s head — which often caused those who suffered to be labelled as neurotic or as having psychiatric precursors, particularly anxiety and depression. Chronic stress is known to contribute to, and worsen, the disease; and anxiety and depression are often natural responses to a condition that can cause fear of public embarrassment or undermine quality of life, — especially when the symptoms are dismissed as psychological by still too many doctors.5

Research, however, is now pointing to a variety of subtle changes that each may underlie the development of IBS, such as an altered immune system, the presence of low-grade inflammation, the proliferation of nerve fibres in the intestinal wall or pre-existing genetic susceptibility.6

The takeaway: While stress can make IBS worse, it is not all in your head; genetic susceptibility and micro-organic changes, hitherto undetected by diagnostic tests, are likely at play. If your doctor gives you the old “nervous temperament” explanation for your symptoms, find a new doctor – and try cutting carbs.


3. FODMAPs: research shows cutting out short chain carbohydrates improves symptoms


Foods containing FODMAPs

In recent years a specific diet developed in Australia, called the low FODMAP diet, has been getting a lot of research attention, with some studies showing 75 per cent of people with diagnosed IBS had their symptoms improve on it. FODMAP is an acronym for fermentable oligosaccharides, disaccharides, monosaccharide’s and polyols. That unwieldy name describes types of short chain carbohydrates found in many fruits, vegetables, legumes, grains, dairy products and some processed foods.7

FODMAPs are all carbs, and what they all have in common is that they tend to ferment in the small intestine, causing gas and bloating. They are also poorly absorbed by the gut wall and cause fluid to remain in the intestinal space, leading to diarrhea in those susceptible to IBS.

High FODMAPS include fructose and fructans found in many fruits, vegetables and wheat products; lactose, a sugar found in milk and some, but not all, dairy products; galactooligosaccharides (GOSs) found in beans and lentils; and sugar alcohols (polyols) such as the artificial sweeteners sorbitol, xylitol and mannitol.8

Eating a low FODMAP diet has in the last few years become the front line therapy for IBS, in which patients usually work with a dietitian to first eliminate all FODMAPs in their diet and then slowly reintroduce them, one-by-one back into their meals to see which they can tolerate and which they cannot.9

More than 200 FODMAP studies now exist, with the majority showing improved symptoms for more than 75% of patients. However, most IBS specialists still also recommend, alongside low FODMAPs, the traditional diet recommended for years, which stresses small meals, regular food intake and avoidance of coffee and fat.10

Many patient discussion threads on the low FODMAP diet, however, call it difficult to follow, rigid, and depressing to figure out the more than 200 carbs that are “in” or “out.”

Dr. Ted Naiman notes that the general very low-carb diet is easier. “No carbs equals no fermentation equals no IBS. It is simple and it works great.”

The takeaway: Ample evidence now exists that short-chain carbohydrates called FODMAPs can cause problems with people with IBS, but the intricacies of the diet are challenging. A low-carb diet is a simpler way to eliminate the common FODMAPs.


4. Research evidence for a very low-carbohydrate or ketogenic diet

In 2009 a US team at the University of North Carolina, that included Dr. Eric Westman, specifically examined a very low-carb diet — less than 20g of carbs a day — for IBS. During the study, 13 people with diarrhea-predominant IBS started with a standard American diet for two weeks, then switched to a very low-carb diet for four weeks; 10 out of the 13 subjects (77%) had significant improvements, with the very low-carb diet improving their abdominal pain, reducing their diarrhea and improving their quality of life.11

“A very low-carb diet, or LCHF, is basically a low FODMAP diet with even fewer carbs,” said Dr Westman.

Currently a randomized clinical trial is recruiting in Sweden that will assign patients to one of three diets for four weeks: standard diet, a low FODMAP diet, and a very low-carbohydrate diet.12

The takeaway: Anecdotal evidence abounds and low-carb physicians constantly see IBS symptom improvement; formal research evidence is growing. Most people, if they are going to have IBS improvements on a low-carb ketogenic diet, see it within two to four weeks.

“The fact is that you will know quickly whether this works for you,” says Dr. Bourdua-Roy. “Try it for two weeks; take the Diet Doctor challenge. You will get the answer!”

If you have experienced improvement in your IBS symptoms with the LCHF or ketogenic diet, let us know in the comments.

Anne Mullens


Top posts and guides about keto

  1. A ketogenic diet for beginners
  2. 14-day keto diet plan
  3. Keto for beginners – new video course!

More on digestive issues

There’s one digestive issue that sometimes does not improve on keto, it may occasionally even get worse: constipation. If needed, use our guide below.

More on digestive issues, how they can be improved and stories about success

Top posts by Anne Mullens

  • Top 10 tips to lose weight on low carb for women 40+
  • Reflections on humans held captive in a carbohydrate culture
  • Trying to conceive? Try the better baby diet of beef, butter & bacon

Top keto videos


  1. Current Gastroenterology Reports: Dietary fructose intolerance, fructan intolerance and FODMAPs

  2. Journal of Gastroenterology and Hepatology: The evidence base for efficacy of the low FODMAP diet in irritable bowel syndrome: is it ready for prime time as a first-line therapy?

  3. Gastroenterology: Diet low in FODMAPs reduces symptoms of irritable bowel syndrome as well as traditional dietary advice: a randomized controlled trial

  4. Clinical Gastroenterology and Hepatology: A very low-carbohydrate diet improves symptoms and quality of life in diarrhea-predominant irritable bowel syndrome

  5. Clinicaltrials.gov: A comparison of three different treatment options for irritable bowel syndrome (Car-IBS)


  1. Paula
    This has been my experience, too - and what a welcome relief! IBS can be a social and physical nightmare. It took me a solid 6-8 months to get my guts behaving properly. I'm not sure whether it was merely a change in my microbiome, the elimination of FODMAPs, or a combination thereof, but I'm deeply grateful. It is simply one more reason (and they're piling up!) to stay the course, and following LCHF for life.
  2. Jean
    IBS is just another way of saying "we don't know what's wrong with you". I wish instead of using this pseudo diagnosis, the medical profession would take more interest in looking at root causes. If doctors were willing to say "I don't know" more often perhaps more progress would be made in trying to figure things out. I have a long "ibs" story that appeared here on dietdoctor (along with my weight loss story.) I believe I had something which is known as MC, which does have a diagnostic criteria attached to the diagnosis but it is still a long way from being explanatory. I figured my issues out for myself finding the answers I was seeking through Dr Google and never hvaing the diagnostic test necessary for an official diagnosis. Doctors were of no help and when things got so severe that I was house bound I didn't even consider seeing a doctor since I had already gone that root and got nothing out of it except added expenses. Low carb, even low Fodmap, was not enough. I need an even more restrictive diet. I repeat. IBS is not a disease. It is merely a label. Dr Hyman says that naming something is not the same as understanding something. I agree.
  3. Ward
    After a necessary round of antibiotics I began to experience gut distress and, worst of all, sleep disturbance. Discussions with doctors provided no improvements. Suggestions included more antibiotics (no improvements - big surprise in retrospect) and a CPAP (again no improvements- while CPAP is a genuine issue, my impression with sleep docs is like the old aphorism: “when your only tool is a hammer, everything looks like a nail” - for the sleep docs the hammer is a CPAP). I learned about FODMAPS from Dr. Google and that did help but the problem of determining what to eliminate from my diet seemed close to an almost intractable problem. The solution for me was a draconian elimination of plants from my diet. Pharaphasing Dr. Ted Naiman above: no plants = no fermentation = no IBS AND much improved sleep. The seemingly recent discussion of the somewhat questionable role of plants in the human diet has made the plant-free very low carb diet seem sustainable in the long term ( see posts like those of Dr. Georgia Ede on the Diet Doctor site). Will I reintroduce plants to my diet? Perhaps, but at the moment I’m enjoying feeling great and sleeping (and my rib eyes and bacon).
  4. Jean
    Ward - I spent about 2 years eating almost no fiber. Fiber always made my symptoms worse even though that's the advice most traditional doctors will give you, "eat more fiber". I had doctors simply repeat that phrase to me even after I told them fiber made things worse. I then, without the help of the medical professsion, figured out the specific foods that I was sensitive to and eventually began to add back fiber in the form of leafy greens mostly plus some avocado and cruciferous vegetables.
  5. Lou Burke
    Before I found Keto. I found H202 therapy. This cured IBS and Candida.I would not have been able to do Beef on Keto way of eating without this healing. Joint pain gone and strength has returned. Now I have enjoyed Keto and loving the results of the the plan. Thanks for the great recipes.
  6. Stacy
    I've had IBS-d since childhood. It's pretty debilitating to plan your life around the availability and proximity of a bathroom. Ive researched
    LCHF/Keto diets and am a week in...just hoping for some relief
  7. Lucy
    I have or inherited from prescription meds over the years, IBS..D. Or it could be from pelvic radiation thirty years ago... although gastr. dr. said its healed. I wanted to say that I tried the FODMAP diet a year ago and followed it exactly for two weeks. It did not help and in fact several times I had projectile diarrhea. I am happy for those it works for. Now a Senior I take Imodium and have a bland diet.... this disease is a life changer... no more outings, visits to friends, healthy food... plus daily cramps sometimes for hours and have to lie diwn. Could not even travel to my brothers funeral.... could be worse but its bad enough.
  8. Barbara
    Lucy..... I could go on and on and on about my 18 month struggle with intractable diarrhea. Before leaving the house, I chew one - 3 Pepto Bismol lozenges. This was told to me by a friend who sees the same gastro people I do, who NEVER told me that one!!
    Try the Pepto ..... works for me ;)
  9. Carl
    I too have found a LCHF diet to have completely solved my 7 year bout of IBS-C. I had been trying to follow a low FODMAP diet but wasn't getting significant relief. In its defense, I likely wasn't doing a great job.
    The bloating and swelling had become so bad I developed diastasis recti and couldn't breathe while tying my shoes.

    Out of frustration I decided to try a low carb diet to see if loosing weight would help. Within a couple weeks my symptoms resolved and after a couple more weeks I'd lost 25lbs and two pant sizes.
    If you're suffering from IBS you should really try this. It's not complicated unless you make it so. Learn your simple heathy fat sources like avocados, replace starches and grains with cauliflower and greens, and increase your meat. Drink only water to start. Do it for two weeks and don't cheat. If a LCHF diet works for you share that fact. IBS is horrible and the treatments all close to worthless.

  10. Sam
    I am confused because my daughter of 16 has terrible IBS! I is interfering with her life to the point some days she can’t go out and not just a day or two but many in a row. However things like cauliflower, cream, avocado etc are high fodmap and she eats rice a lot because she can’t eat bread. If she does keto, she will no be able to eat rice and the things like cauliflower and avocado supposedly will upset her gut.
    If she tries keto, will it mean that she can tolerate cauliflower, avocado and cream etc etc because the carbs are so low? Or will I just make her sicker? If she can’t eat the cauliflower, rice and such she eats so little now already, how will she survive on an even stricter diet? Or will keto mean that she can eat those things like cauliflower without the same problems? Fodmap diet has helped but she is still struggling - it hasn’t been a cure and her life is still being controlled by “where the nearest toilet is.” Can anyone advise me? Doctors have been seriously no help at all.
    Replies: #11, #16
  11. Nicole
    Sam, I came to this website seeking info on keto for my own IBS-C and just got through reading your comment. I live with your frustration for my own Ibs every day and am at a loss. I feel like I’ve tried everything...it helps for a few weeks, maybe months, then out of no where it comes back. Has she seen a functional medicine doctor? Or just a regular MD? Functional doctors are more helpful I believe.
  12. Bex
    I suffered for 20+years--mostly in silence, with TERRIBLE IBS! I was tested for many ailments and tried every medicine recommended by doctors and NEVER found anything but temporary relief combating only the symptoms. Travel has always been a painful nightmare for me--and I had so many triggers, I was always crossing another food off my list, swearing to never eat it again as it resulted in horrific consequences. I am now nearly two weeks in Ketosis and I haven't had ONE single episode (yet)! I am shocked and ecstatic! If it weren't happening to me, I would never believe it. Not only that, but I am eating things like avocado, lettuce, and CREAM, which ordinarily would send me directly to the restroom. No pain, no bloat, no issues. I wish I knew WHY this works so well, but then, who am I to question such a wonderful blessing!
  13. Ellen
    I started having IBS symptoms after having CDIFF brought on by a round of clindamycin...I wasn't the same for 8 long years. I started the keto diet to help with inflammation in my body and had the pleasant surprise of having my IBS no longer be an issue. It is a difficult world when you cant go anywhere without knowing where the bathroom is...wondering if you will make it if you need to...if there will be a line. If you do have any close call it causes post traumatic stress. I am so grateful for Keto
  14. Dave
    I am 73 and I suffered from lifelong IBS until I went on a keto diet 2.5 years ago. Within two weeks my symptoms completely disappeared and have not returned. Quite apart from reversing T2 diabetes, which was my reason for adopting the diet, this has been a life changing "side effect"!
  15. Gillian
    I had my large bowel removed 42 years ago due to ulcerative colitis. About 2 years ago I developed frequent and pain especially on one side. Also nauseous and off sweet things and drank a lot. A year ago di agnosed with type 2 diabetes and started on LCHF straightaway. Noticed that the and pain and nausea went almost immediately. All ok ds of tests had shown nothing apart from a small hiatus hernia. I've now reduced my protein pump inhibitor and lost 4 stone
  16. Anne
    Hi Sam - I feel for you and your daughter. As the author of the story I would suggest that you help her to go strict keto/low carb to see how she does. You will know pretty soon. Start with the keto things you know she can tolerate. Maybe just ground beef, or steak with a few above ground veggies, chicken with the skin, again with lettuce or green veggies. Meat and veggies. Even have her sip bone broth and add some extra fat (if she can tolerate it) like melted butter. Keep it super simple for two weeks and then very slowly add back into her diet keto foods, like avocado, or cauliflower, that she thinks she cannot tolerate to see if that is still true.
    Get her to keep a food journal to record how specific foods impact her.
    Many of us who have had complete resolution of IBS are very surprised that food we thought were triggers can now be tolerated. It is almost , I think, like the keto diet reset the dysfunction of the gut and now we are not so sensitive. My symptoms, and issues with problem foods, come back if I add back in too many carbs or if I have a cheat time. So I stick to ketogenic eating because my gut feels so much better. Good luck. Let us know how it goes.
  17. Jude
    This is second hand info but speaking for my husband. He was diagnosed with ibd years ago. After reading the information sheet that accompanied the prescription he was given he chose to keep suffering. Approximately one year ago he joined me in a LCHF eating regimen and says symptoms are gone. He says what used to be a major event is now life as usual. Since there is nothing to lose with this way of eating I highly recommend trying it for a few weeks, seriously doing not “trying”.
  18. Cathy
    I suffer terribly from IBS and am definately going to try this. I am so sick of thinking about my stomach all day long. Wish me luck
  19. Liz
    For a few years now I have suffered IBS, in silence. Travel was a nightmare, incidents at work, etc. I have been on the two week challenge, barely a week now, and am shocked at the 99% improvement, I can't believe it! I have quit wheat, milk, ok with the cream though! processed foods, addiction to Splenda, and my T2 diabetes readings are in normal range, which they havn't been for 7 years! This has been very sustainable, love the recipes, and the taste of food now. I peeked at the scale today, down 10lbs already! My appetite has gone down dramatically as well. This is my miracle.
  20. Paula
    After having IBS-D for over 20 years (totally controlling my life) I’m finally able to leave home with confidence.
    After starting the Keto diet, my IBS-D issues are obsolete.
    I keep thinking any day now, my symptoms will return but I’m hoping and praying they don’t.
    Keto has been an answer to my prayers.
  21. Priya
    I think people with IBS-D should do their research before starting a high fat diet. I have read articles online which say that IBS-D sufferers may also suffer from bile malabsorption which hinders digestion of fats. I did Keto for 29 days and it made my diarrhea worse than before. Although I was losing weight, I felt like crap. So, please be mindful of that.
    Reply: #23
  22. Janice
    Does anyone had the issue of not making it to the bathroom ? How embarrassing!! Help !! Yes
  23. HELLEN
    Yes! I have been doing keto for months and couldn't figure out why I would feel good for a week and then bam, right back to an episode of ibsD. I think it's the high fats! I was having issues with fiber originally and cut back on them and felt better but realized I was missing out on healthy fats and have felt worse.
  24. Kkay
    Good experience with Keto, initially, first 6 weeks. Until I ate a low carb High fat pizza ( Cheese crust). Resulted in new, complete, rejection of Dairy, now. And IBS-D w Vomiting. Trying to get back to Keto after 3 weeks derailed. Seem to needing some low FODMAP foods occasionally. Such as Sweet or white potatoes, berries, etc.. Going to try a PREBIOTIC inulin a few times a week. Too much untrapped fluid in the large intestine.
  25. Cynthia C
    I have IBS-D, but it alternates sometimes between diarrhea and constipation-mostly diarrhea. Anyone got any advice for getting enough keto veggies without aggravating my IBS? I can tolerate them better when I'm constipated.

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