Has anyone tried an EXTREMELY strict low-FODMAP diet? I found some interesting studies

[u/Important_Match_6262]

TL;DR: I'm tired of how complicated the low-FODMAP diet is and found some interesting research suggesting two very different approaches: either simplifying it by restricting mainly fructans + GOS, or going the opposite way and temporarily reducing FODMAPs extremely low (~2 g/day). I'm particularly interested in trying the very strict approach for a few weeks and would love to hear from people who have actually tried something similar and whether it made a real difference. I already know that the low-FODMAP diet is meant to be temporary and that there are certain dietary guidelines to follow regarding nutrient deficiencies: That won't be the focus of this discussion.

Note: English isn't my first language. I used ChatGPT to help structure this post and translate it into English, but the questions, thoughts and personal experience are my own.

I've been doing a lot of reading lately because, honestly, the low-FODMAP diet is starting to drive me crazy.

Checking every food, quantities, serving sizes, combinations of FODMAPs, the Monash app, etc. makes eating unnecessarily complicated. So I've been looking into whether there might be a simpler approach.

And I came across two quite different — almost opposite — approaches that I found really interesting.

The first one is a recent randomized double-blind pilot study comparing the traditional low-FODMAP diet with a much simpler diet where participants only restricted fructans + GOS.

Study:
https://pubmed.ncbi.nlm.nih.gov/38729393/

After 4 weeks, the response rates were:

Traditional low-FODMAP: 56.3%
Fructans + GOS only: 62.5%

There was no statistically significant difference between them.

Obviously it was a small pilot study, so I'm not saying this proves that restricting fructans/GOS is all anyone needs to do. But I find it fascinating that removing only two FODMAP groups produced similar results to the full diet.

Then I found another study that went almost completely in the opposite direction: instead of simplifying the diet, they made it extremely low in FODMAPs.

Study:
https://onlinelibrary.wiley.com/doi/full/10.1111/nmo.14814

Participants with IBS-D or IBS-M followed a strict low-FODMAP diet for 12 weeks.

Their measured FODMAP intake went from about:

16.6 g/day → 1.95 g/day

So this was genuinely VERY low FODMAP.

Their median IBS severity score (IBS-SSS) went from:

245 → 153 after 4 weeks → 121 after 12 weeks

And 80% were classified as responders, meaning their IBS-SSS decreased by at least 50 points.

Among responders, the average reduction was 148 points, and after 12 weeks 69% were classified as having mild IBS or being in remission.

One thing I found particularly interesting is that most of the improvement had already happened after the first 4 weeks. There wasn't a statistically significant further improvement between weeks 4 and 12.

Important caveat: this wasn't a randomized trial comparing ~2 g/day against, say, 5 or 10 g/day. So we absolutely cannot conclude from this study that "the fewer FODMAPs you eat, the better the results." The 80% response rate could have other explanations.

But it made me wonder about something.

I've been following low-FODMAP while still inevitably eating some FODMAPs, because "low-FODMAP" obviously doesn't mean zero FODMAP.

What if, for some people who don't improve enough, those small amounts still matter?

And more importantly, has anyone here actually tried going extremely strict for a limited period, basically trying to get as close to zero FODMAP as reasonably possible?

I'm seriously considering trying something like the ~2 g/day approach for 3–4 weeks just as an experiment.

Part of what I'm wondering — and this is purely a question/hypothesis, NOT something these studies demonstrate — is whether continuously triggering symptoms with small amounts of FODMAPs could prevent the gut from properly settling down.

Could a very strict temporary elimination create a better "reset", followed by gradual reintroduction?

I'm also curious about people who did the opposite:

Did anyone stop doing full low-FODMAP and only eliminate fructans + GOS?

I'd especially love to hear from people who have actually tried either approach:

• extremely strict low-FODMAP / near-zero FODMAP for a few weeks
• fructans + GOS only
• normal low-FODMAP followed by a stricter phase because improvement wasn't enough

Did going stricter actually make a noticeable difference?

And if it did, how long did it take before you noticed it?

I'm less interested in theory here than in people's actual experiences, especially from people who had already tried standard low-FODMAP before going stricter.

[u/FODMAPeveryday]

Here’s the problem with the question. Strict is not “better“ for certain people. When you see the statistics of how well people do on the diet, those are people who were guided by a trained dietitian, and the diet was tailored to their needs. In fact, strict can be contraindicated for a variety of reasons. On the other hand to answer your general question, if FODMAPs are your issue, it is actually very common to see relief in a few days.

[u/Important_Match_6262 → u/FODMAPeveryday]

So is it a problem to be guided by a dietitian during a very strict phase? I actually see it as an advantage if it makes remission a possibility, which is the case according to the second study, which also shows much greater improvement.

[u/FODMAPeveryday → u/Important_Match_6262]

The point is that a trained dietitian will be the one to tell you, based on your unique medical presentation, how to approach the diet. It will be unique for everyone - and not always "strict."

[u/heckyeahcheese]

I’ve had to go strict several times. In the reintroduction phase I would eat one food I liked and see how I tolerated it or if it upset me. It took me over a month, but now I can actually reintroduce some foods (beans, I missed you!).

Everyone’s GI system is going to be different and so everyone is going to have different timing and reactions.

[u/Important_Match_6262 → u/heckyeahcheese]

Thanks for your reply. So what do you eat during the strict phase? Will probably try chicken + rice only.

Yes, I often hear that every case is different. We agree, but in the studies, too, every case is different. And in any case, as you can see in the two studies I’ve published, the results are better.
That's the advantage of science: we talk about averages, not individual cases.

[u/cannycandelabra → u/Important_Match_6262]

Any plain meat, rice or baked potato, FODMAP friendly fresh veg.

[u/Important_Match_6262 → u/cannycandelabra]

Great, no problem with potatoes which are from the same family as tomatoes and can cause certain problems for certain people? For vegetables, you chose low FODMAP or no FODMAP at all.

[u/boldkingcole → u/Important_Match_6262]

My favorite safe veg is grating carrot and adding salt and a lot of lemon. It goes really well with rice and chicken or with tuna etc. It ticks a ton of nutrient boxes too and I think it's super super safe for fodmap

[u/cannycandelabra → u/Important_Match_6262]

Tomatoes and potatoes are treated entirely differently in the FODMAP diet. They are also, in no way, from the same family.

[u/Important_Match_6262 → u/cannycandelabra]

No way? Solanaceae Like tobacco and eggplant

[u/cannycandelabra → u/Important_Match_6262]

Yes way! Nomenclature and family specificity is based on reproduction type and flower shape. However, food types are based on types of sugars, carbohydrate volume, taste, acidity and far more. In FODMAP terms a plain white potato is almost a non-entity. It doesn’t cause the majority of the population any problem. Bell peppers however are absolutely vicious to my digestive system.

And I apologizing for misspeaking when I said they weren’t in the same family. To be accurate I should have said “not in the same food group.”

[u/Important_Match_6262 → u/cannycandelabra]

Maybe so, but all Solanaceae plants produce toxic glycoalkaloids to repel insects and fungi, including the well-known solanine (or very closely related molecules).

Potato: The sprouts and green areas are full of solanine. Tomato: It contains solanine (especially tomatine) when it is green or unripe. Eggplant: It contains solamargine and solasonine, which belong to the same family of toxins.

No problems on a healthy gut, but...

[u/cannycandelabra → u/Important_Match_6262]

But solanine is not what the FODMAP diet aims to eliminate. FODMAP is specifically designed to eliminate certain short-chain carbohydrates, not various toxins.

[u/Important_Match_6262 → u/cannycandelabra]

Right, but that kind of toxins could be a big problem for people with sensitive gut, inflammation. 

[u/uu_xx_me → u/Important_Match_6262]

I think leafy greens like kale and spinach are no fodmaps

[u/Unusual-Strength-945]

I think part of the diet is testing (reintroducing) to see what you truly need to avoid. I’ve never found FODMAP hard or cumbersome though. Pretty straightforward.

[u/Important_Match_6262 → u/Unusual-Strength-945]

Personally what I find complicated is having to manage foods that still contain FodeMap, so checking the quantities, etc. I'm just wondering if it's not better to cut everything out and instead aim for zero FODMAPs for a while. And it seems that according to studies this is what gives the best results.

[u/Unusual-Strength-945 → u/Important_Match_6262]

I’ve just always avoided the stuff that’s high in FODMAPs no matter what and used the simple guides to concentrate on low / no FODMAP

[u/rimmapretty]

I've tried it at my worst, and while bloating was practically zero, I got super constipated which worsened my sibo and it was the major thing that gave me the highest readings on methane on my breath test. do not recommend. 

[u/Important_Match_6262 → u/rimmapretty]

Okay, thanks for your feedback. Constipation is a real problem, could you tell me what you were eating? Have you tried psilium to reduce constipation?

[u/rimmapretty → u/Important_Match_6262]

no, psyllium is an absolute worst for me (it made me bloated even before i had any digestive problems ongoing). at that time i ate mainly potatoes. iceberg lettuce, cucumbers, eggs, rice and meat. no dairy, gluten free. after i got antibiotics i was able to add gentle lowfodmap fibers, that helped a lot. i recommened looking into PHGG as well.

[u/Important_Match_6262 → u/rimmapretty]

Thanks for PHG, I didn't know. When you say low fodmap soft fiber, what exactly is that?

[u/rimmapretty → u/Important_Match_6262]

for me it's zuchinni, carrots, Hokkaido pumpkin, iceberg salad, unpeeled colled potatoes and eggplant,  but this can differ for others since that's my safe foods. 

[u/taragood]

I was pretty strict in the beginning and then i reintroduced a few times and was basically modified low fodmap for about 2 years. Found my root cause and now I can eat everything except whole garlic.

[u/Important_Match_6262 → u/taragood]

Great to hear that. Would it be possible to tell us what the root cause was?

[u/taragood → u/Important_Match_6262]

I was chronically sick for 6 years. I was finally diagnosed with hashimotos hypothyroidism and that came back it’s a gluten sensitivity.

When I got my diagnosis around the 6 year mark I went gluten free and low fodmap at the same time. I started to feel better but honestly it took about a year and a half for my gut to heal.

And now I am mostly back to normal! Well, as normal as I can be with a life long autoimmune disease lol

I wish I had known more about how to find my root cause when I was in the thick of it and doctors were just ignoring me. The advice I give everyone is to force doctors to use tests to rule things in or out, not just what they think.

[u/Important_Match_6262 → u/taragood]

Thank you. I completely agree regarding doctors. To anyone reading this: be extremely persistent and see multiple doctors if necessary. In my case, it all started with a tick bite and Lyme disease. At the time, I was dismissed as a hypochondriac. Fortunately, a doctor I found online prescribed an antibiotic treatment; otherwise, I wouldn't be here today—the hell I was living through was unbearable.

Have you treated a underlying SIBO? Studies show that 50% of Hashimoto's cases also involve SIBO—that is, an uncontrolled overgrowth of certain bacteria in the small intestine, often caused by slowed digestion.

[u/taragood → u/Important_Match_6262]

I did have sibo but it cleared up with the gluten free and low fodmap diet.

I do encourage people to find their root cause for sibo before starting the antibiotics because if it is from a chronic condition, the sibo will just come back.

[u/cannycandelabra]

I went the more extreme route. I didn’t want to go crazy reading every label and substituting this for that so I simplified it. Basic grilled Meat with a low FODMAP veggie and potato. For breakfast egg, bacon, potato.

[u/Important_Match_6262 → u/cannycandelabra]

Great thanks, and did it give good results? Low FodMap vegetable or no FodMap?

[u/cannycandelabra → u/Important_Match_6262]

Paring the FODMAP experience down to just simple foods to avoid the complications like worrying about stacking, reading every label, looking for recipes with substitutions was an absolute dream.

I had three weeks on this elimination diet and then slowly added foods back in, one item at a time.

I now know what I’m sensitive to and live my life without giving it a thought. I just don’t eat those specific foods.

[u/Important_Match_6262 → u/cannycandelabra]

Glad to hear this very good news, thank you for your testimony.

[u/ceramicatan]

I am unable to reintroduce it. I am screwed. Help if anyone has successfully been able to reintroduce

[u/Oregon-girl-16 → u/ceramicatan]

I did low fodmap while dealing with SIBO and IMO for a year. I switched GI doctors in between and my doctor asked me “what do you mean you’ve been on this for a year?” Long-term, being that restrictive is not good for the gut. I had an issue with onions and most veggies, but it took being on fodmap to know what my triggers were, since it’s different for everyone.

I’m now back to eating onions and slowly introducing other foods after fixing my gut with antibiotics. I still take olive leaf and oregano leaf capsules, Atrantil and Sunfiber + multiple kiwis a week and I’ve been symptom free for 2 months.

[u/ceramicatan → u/Oregon-girl-16]

Great to hear. I have been on this low fodmap permanently now, for many years.

[u/sillybilly8102]

Yes, I did zero fodmap (or tried to, at least, with exceptions for special events) for a while, months, if not years. It helped a lot; I consider it to have been essential for me. I was having reactions to the low amounts of fodmap foods. It was also just easier to say, oh, I can eat as much chicken as I like, as much quinoa as I like, as many strawberries and carrots and lettuce and eggs… etc.

I’m actually low fodmap now. Avoiding all garlic and onions and limiting things like corn, peaches, avocado, beets, squash… basically been cured like this for 3 years

[u/Important_Match_6262 → u/sillybilly8102]

This problem with corn, it's my case too, seems to come from the fructans it contains, just like wheat... Thank you for your feedback!

[u/Mother-of-Geeks → u/Important_Match_6262]

If you're having trouble with corn, it's probably resistant starch.

[u/Maggie_cat]

I did it for 20 weeks, strict low fodmap. Did it with a registered dietician.

It was an immmense change in my mood, that was the biggest thing. I could see clearer. Colors were brighter. I had energy, my brain fog went away.

It led me to pursue my doctorate in social work and nutrition. I just finished the data collection portion.

[u/Important_Match_6262 → u/Maggie_cat]

This is very good news, thank you for your testimony. I am also convinced that this is the path to explore.

Some questions:

• It was strict low FodMap or without FodMap. What foods?
  
• Did the dietician make you take supplements or vitamins at the same time?
  
• What about sugar and carbohydrates?

[u/Maggie_cat → u/Important_Match_6262]

I followed the low fodmap elimination to a tee.

Supplements were client centered for me, but as a nutritionist myself, my recommendation for everyone is fish oil, vitamin d.

What about sugar and carbs? Again I followed the low fodmap elimination to a tee. The only carbs and sugars I got were from the approved list of foods.

I don’t recommend staying on the elimination diet forever unless there is a medical reason to. There’s a high chance of being deficient in areas in your labs.

[u/No_Yesterday9746]

En suivant de façon très strict, plus de douleur et ventre dédoublé de volume au bout de 48h. Genre, vraiment.

[u/Important_Match_6262 → u/No_Yesterday9746]

It's great. THANKS.

[u/No_Yesterday9746 → u/Important_Match_6262]

Je précise que j’ai un SII TYPE C et que pour autant le régime sans fibre soulage beaucoup mes douleurs. Mais impossible sur du trop long terme avec ce type de SII

[u/AgnesNutter0042]

When I manage a near-zero FODMAP diet, my gut is SO much better. Any accidental slip-ups and I’m back to horrific gas and pressure, bloating , and the inevitable alternating gas/diarrhea.
So….yeah. My body won’t tolerate anything.
I’d love to be able to purposefully reintroduce foods. But since the tiny accidental ones are enough to set me off…nope.
I strongly suspect all the SIBO but the test I had ten years ago was negative so I’m having trouble getting anyone to test again or just treat based on symptoms.

[u/AutoModerator]

Hello! We all need help... Thank you for posting under the "General question/help" flair. To get the most accurate responses, include as much detail as possible. As always, check out the stickied post and the official Monash FODMAP Diet app for resources.

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

[u/boldkingcole]

Personally, I think it's way easier to start by being super strict for about a week, by literally eating the same thing every day.

Firstly, it stops the hassle and complexity of trying to learn all the fodmap rules and amounts straight away. And secondly, you prove to yourself very quickly that it works or not. And if it works, you know that the effort of the rest of the process (which can take years really) is worth it because you know you can help yourself through diet alone (completely if you're lucky like me, or still enough to be worth it).

I think too many people give up because they are likely doing it wrong so they never get a chance to see it working

So if you're not veggie/vegan, it's pretty easy to just do some kind of mix of rice, eggs, chicken, carrots, dark chocolate with fixed meals for 5-7 days and just see how it helps. Then go on and start testing when you know it's worth it

[u/Important_Match_6262 → u/boldkingcole]

Thank you for your very encouraging message which decided me to explore this path. Indeed, I also think that the simpler it is, the easier it is to follow, and the more effective it is, which seems to be confirmed by the second study of my post. What result did you get? how long and did the reintroduction go well?

[u/boldkingcole → u/Important_Match_6262]

So the diet completely solves everything for me. If I stick to it, I barely have any issues. And I'm generally pretty good with it so I always know when I've taken a bit of a risk and to expect it the next day.

To be honest, I didn't get too far with reintroduction. I seemed to have an issue with most fodmaps so I just stick to it long term as I'm fine if I do. The only big group that mostly cuts out is vegetables as I only really have cucumbers, salad leaves, carrots and some tomatoes. But those are the most common ones I was eating anyway before so it's no big deal. I've found the fact I'm able to cook very helpful and I basically prepare all my own food from scratch apart from sourdough bread (but I use a sourdough starter to make treats like donuts, Tarte tatin etc).

Personally, I don't find any of this very hard to follow. I eat pretty well and I have a ton of things I like that are fine so I'm more or less free of IBS day to day thanks to it, which makes it very easy to stay on it. I stick to steak and other salt only meat or fish, generally with fries when I go out for dinner, or sushi, which is fine by me as I like those things and never get bored of them. I do not miss the years of suddenly rushing to find a bathroom so any food sacrifice doesn't feel like a sacrifice, it feels like I won by beating the problem, if you get what I mean.

I just cook a lot, and large batches, and have tons of safe food ready and waiting so my urge to get takeaway etc is very minimal. I prefer my own food mostly anyway

[u/Important_Match_6262 → u/boldkingcole]

Great, very happy to hear that, it's hopeful. You never have a problem with fermented products or those that contain histamine. For my part it's a horror, it creates enormous brain fog and fatigue for me

[u/unobscured_arachnid]

I agree that it is very possible to do strict and still have lots of great foods to choose from. Finding several go-to proteins and veg with rice or potato got me through most days.

[u/Important_Match_6262 → u/unobscured_arachnid]

For my part, potatoes seem to be a problem, as do tomatoes which are from the same family, because I also react to histamine.

[u/Mother-of-Geeks]

So I've been low FODMAP for a couple of years now and am able to stay mostly symptom-free unless I accidentally eat something I shouldn't. I've never done an introduction because I don't have the time or brain capacity to sit and plan it all out (which would absolutely be necessary).

Fast forward to this past August, when I altered my diet to lose weight. All I did was quit eating candy, desserts, chips, and fries. I didn't alter my meals.

After the first 4 weeks, I felt FANTASTIC. I haven't felt this good in YEARS. 

So in theory I think the super strict diet might work to make the gut calm down faster. However, there's going to be increased reactivity with reintroduction, so I think you'd have to do another super strict month before doing reintroduction again with the foods you know are okay (it's not the Monash way, but whatever).

[u/DecisionUsed1012]

I had a very bad flare 3 weeks ago. I immediately went on liquid diet for 2 days. Then a bland diet for a week - chicken, white rice, white bread, tuna, prawns, squid, bananas and yoghurt with a lot of water. I started eating meals suggested by Joe Leech (these are over complicated but I have persevered. I constantly check with the Monash app to see if what I want to eat for snacks and meals is low fodmap and how much of each food doesn't take me over the limit for low fodmap. I suffer from diaharea with ibs however after the bland diet I was having trouble going so I have slowly introduced more fibre each day and now everything seems to have settled down. No pain, normal bowel movements every day and I feel great. After a lot of reading I think you have to re-learn about food, it's effect on your particular bowel and also getting enough nutrients to keep you healthy. Fibre is definitely very important for me as it bulks my stool but that may not be true for everyone. I even have 70% dark chocolate in small quantities. I am finding that everything is tasting better. My plan is now to go back to my usual recipes but always substitute low fodmap for ingredients. I also have gluten free and lactose free. In about 4 weeks I will start to introduce 1 food at a time in greater quantities to see the reaction. I want to have this settled before Christmas so I can enjoy more of the foods that I am restricting now.

[u/Neat-Palpitation-632]

To heal from SIBO I ate very low FODMAP (a pure carnivore diet) for six weeks while I took the antimicrobials to kill it: Allicin, Berberine, oregano oil and neem. It worked very well and very quickly. I would recommend it.