Low FODMAP Diet Mistakes That Can Make IBS Worse (And What to Do Instead)
The low FODMAP diet is often recommended for Irritable Bowel Syndrome (IBS). And it can be really helpful.
But here’s the part that doesn’t get talked about enough: done incorrectly, it can actually make your gut health worse over time.
So this isn’t just about doing it “right” to get results.
It’s about avoiding a situation where your symptoms (and your relationship with food) get more complicated.
The biggest misconception about the low FODMAP diet
The most common misunderstanding I see is this:
People think low FODMAP is a long-term diet.
It’s not.
This diet is meant to be temporary. It’s a tool used to:
Calm symptoms of abdominal pain, bloating, and diarrhea
Identify food triggers and sensitivities
And the most important part of low FODMAP is a slow, controlled reintroduction of all the foods you cut out. If you stop doing it willy-nilly, or you stay on it long-term, you’re missing the best part!
Does a low-FODMAP-lite diet work for IBS?
This is something I see a lot:
Someone half-implements the diet.
They see partial improvement, but not full resolution.
So they just… stay there.
Not feeling great. Not fully understanding why. And still dealing with daily symptoms.
And that may feel like “managing” your symptoms the best you can. But it doesn’t address the underlying causes of your digestive symptoms, so even though it’s not super restrictive, it’s not solving the problem either.
Can you stay on low-FODMAP long-term?
It always makes me sad when I see this in clinic.
Someone tries low FODMAP on their own.
Their symptoms improve dramatically.
It feels like a huge win.
But then they never reintroduce foods.
Years later, they’re still eating a highly restricted diet — and symptoms start creeping back in.
Now food feels stressful, unpredictable, and risky.
And unfortunately, they’re not eating any of the healthy fibres that are so important for gut and metabolic health in the long term.
How does the low FODMAP diet work?
A lot of people are told this diet works by “fixing the gut microbiome.”
That’s only part of the picture.
As the science of gut-brain interaction develops, we’ve learned more about the role of the nervous system.
In IBS, the gut develops something called visceral hypersensitivity. Basically, the gut becomes overly reactive to normal sensations. Things like normal amounts of gas, food moving through each part of the gut, and simple intestinal stretch start to feel painful or urgent.
FODMAPs are fermentable fibres: when bacteria break them down, they produce gas.
And gas production leads to intestinal stretch, which causes stimulation of a sensitive nervous system.
So when you reduce FODMAPs, the nervous system gets a break. A little holiday. Some time to relax, chill out, and stop losing its literal sh*t at normal things.
Then, you can reintroduce those foods. And suddenly, they don’t seem so spooky to the gut anymore. You can eat them without any of the pain or unpredictability you had before.
Sometimes you do react to one or two categories - and then we know what made your gut’s nervous system so anxious in the first place and you can avoid that true trigger food.
Why didn’t the low FODMAP diet work?
Remember the two main ways that people go wrong when they try to do low FODMAP on their own?
They don’t follow it closely enough (for long enough) ➡️ The nervous system never actually settles
They follow it too strictly for too long ➡️ This can cause:
Increased fear around food, by reinforcing the idea that certain foods are unsafe
Increased sensitivity in the gut
Reduced intake of important nutrients and fibres
Why low FODMAP doesn’t work for everyone with IBS
There’s also a third reason the low FODMAP diet may not work, which isn’t actually a mistake: the low FODMAP diet simply isn’t the right treatment option for everyone. That’s why having your digestive symptoms assessed by a knowledgeable healthcare professional is so important before starting any treatment on your own.
A good assessment should consider other causes of your symptoms, like SIBO, celiac disease, and inflammatory bowel disease, before assuming you have IBS. You definitely need a more in-depth assessment if you have symptoms that wake you up at night, blood in your stool, unexplained anemia, unintended weight loss, or a family history of Crohn’s Disease or Ulcerative Colitis.
Even if you do have IBS, low FODMAP may not be the right approach for you - this is where a healthcare provider like me can help you understand your best options.
As a naturopathic doctor in Ontario, I’m able to order most of the tests needed to rule out other causes of digestive distress. And if you have more concerning symptoms, I am always happy to work with your primary care provider to make sure more in-depth assessments, like colonoscopy, endoscopy, or abdominal ultrasound get done.
A safer way to approach low FODMAP (with less restriction)
When I guide my patients through the low FODMAP diet, there are two things I do a little differently.
Clear timelines
This is never positioned as a long-term diet.
There’s a clear plan for:
how long the elimination phase lasts
when reintroductions start
and what we’re looking for along the way
A diet without diet culture
This diet is restrictive. There’s no way around that.
So I make it as simple and flexible as possible.
That means my version only recommends foods that are actually low FODMAP (not low FODMAP if you only eat a small serving). This means you never have to limit how much you eat, or pull out the measuring cups.
For some people (especially those with a history of disordered eating) we skip this approach entirely. There are other ways to treat IBS and I make sure you know all your options.
IBS is treatable
It’s not just something you have to “manage” forever.
If you’re trying to piece this together on your own and feeling stuck, overwhelmed, or restricted… that’s not a personal failure. It’s a sign you need a clearer, more strategic approach.
Because the goal isn’t to live on a limited diet.
It’s to get you back to eating normally - without worrying about where the closest bathroom is.
I support people with IBS in my naturopathic practice in midtown Toronto and virtually across Ontario. If you’re ready to stop stressing about whether to try low FODMAP and actually get an individualized strategy to treat your IBS, book a discovery call with me to see how I can help.