Reflections - 5 Signs Your IBS Might Actually Be SIBO

For a lot of people living with IBS, there’s a quiet sense that something about their diagnosis doesn’t quite add up.
Maybe you’ve been told your symptoms are “just IBS,” but the flare-ups feel too reactive, too sudden, too tied to meals.
Maybe you’ve tried eating healthier, cutting foods out, adding supplements, taking probiotics, yet your symptoms stay stuck in the same pattern.

If this feels familiar, you’re not alone.
And there’s a reason your experience hasn’t matched the label.

A significant number of people diagnosed with IBS actually have something else happening underneath, something that isn’t often explained, yet is incredibly common.

SIBO.
Small Intestinal Bacterial Overgrowth.

And while the name sounds intense, the concept is surprisingly simple.
Bacteria have moved into a part of the gut they shouldn’t be in, and they’re fermenting your food too early.

The result is gas, pressure, bloating, pain, and bowel changes, often within an hour of eating.

The tricky part is that SIBO is misdiagnosed as IBS. If you look closely at your symptoms, your body may already be giving you clues.

Here are five of the most helpful ones.

1. Your bloating appears quickly, not hours later

Most IBS bloating happens in the large intestine, after food has travelled through the stomach and small intestine.
This means the swelling tends to happen later in the day or long after eating.

But SIBO is different.

With SIBO, bloating often appears within 20 to 90 minutes of a meal.
It’s the kind of bloating that feels sudden.

Clients describe it as:

“I suddenly look 8 months pregnant.”

“My belly goes from flat to huge in an hour.”

“It doesn’t matter if it’s salad or soup, I bloat anyway.”

This rapid timing is one of the clearest signals that bacteria in the small intestine are fermenting food too early.

2. You react to foods that are supposed to be healthy

This is the part that confuses most people.

You try to eat well.
You choose whole foods.
You add fibre.
You include beans, lentils, garlic, onions, apples, all the foods the internet says are nourishing.

And somehow, things get worse.

With SIBO, this makes perfect sense.

Foods rich in fermentable carbohydrates (FODMAPs) feed bacteria.
Not a problem when those microbes live in the large intestine, but a huge issue when they live too far up.

This can show up as:

  • bloating after salad

  • discomfort from vegetables

  • reacting to avocado, garlic, onions, chickpeas

  • feeling full but distended

  • healthy meals leaving you worse than “unhealthy” ones

It’s not the food.
It’s where the bacteria are living.

3. You feel full quickly, yet hungry again soon after

This is a subtle but incredibly telling sign.

When bacteria overgrow in the small intestine, the movement of the gut slows.
It takes longer for food to leave the stomach, and the system becomes sluggish, almost heavy.

Your body might send signals like:

  • early fullness

  • pressure under the ribs

  • feeling like food “sits there”

  • a tight, swollen upper belly

But because digestion isn’t completing properly, you may find yourself hungry again shortly after.

This isn’t about willpower or appetite.
It’s a motility issue.

And motility is one of the core root causes of SIBO that often gets missed.

4. Your bowel habits are unpredictable, or stuck

You can experience any one of the following with SIBO:

  • constipation

  • diarrhoea

  • mixed type (constipation and diarrhoea)

This is why so many people are misdiagnosed.

When bacteria ferment food in the small intestine, they produce gases like methane or hydrogen, both of which influence the nerves and muscles lining the gut.

Methane SIBO often leads to constipation.
Hydrogen SIBO often leads to diarrhoea.
A mixture can lead to alternating patterns.

If your bowel habits feel unpredictable, reactive, or unusual for you, SIBO may be part of the picture.

5. Probiotics may make your symptoms worse

This clue is often overlooked.

Probiotics can be wonderful for the large intestine, but if bacteria are already overgrowing in the small intestine, adding more microbes (even “good” ones) can intensify bloating and discomfort.

This doesn’t mean probiotics are bad.
It simply means your gut might need a different approach right now.

Clients often tell me:

“I’ve tried every probiotic and they all make me worse.”

“I felt bloated within days of starting one.”

“I thought probiotics were supposed to help, but they don’t.”

If this sounds familiar, it’s not a failure.
It’s a pattern, and it’s often a SIBO pattern.

So what does this mean for your IBS?

If these signs are familiar, it doesn’t automatically mean you have SIBO. But it does mean it’s worth exploring the possibility.

Because if SIBO is part of the picture, no amount of dieting, restricting, or random supplements will resolve the root cause.

The key is addressing:

  • motility

  • inflammation

  • bacterial overgrowth

  • digestive capacity

  • nervous system patterns

  • overall microbial balance

And doing so in a way that the body can actually tolerate, rather than pushing it harder.

When all these layers are supported, symptoms often shift more quickly than people expect.

A final note

You’re not imagining your symptoms.
You’re not overreacting.
And you’re not “bad” at managing IBS.

Many people spend years trying to fix the wrong issue, often because no one connected the dots for them.

Your symptoms make sense.
Your patterns have a reason.
And your body is not malfunctioning. It is responding.

If SIBO is part of your story, healing is absolutely possible with the right, gentle, structured approach.

Amanda Callenberg