5 Signs Your Bloating May Be SIBO, Not Just IBS
If you’ve been dealing with bloating that just won’t quit, you might have been told it’s “just IBS.” Irritable Bowel Syndrome (IBS) is a common label for digestive symptoms like bloating, abdominal pain, constipation, or diarrhea—but here’s the thing: IBS isn’t really a diagnosis on its own. It’s more like an umbrella term doctors use when they know your digestion isn’t right, but they’re not exactly sure why.
Under that umbrella are a lot of possible root causes—stress-related gut sensitivity, food intolerances, post-infection changes to digestion, hormonal imbalances… and one of the biggest and most overlooked causes: Small Intestinal Bacterial Overgrowth (SIBO).
SIBO happens when bacteria—often the same kind that normally live in your large intestine—end up growing in your small intestine, where they don’t belong. These bacteria ferment the food you eat, producing gas and inflammation right in the upper part of your digestive tract. The result? Bloating, discomfort, and a range of other IBS-like symptoms.
In fact, research suggests that SIBO may be the underlying cause in well over half of all IBS cases. Which means if you’ve been told you have IBS, but you still feel terrible despite trying different diets, medications, or probiotics, it could be SIBO driving your symptoms.
So—how can you tell? Let’s break down the five biggest signs your bloating might actually be SIBO.
1. Your Bloating Gets Worse as the Day Goes On
With SIBO, many people notice they wake up with a fairly flat stomach, but by evening, they look (and feel) several months pregnant. This is because the bacteria in your small intestine are actively fermenting your meals and snacks throughout the day, building up more and more gas.
IBS can cause bloating too, but SIBO bloating tends to be progressive—each meal adds more fuel to the bacterial “fire,” and by nighttime, you’re so distended that your clothes feel tight and uncomfortable. If your bloating follows this morning-to-night pattern, it’s a classic red flag for SIBO.
2. Your Bloating Starts Quickly After Eating
If you notice you start feeling bloated within minutes after a meal, that’s another big clue. With SIBO, food reaches the overgrown bacteria in your small intestine very quickly, so fermentation (and gas production) can happen fast.
By contrast, with IBS from other causes, bloating can be more delayed, showing up hours later, often due to slower digestion, food sensitivities, or stress-related gut changes.
Quick onset bloating—especially after eating foods high in fermentable carbs like garlic, onions, beans, or wheat—is a hallmark SIBO symptom.
3. You Have a Mix of Constipation, Diarrhea, or Both
IBS comes in different types: IBS-C (constipation-dominant), IBS-D (diarrhea-dominant), and IBS-M (mixed). SIBO can mimic all three.
Methane-dominant SIBO tends to slow down the bowel, leading to constipation, incomplete bowel movements, and a heavy, sluggish feeling.
Hydrogen-dominant SIBO usually speeds things up, causing loose stools or urgent diarrhea.
Mixed gas SIBO can cause unpredictable swings between the two.
If you’ve been told your bowel habits are “just IBS,” but you notice they’ve changed over time—or you flip between constipation and diarrhea—it’s worth testing for SIBO.
4. You Feel Relief (Temporarily) When You Skip Meals
Many people with SIBO notice that their bloating and discomfort ease up when they fast or space out their meals. That’s because without incoming food, there’s nothing for the bacteria to ferment, so gas production slows down.
Of course, skipping meals isn’t a long-term solution (and can make you feel weak or irritable), but if you’ve accidentally noticed your gut feels calmer when you delay eating, it’s a potential clue that bacteria—rather than just gut sensitivity—are behind your symptoms.
5. You’ve Tried “IBS-Friendly” Changes but Still Feel Miserable
A lot of people with IBS see some improvement from things like stress management, increasing fiber, or following a general “healthy gut” diet. But with SIBO, these same strategies can sometimes make things worse.
High-fiber foods (beans, lentils, bran, certain fruits and veggies) can feed the bacterial overgrowth.
Some probiotics can actually increase bloating if they contain strains that thrive in the small intestine.
Even stress reduction, while important, doesn’t address the root problem if the real issue is bacterial overgrowth.
If you’ve been diligent about your diet and lifestyle changes but your bloating is just as bad—or worse—it’s time to consider SIBO testing.
What to Do If You Suspect SIBO
If these signs sound familiar, the next step is to get properly tested. The most common test for SIBO is a breath test, which measures hydrogen and methane gases after you drink a special sugar solution. These gases are produced when bacteria ferment the sugar in your small intestine.
SIBO treatment typically involves a three-phase approach:
Prepare the gut – Calm inflammation, improve motility, and make the environment less hospitable for overgrowth.
Clear the overgrowth – Using targeted antimicrobials.
Restore and prevent relapse – Heal the gut lining, rebalance the microbiome, and maintain healthy motility so bacteria don’t creep back in.
This is where working with a naturopathic or integrative practitioner can make a big difference. The right plan is personalized—what works for one person may not work for another, depending on the type of SIBO, other gut issues, and your overall health.
The Bottom Line
IBS is a broad label, but it’s not a root cause. If your bloating follows a predictable daily pattern, starts soon after meals, changes with fasting, and hasn’t improved despite your best efforts, SIBO might be the missing piece of the puzzle.
You don’t have to live with that uncomfortable, stretched-to-the-limit belly every day. With the right testing and a targeted plan, it’s possible to treat SIBO and finally feel lighter, more comfortable, and in control of your digestion again.
Ready to make a change?
Book a complimentary 15-minute consult to learn how naturopathic care can help you determine what’s happening with your digestive health and address these symptoms with confidence. We’ll discuss your concerns, review what testing might be helpful, and explore personalized strategies to support your digestion, energy, and long-term health.
Be well,
Dr. Mitchell Schroeder, ND