Endo Belly: Why You Look 6 Months Pregnant

You wake up with a relatively normal abdomen. By mid-afternoon, you look 6 months pregnant. Your pants don't fit. You can't button your jeans. The distension is so severe that strangers have asked when you're due.

And it has nothing to do with eating too much.

This is endo belly. And it's one of the most disorienting, invisible, deeply frustrating symptoms of endometriosis—because it makes you look sick while simultaneously being completely dismissed by people who don't see the clinical mechanism underneath.

"You just have IBS," a doctor might say, completely missing that this distension is qualitatively different from functional bloating. Or: "Try cutting out FODMAPs," which might help slightly but misses the deeper drivers.

I spent years thinking I was failing at digestion. It took understanding the actual mechanisms to realize my body wasn't broken—it was responding to inflammatory signals.

What Endo Belly Actually Is

Endo belly is visceral abdominal distension caused by multiple overlapping mechanisms, all rooted in inflammation. It's not just gas. It's not just swelling. It's a constellation of inflammatory processes happening simultaneously:

• Mast cell activation releasing histamine
• Gut dysbiosis feeding pathogenic bacteria
• Small intestinal bacterial overgrowth (SIBO)
• Increased intestinal permeability ("leaky gut")
• Visceral hypersensitivity making you perceive normal amounts of gas as severe distension
• Peritoneal inflammation and adhesions physically restricting gut motility

When all of these are happening at once, your abdomen doesn't just feel bloated—it visibly swells. This is why you can gain 10-15 pounds of apparent weight by evening, then wake up relatively normal. The distension is real. It's just not from fat storage.

The Mast Cell Connection

Mast cells are immune cells that live in your gut lining and peritoneum (the tissue surrounding your organs). When they activate, they release histamine—a powerful inflammatory mediator that causes vasodilation (blood vessels open), increased vascular permeability (fluid leaks into tissues), smooth muscle contraction (your gut tightens), and visceral pain perception amplification.

In endometriosis, mast cells are hyperactivated. Emerging research suggests that endo lesions themselves are rich in mast cells, and these cells are in a state of chronic activation. They're like security guards who have forgotten how to distinguish between actual threats and benign stimuli. A small meal triggers them. Hormonal fluctuations trigger them. Stress triggers them.

The result: your gut lining swells, fluid accumulates, gas production increases, and you distend. This happens acutely and repeatedly, not as a gradual process.

SIBO: The Hidden Culprit

Small intestinal bacterial overgrowth (SIBO) is a condition where bacteria that normally live in your colon start colonizing your small intestine—where they shouldn't be. These bacteria ferment carbohydrates and produce gas at a much higher rate than normal gut bacteria.

In one study, up to 91.9% of people with endometriosis tested positive for SIBO. Let me repeat that: 91.9%. This isn't a coincidence. This is a direct consequence of endo's inflammatory environment.

Here's the mechanism: Endometriosis causes dysbiosis (imbalanced gut microbiota). The protective bacteria are depleted. Pathogenic bacteria take over. These pathogenic organisms produce lipopolysaccharide (LPS)—an endotoxin that further damages gut lining integrity, creates more inflammation, and changes gut motility. Slower gut transit = bacterial overgrowth in the small intestine = gas production = distension.

And crucially: a standard probiotics approach doesn't fix this, because you're not just depleted of good bacteria. You have active bacterial overgrowth that needs to be treated specifically. This is why so many people with endo don't improve with standard IBS diets.

Dysbiosis and Leaky Gut

Your gut microbiota is supposed to be a diverse ecosystem of bacteria that support digestion, produce short-chain fatty acids (which feed your gut cells), produce neurotransmitters, and maintain barrier integrity.

In endometriosis, that ecosystem is devastated. You lose diversity. You lose the species that produce butyrate. You lose microbial metabolites that maintain tight junctions between intestinal cells. The result is increased intestinal permeability—"leaky gut."

When your gut is leaky, bacterial lipopolysaccharides cross the intestinal barrier and enter your bloodstream. Your immune system recognizes these as foreign and mounts an inflammatory response. This triggers systemic inflammation and further activates mast cells, creating a vicious feedback loop.

You end up with simultaneous distension from:

• Direct mast cell activation releasing histamine
• SIBO-produced gas
• Altered gut motility from dysbiosis
• Visceral hypersensitivity making you perceive the distension as worse than it objectively is

This is why eating a normal meal can cause dramatic distension. Your system is hyperresponsive at every level.

Visceral Hypersensitivity: The Perception Problem

Even if you had zero gas in your abdomen, you'd still feel bloated because of visceral hypersensitivity. About 41.4% of people with endometriosis develop central sensitization—a state where your nervous system amplifies pain and sensation signals from your organs.

Imagine you normally have a volume dial set at "3" for normal digestive sensations. In central sensitization, your dial is stuck at "9." A normal amount of gas feels excruciating. Normal peristalsis (gut contractions) feels like cramping. Your brain interprets a full stomach as a medical emergency.

This is why you can feel impossibly bloated after eating very little. Your perception matches an inflammatory reality, but the inflammation is being amplified by nervous system dysfunction. You're not imagining it. But it's also not purely mechanical distension.

Why Standard Bloating Remedies Don't Work

This is the frustration point for so many of my patients. They try everything:

• Probiotics: These help when dysbiosis is the only problem. But when you have SIBO, adding more bacteria (even good bacteria) can worsen the overgrowth.
• Fiber: Adding fiber when you have SIBO and dysbiosis feeds the pathogenic bacteria and worsens fermentation.
• Peppermint tea, fennel, digestive enzymes: These address symptoms, not mechanisms. They might help slightly, but they don't address the mast cell activation, dysbiosis, or SIBO.
• Generic low-FODMAP diet: This can help by reducing fermentable carbohydrates, but it's not a treatment—it's symptom management. The underlying dysbiosis and SIBO persist.

The problem is that most recommendations for bloating treat it as a functional issue. But endo belly is an inflammatory issue with bacterial overgrowth. You need to address the inflammation, treat the dysbiosis, and support nervous system recovery.

What Actually Helps

1. Address SIBO Specifically

This usually means SIBO-specific testing (breath test) and targeted treatment. Some people respond to herbal antimicrobials (oregano, garlic, berberine). Others need prescription antibiotics (rifaxomicin). The goal is to reduce bacterial overgrowth enough to restore normal motility and reduce fermentation.

2. Repair Your Microbiome

This is a sequential process:

• First: Remove or reduce pathogenic bacteria (via SIBO treatment)
• Then: Repair gut barrier with bone broth, L-glutamine, zinc carnosine
• Then: Rebuild diversity with specific, sequenced probiotics once the overgrowth is resolved
• Then: Support the bacteria you're restoring with prebiotics (inulin, FOS) in doses they can handle

This isn't about adding 47 supplements. It's about a logical sequence based on your microbiota's actual state.

3. Control Mast Cell Activation

Some strategies:

• Quercetin + DAO: Quercetin naturally inhibits mast cell degranulation. DAO is an enzyme that breaks down histamine. Both available over-the-counter.
• Low-histamine diet: Avoiding high-histamine foods (aged cheese, fermented foods, cured meats, alcohol) can reduce mast cell trigger load.
• Cromolyn sodium or ketotifen: Prescription mast cell stabilizers that actually prevent degranulation (not just manage symptoms).
• Addressing triggers: Stress, hormonal fluctuations, certain foods. What triggers your patient's mast cells might be different from what triggers someone else's.

4. Regulate Your Nervous System

Because visceral hypersensitivity is a nervous system problem, somatic approaches matter here:

• Pelvic floor physical therapy (to address guarding and hypertonicity)
• Vagal toning exercises (breathwork, specific yoga poses that activate the vagus nerve)
• Trauma-informed somatic work (because chronic pain creates trauma, and that trauma reinforces pain sensitization)

These aren't feel-good additions. They're essential components of addressing central sensitization.

5. Anti-Inflammatory Nutrition

Not a restrictive diet. An anti-inflammatory baseline:

• Omega-3 fatty acids (fish oil, algae)
• Polyphenol-rich foods (berries, dark chocolate, olive oil)
• Bone broth for collagen and gelatin to support gut barrier
• Curcumin + black pepper for reduced systemic inflammation

These aren't magic. But they're clinically supported ways to reduce the inflammatory burden your body is managing.