Why Am I Always Bloated? Causes and Fixes | Nutritionist
You wake up flat. By mid afternoon your waistband is uncomfortable, and by evening you look several months pregnant. It happens whether you eat a salad or a sandwich. You have cut out gluten, then dairy, then onions, and the pattern persists. Somebody has told you it is stress, and somebody else has told you it is normal.
Bloating is extremely common and it is not normal. It is a symptom with identifiable mechanisms, and in most cases the timing of it tells you a great deal about which mechanism is yours.
This article sets out what bloating actually is, what the pattern reveals, which tests are worth doing, and the small number of symptoms that mean you should see a doctor before changing anything about your diet.
In this article:
Why bloating and distension are not the same thing
What the timing of your bloating points to
The six causes behind most cases
Why cutting out more foods usually stops working
The tests worth doing, and the ones that are not
What to change first
The symptoms that need medical investigation rather than a diet
What is bloating?
Bloating is the subjective sensation of abdominal pressure or fullness. Distension is the measurable increase in abdominal girth. They often occur together, but not always, and the distinction matters clinically.
Someone can feel intensely bloated with no measurable change in girth, which points towards visceral hypersensitivity, meaning the gut is sending normal signals that the brain is amplifying. Someone else can distend visibly without much discomfort, which points towards a mechanical or motility problem.
When I ask people to photograph their abdomen in the morning and again in the evening, the answer is usually obvious, and it changes what we investigate.
Clinical note: the volume of gas in the abdomen of people with severe bloating is, in most studies, no greater than in people without it. What differs is how that gas is distributed, how the abdominal wall responds to it, and how strongly the signal is perceived. This is why "I must be producing too much gas" is usually the wrong starting assumption.
What does the timing of bloating tell you?
This is the single most useful question, and almost nobody is asked it.
When it happens | What it points to | Worth investigating |
Within minutes of eating, before digestion could plausibly occur | Swallowed air, eating speed, or abdomino-phrenic dyssynergia | Eating pace, carbonated drinks, chewing gum, breathing pattern |
30 to 90 minutes after eating | Fermentation high in the small intestine | SIBO, carbohydrate malabsorption |
4 to 8 hours after eating, or in the evening | Fermentation in the colon, slow transit | Constipation, fibre type and quantity, dysbiosis |
Flat in the morning, progressively worse through the day | Classic functional distension | Abdomino-phrenic dyssynergia, visceral hypersensitivity |
Follows the menstrual cycle | Progesterone slowing gut motility in the luteal phase | Hormonal pattern, not a food problem |
Constant, unrelated to meals, new in the last few months | Not a functional pattern | Needs medical assessment. See the red flags below |
What causes bloating?
1. Small intestinal bacterial overgrowth
Bacteria that belong in the colon colonise the small intestine, where they ferment carbohydrate much earlier in digestion than they should. The gas is produced in a narrower, less compliant space, which is why SIBO characteristically bloats people within an hour of eating rather than at the end of the day.
It is diagnosed by breath testing, and it is frequently missed because the symptoms overlap almost entirely with irritable bowel syndrome. I have written on how to tell the two apart.
2. Constipation, including the kind you do not notice
Stool in the colon is a substrate for fermentation and a mechanical obstruction to gas transit. You do not need to be severely constipated for this to matter. Daily bowel movements that are incomplete produce the same effect, and most people who describe themselves as regular have never been asked whether evacuation feels complete. The relationship with chronic constipation runs both ways.
3. Carbohydrate malabsorption
Lactose, fructose and the fermentable carbohydrates grouped as FODMAPs are poorly absorbed by some people and arrive in the colon intact, where bacteria ferment them. Lactose intolerance is the most common and the easiest to establish. FODMAP sensitivity is real but is a symptom, not a diagnosis: the question worth asking is why fermentation is producing symptoms now when it did not before.
4. Abdomino-phrenic dyssynergia
This is the mechanism most people have never heard of, and it explains the cases that make the least sense.
In normal digestion, when gut contents increase, the diaphragm rises and the abdominal wall contracts, accommodating the volume without visible change. In abdomino-phrenic dyssynergia the opposite happens: the diaphragm descends and the abdominal wall relaxes, pushing the abdominal contents forward. The result is dramatic visible distension from an entirely normal volume of gas.
It responds to biofeedback and breathing retraining rather than to dietary restriction, which is why people with this pattern eliminate food after food and get nowhere.
What is frequently missed: if your bloating is visible, worsens through the day, and has not improved despite removing gluten, dairy, FODMAPs and everything else, the problem may not be what you are eating. It may be how your abdominal wall and diaphragm respond to normal digestion.
5. Dysbiosis and low stomach acid
An altered microbial community ferments differently. Dysbiosis changes which gases are produced and in what quantity, and reduced stomach acid, whether from long term acid suppression, atrophic gastritis or age, allows more undigested material to reach the small intestine and permits bacteria to survive the passage that should have killed them.
6. The hormonal pattern
Progesterone relaxes smooth muscle, including in the gut. In the luteal phase, transit slows, and bloating that tracks the menstrual cycle is a hormonal pattern rather than a dietary one. It is worth recognising because the dietary interventions that help the other causes do very little here.
Why does cutting out more foods stop working?
Almost everyone arrives having already removed things, usually in this order: gluten, dairy, onion and garlic, beans, cruciferous vegetables, then fruit.
This works at first and then stops. There are two reasons.
The first is that restriction treats the downstream event. If fermentation is producing symptoms because bacteria are in the wrong place, removing their fuel reduces the symptom while the overgrowth continues. Symptoms return as soon as the food does.
The second is that prolonged restriction reduces microbial diversity, which is itself associated with worse symptoms. The diet that relieves bloating in month one can be part of why it is harder to treat in month six.
A low FODMAP diet is a diagnostic instrument with a defined duration, usually four to six weeks, followed by structured reintroduction. It was never designed to be permanent, and the reintroduction phase is the part that gets skipped.
Which tests are worth doing?
Worth doing, depending on the pattern:
Breath testing for SIBO, where symptoms come within 90 minutes of eating
Coeliac serology, taken while still eating gluten. This has to come first, because the test is invalid once gluten is removed
Full blood count, ferritin, B12, folate, which flag malabsorption and quietly rule several things in or out
Thyroid function, because hypothyroidism slows transit
Stool testing for microbial composition and inflammatory markers, where the picture suggests dysbiosis or inflammation
Pelvic ultrasound and CA-125 in any woman with new, persistent bloating. See the red flags section
Not worth doing:
IgG food intolerance panels. IgG antibodies to food reflect exposure, not intolerance. Allergy societies advise against their use in this context. They generate long lists of foods to avoid, which is exactly the trap described above
Hair mineral analysis and live blood analysis, neither of which has validity for this question
What to change first
Before anything else, establish the timing. Photograph your abdomen morning and evening for a week, and note when the bloating starts in relation to meals. This single step directs everything that follows and costs nothing.
Then, in this order:
Fix evacuation before anything else. If stool is not clearing completely, nothing downstream works properly. This is the most common reason a good protocol fails
Slow down eating and remove the obvious air sources. Carbonated drinks, chewing gum, drinking through straws, eating while talking. This sounds trivial and resolves a meaningful minority of cases
Test before restricting. Coeliac serology first, while still eating gluten
If restriction is used, give it an end date. Four to six weeks, then structured reintroduction
Treat the cause the tests identify, rather than continuing to narrow the diet
Supplements worth considering
Dosage depends on the cause, so these are directional rather than prescriptive.
Peppermint oil, enteric coated. Antispasmodic with reasonable evidence in bloating and IBS. The enteric coating matters, as uncoated peppermint worsens reflux
Digestive enzymes. Useful where pancreatic output is genuinely reduced, and largely useless where it is not. Lactase specifically is worth it in confirmed lactose intolerance
Magnesium. Supports motility where constipation is part of the picture
Strain-specific probiotics. Helpful in some patterns and counterproductive in SIBO, where adding more bacteria to the small intestine is not obviously a good idea. Strain and timing decide this
Ginger. Modest evidence for improving gastric emptying, and low risk
Nothing on this list treats a cause. They manage a symptom while the cause is identified and addressed, which is a reasonable thing to do and a poor thing to do indefinitely.
Frequently asked questions
Is it normal to be bloated every day?
No. Occasional bloating after a large or unusual meal is normal physiology. Daily bloating that affects what you wear or how you feel is a symptom with a cause, and it is worth identifying rather than accommodating.
Why am I flat in the morning and bloated by evening?
Because the mechanism is cumulative. Gas accumulates through the day, transit slows, and in abdomino-phrenic dyssynergia the abdominal wall progressively gives way rather than containing the volume. A flat morning abdomen that distends through the day is the classic functional pattern, and it is more often a motility and muscular problem than a food one.
Can stress cause bloating?
Yes, through two routes. Stress slows gastric emptying and alters motility, and it increases visceral sensitivity, meaning normal gut signals are perceived as painful. This is why bloating often worsens in difficult periods without any change in diet.
Is bloating a sign of something serious?
In the large majority of cases, no. But new, persistent bloating, particularly in women over 50, needs investigation rather than a diet. See the red flags below. This is the part of bloating advice that gets left out, and it is the part that matters most.
Should I cut out gluten?
Not before testing. Coeliac serology is only valid while you are still eating gluten, so removing it first destroys your ability to get a clean answer and can delay a diagnosis by years. Test, then decide.
Do probiotics help with bloating?
Sometimes, and sometimes they make it worse. In SIBO, adding bacteria to a small intestine that already has too many is not reliably helpful. Strain, dose and timing determine the outcome, and a generic product chosen off a shelf is not the intervention the trials tested.
Why does bloating get worse before my period?
Progesterone rises in the luteal phase and relaxes smooth muscle throughout the body, including the gut. Transit slows, and gas and stool accumulate. A bloating pattern that tracks the cycle is hormonal, which is why dietary changes often make little difference to it.
How long does it take to improve?
If the cause is constipation or eating pace, days to a couple of weeks. SIBO treatment runs four to six weeks with a reasonable rate of recurrence. Abdomino-phrenic dyssynergia responds to breathing retraining over weeks to months. The honest answer depends entirely on which of these it is, which is the argument for establishing that first.
Can low stomach acid cause bloating?
Yes, and it is frequently mistaken for the opposite. Reduced acid allows bacteria to survive into the small intestine and leaves protein less well digested. People in this position are often prescribed acid suppression for the discomfort, which makes the underlying mechanism worse even as it relieves the sensation.
I have cut out everything and I am still bloated. What now?
Stop cutting things out and start testing. Persistent bloating despite extensive restriction usually means the mechanism is not dietary. Abdomino-phrenic dyssynergia, visceral hypersensitivity, pelvic floor dysfunction and untreated SIBO all behave this way. Further restriction at this point reduces diversity and makes the problem harder to treat.
When to seek medical investigation
⚠️ See a doctor rather than changing your diet if you have: Bloating is usually benign. These specific features are the ones that are not, and they are worth ruling out early rather than after six months of elimination diets.
New, persistent bloating, particularly if you are a woman over 50. Persistent bloating is one of the four symptoms in the ovarian cancer symptom index, alongside pelvic or abdominal pain, difficulty eating or feeling full quickly, and urinary urgency or frequency. Symptoms present on more than twelve days a month, for less than a year, warrant a pelvic ultrasound and CA-125. This is uncommon, and it is the reason bloating is never purely a dietary question
Unintentional weight loss
Blood in stool, or black tarry stools
Persistent vomiting, or difficulty swallowing
Anaemia, or iron deficiency without an obvious cause
A change in bowel habit lasting more than six weeks, if you are over 50
Severe pain, fever, or a hard and tender abdomen
A family history of ovarian, bowel or stomach cancer
How I work with bloating in practice
Most people arrive having already removed a great deal from their diet, with a list of trigger foods and no explanation. The work is usually the reverse of what they expect: establishing the pattern, testing what should be tested, treating the mechanism, and then putting food back.
In consultation that means taking a proper symptom timeline, checking evacuation honestly, arranging breath testing or coeliac serology where indicated, reviewing the medication history including acid suppression, and building a plan with an end date rather than an ever shortening list of safe foods.
Rita Soares is a functional medicine nutritionist based in Lisbon, Portugal, specialising in gut health, longevity and hormonal balance. Member of the Portuguese Order of Nutritionists (No. 2604N) and the Institute for Functional Medicine.
Scientific references
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