Most of us know the post-meal "I need to unbutton my pants" feeling. Far fewer people ever get a straight answer to the question "why do I feel bloated?" The honest answer is that there are a lot of possible reasons. Here's a guide to the common ones.
What is bloating, exactly?
Bloating is a feeling of fullness, pressure or swelling in your belly. Sometimes your abdomen visibly gets bigger, which doctors call distention, but only about half of people with bloating also have distention. That's because bloating is partly about sensation: how sensitive your gut is to normal amounts of gas and stool, not just how much is there. Researchers have long noted that bloating is hard to measure for exactly this reason.
Bloating is a symptom rather than a diagnosis, and it can feel very different depending on the cause.
Is it normal to feel bloated after eating?
Yes, within limits. Having some gas symptoms is normal, especially during or after meals. Gas comes from two main places: air you swallow while eating, drinking or chewing gum, and the gas your gut bacteria make when they ferment food you haven't fully digested.
Bloating is worth looking into when it happens often, bothers you or gets in the way of daily life.
Can food cause bloating?
Fermentable carbohydrates (FODMAPs)
Some carbohydrates are only partly absorbed in the small intestine, so they reach the large intestine, where bacteria ferment them and make gas. These are often called FODMAPs. Common examples include beans and lentils, cruciferous vegetables like broccoli and cauliflower, foods high in fructose or lactose, and sugar-free products sweetened with sugar alcohols (ingredients ending in "-ol").
FODMAP foods aren't bad for you; many feed beneficial gut bacteria, which is why they overlap with prebiotics. And this isn't an allergy: symptoms come from fermentation and water drawn into the gut, and how much you can tolerate varies from person to person.
Salt
Salty meals can leave you feeling puffy. In a large randomized feeding trial, higher sodium intake increased the risk of bloating regardless of the overall diet.
A sudden jump in fiber
The same trial found that a high-fiber diet also increased bloating. Fiber is still very good for you, so the fix is to increase it gradually and drink enough water, rather than avoid it.
If you suspect a particular food, a simple food and symptom diary can help you spot patterns. A registered dietitian can help you test it properly.
Can constipation cause bloating?
Yes. When stool moves slowly through your colon, it takes up room and gives bacteria more time to ferment it, so bloating and constipation often go together. Low fiber intake, not drinking enough, inactivity and some medications can all slow things down. Doctors may also check for a pelvic floor problem when bloating seems tied to constipation or difficulty passing stool.
What medical conditions cause bloating?
Irritable bowel syndrome (IBS)
Bloating is one of the most common IBS symptoms. In a U.S. survey of people with IBS, 82.5% reported bloating, and it ranked as the second most bothersome symptom after cramping. IBS is linked to problems with how the brain and gut work together, which can make the gut more sensitive to normal amounts of gas.
Small intestinal bacterial overgrowth (SIBO)
Most gut bacteria live in the large intestine. In SIBO, there are too many bacteria in the small intestine, where they ferment food early and can cause bloating, gas, pain and diarrhea. SIBO is diagnosed with a breath test and treated by a doctor, usually with antibiotics.
Lactose intolerance and celiac disease
Both can cause bloating, and both can be tested for. Doctors may use diet changes, breath tests or blood tests to rule them out. Our article on lactose intolerance and gut health explains the first.
Why do I feel bloated before my period?
Hormone shifts across the menstrual cycle affect how your body handles fluid. Estrogen and progesterone both influence fluid regulation, and in a year-long study of healthy women, self-reported fluid retention peaked on the first day of the period. So if your waistband feels tighter at that time of the month, you're not imagining it.
Can stress or your microbiome cause bloating?
The gut and brain are closely connected, and stress can make a sensitive gut more reactive. That's why psychological therapies such as gut-directed hypnotherapy and CBT are effective for IBS symptoms. Our article on chronic stress and gut health goes deeper.
Your gut microbes play a part too. You carry roughly as many bacterial cells as human cells, and they produce the gas from fermentation. Changes to your diet, antibiotics or starting a new probiotic can temporarily change how much gas you make. Some people notice extra gas in the first weeks of a probiotic; our guide to potential probiotic side effects explains why.
When should you see a doctor about bloating?
Talk to your doctor if bloating bothers you often, changes suddenly, or comes with abdominal pain, constipation, diarrhea or weight loss. Those can point to a condition that needs a proper diagnosis.
For everyday post-meal bloating, our guide to natural bloating remedies covers what helps. Because your gut bacteria are part of the picture, a daily probiotic can support digestive comfort too: Trust Your Gut combines 16 billion CFU from 6 acid-resistant strains with organic prebiotics to help support occasional bloating. And if large meals tend to leave you uncomfortably full, a digestive enzyme taken with food, such as Break It Down, may help support post-meal comfort.
