What causes bloating?
Bloating comes from gas, and gas gets into your digestive tract two ways: you swallow air, and bacteria in your large intestine break down carbohydrates that weren't digested higher up. [1] What decides whether you feel it is how much air you swallow, which foods you eat, whether you have one of a handful of common conditions, and how sensitive your gut is to a normal amount of gas. [1]
Bloating versus distention: which do you have?
The National Institute of Diabetes and Digestive and Kidney Diseases separates the two. Bloating is a feeling of fullness or swelling in the abdomen; distention is the abdomen actually becoming larger than usual. [1] Only about half of people with bloating also have distention, and some people feel more severe gas symptoms even when a normal amount of gas is in the digestive tract. [1] That matters because "I feel huge" and "my waistband is tighter" can have different explanations, and a clinician will ask which it is.
Cause one: swallowed air
People typically belch up to 30 times a day, and some belch more because they swallow too much air and release it before it reaches the stomach. [1] The habits the NIH names are chewing gum, sucking hard candy, drinking fizzy drinks, drinking through a straw, and eating on the run rather than slowly and sitting down. [2] This is the easiest cause to test: change the habits for a few days and see what happens.
Cause two: the foods you eat
Bacteria produce gas when they break down carbohydrates the small intestine didn't absorb. The NIH's list of foods and drinks that commonly increase gas: vegetables, especially cruciferous ones such as broccoli, cauliflower, collard greens and kale; legumes such as beans, peas and lentils; and candy, gum or other products containing sweeteners ending in "-ol" (sorbitol, mannitol, xylitol, erythritol, maltitol). [2] Some people have more gas symptoms when they consume too much fiber, especially when they add it quickly, and others when they eat high-fat foods, which can increase bloating. [2] None of these foods is bad; several are the ones a dietitian would want you eating more of. The point is to find your own threshold, which is why the NIH suggests a diary of what you eat and drink alongside your symptoms. [2]
Cause three: a condition that needs a name
The NIH lists several conditions that cause more gas or more gas symptoms. Functional gut disorders, which are problems with how the brain and gut work together, include irritable bowel syndrome, functional bloating and distention, functional constipation and functional dyspepsia. [1] Problems digesting certain carbohydrates include lactose intolerance and dietary fructose intolerance, which cause bloating, pain and diarrhea after the relevant foods. [1] Small intestinal bacterial overgrowth is an increase or change in the bacteria of the small intestine, produces extra gas and can also cause diarrhea and weight loss; the NIH describes it as most often a complication of another condition. [1] Other digestive conditions on the list include celiac disease, constipation, reflux and gastroparesis. [1]
Two of these are notably common in women. About 12% of people in the United States have IBS, women are up to two times more likely than men to develop it, and it is more common under 50 than over. [3] Constipation affects about 16 in 100 US adults, about 33 in 100 at age 60 and over, and is more likely in women and in older adults. [4] For IBS, a doctor may suggest eating more fiber, avoiding gluten, or following a low FODMAP diet; these are diagnosis-specific and worth doing with a professional rather than from a list online. [6]
Does perimenopause cause bloating?
It is one of the most common things women in their 40s ask, and the straight answer is that the evidence does not support it as a cause. The NIH's guidance on gas and bloating does not list menopause or hormones among the causes. [1] And the idea that menopause reshapes the gut's bacteria is, so far, unproven: a 2026 meta-analysis of seven studies covering more than 1,700 women found no consistent differences in microbiome diversity or major bacterial groups between post-menopausal and pre-menopausal women, with high variability between studies. [5] Bloating in your 40s and 50s most often has one of the ordinary causes above, and treating it as "just hormones" risks missing something that has a name and a fix.
What to bring to the appointment
A week's diary of food, drink and symptoms, which is the tool the NIH says helps a doctor or dietitian find food triggers. [2] Whether your belly visibly swells or only feels full. [1] How often you go, and whether that has changed. [4] And any pain, diarrhea or weight change, which move this from a diet question to a medical one. [1]
When to talk to your clinician
The NIH says to talk with your doctor if gas symptoms bother you, if they change suddenly, or if you have abdominal pain, constipation, diarrhea or weight loss along with them. [1] Bloating alone is rarely dangerous; bloating with those companions is a reason to be seen.
Sources
- NIDDK, Symptoms and causes of gas in the digestive tract. Last reviewed June 2021. Retrieved 2026-10-18.
- NIDDK, Eating, diet and nutrition for gas in the digestive tract. Last reviewed June 2021. Retrieved 2026-10-18.
- NIDDK, Definition and facts for irritable bowel syndrome. Last reviewed November 2017. Retrieved 2026-10-18.
- NIDDK, Definition and facts for constipation. Last reviewed May 2018. Retrieved 2026-10-18.
- Saravinovska K et al. The impact of estrogen status on the gut microbiome: a systematic review and meta-analysis. Frontiers in Endocrinology, 2026;17:1780806. Abstract retrieved 2026-10-18.
- NIDDK, Eating, diet and nutrition for irritable bowel syndrome. Retrieved 2026-10-18.
Every statement above was checked against the linked source on October 18, 2026. This article is education, not individual medical advice. Related: How to reduce bloating quickly · How to improve gut health.