Bloating and the science behind it.

Feeling ‘fat’, swollen or too stuffed after a meal – what you are experiencing might be bloating. You know, that uncomfortable feeling of fullness and gas that happens after a big meal, eating a food you’re particularly sensitive to, or when you’re on your period – that’s bloating.

Everyone gets bloated from time to time. But for sure it’s no fun.

Here is what science says about bloating:

Bloating is caused by intestinal gas buildup, overeating, eating a certain food (fatty, dairy, and fiber-loaded), and visceral hypersensitivity. It is a feeling of distention and sometimes results in an enlargement of our abdomen. People suffering from Irritable Bowel Syndrome (IBS) and other Functional Gastrointestinal Disorders(FGIDs) commonly suffer from bloating.

One of the most common causes of bloating is the gas buildup in the gastrointestinal(GI) tract. Our GI tract is filled with many types of gases such as:

According to an article published in the British Medical Journal, “the gastrointestinal tract contains, on average, less than 200 mL of gas, whereas daily gas expulsion averages 600–700 mL.”

Collection of gases in the GI track higher than the average 200 mL may cause a feeling of distention and bloating.

The gases nitrogen and oxygen are most likely present through the air we swallow. On the other hand, carbon dioxide gas comes from swallowed air, carbonated drinks, diffusion from the bloodstream and reaction from the food we eat.
A research paper published in Gastroenterology also aimed to figure out the GI region most responsible for the retention of gas which causes the symptoms of bloating. It found that “In patients reporting bloating, the small bowel is the gut region responsible for ineffective gas propulsion.”


An overabundance of gases may also be formed in our colon if our diet contains an excess of ‘FODMAP’ carbohydrates(sugars). FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols.

FODMAP are carbohydrates that cannot be easily digested in our gut so they are instead fermented by our gut bacteria and the fermentation process creates gas such as hydrogen and methane in our gut.

According to an article published by John Hopkins Medicine, eating a diet consisting of FODMAPs may cause digestive distress for some people, including stomach bloating symptoms.

You can create a dietary diary and note the amount of your daily FODMAP consumption. You can also follow a FODMAP diet where you stop eating high FODMAP foods and slowly introduce FODMAP products one at a time to identify which ones are troublesome.

Sometimes, symptoms of bloating can occur without the actual change in the size of our GI tract. This is due to the reason that there are countless nerve fibers along and above our GI tract. Some people experience hypersensitivity in these GI tract nerves, and even a normal gastrointestinal process can exhibit symptoms of bloating.

This phenomenon is known as visceral hypersensitivity. A research paper published by the Journal of Neurogastroenterology and Motility(JNM) says that “The sensation of bloating may originate from abdominal viscera in patients with FGIDs, in whom normal stimuli or small variations of gas content within the gut may be perceived as bloating. Indeed, it has been well recognized that the patients with IBS have a lower visceral perception threshold than healthy controls,1,71 and it has been speculated that this process might be
associated with the sensation of bloating.”

There has been countless research done on the gastrointestinal causes and reasons for stomach bloating. A summary of the most notable research is as follow:

In this article, I will uncover the reasons behind the sensation of bloating–from certain food products to lifestyle habits to medical causes.

What causes bloating?

In the USA, 15-30% of the general population has been reported to experience bloating. One pilot study from Spain indicated that sugar intolerance was frequently observed in patients with bloating symptoms. Additionally, a sugar-free diet gave rise to clinical improvement in a high percentage of patients.

However, the causes of bloating aren’t clear-cut most of the time. Since bloating is a common symptom of gastrointestinal diseases like IBS, it can be hard to pinpoint the exact reasons behind it. Even lactose intolerance can cause bloating.

I will divide the causes of bloating into three sections; food, lifestyle, and medical factors.

1. Certain food products can cause bloating

Bloating can also be caused by what we eat. Some food products like sugar, fructose, and sorbitol are hard to break down by the microbes inside our stomach, so they can contribute to bloating.

Food products that may cause bloating are listed here:

● Beans, lentils, and other legumes

They contain FODMAPs, which we discussed before, may cause an excess buildup of gas and cause bloating.

● High sugar, fructose, sorbitol content food

Some people may suffer from fructose malabsorption, in which fructose is not effectively absorbed and might be fermented by gut bacteria and create excess gas.

● Carbonated and fizzy drinks

They contain high amounts of carbon dioxide gas which can cause gas buildup.

● Cabbage, brussels sprouts, turnips, beans, and lentils

They contain raffinose which is hard to break down inside our stomach.

● Chewing gums

The act of chewing gum can cause over swallowing of air into our GI tract.

● Dairy products

Experts estimate that about 68 percent of the world’s population has lactose malabsorption. People with lactose intolerance can experience bloating after consuming dairy products.

● Dairy products

Experts estimate that about 68 percent of the world’s population has lactose malabsorption. People with lactose intolerance can experience bloating after consuming dairy products.

● Eggs (if you have an allergy)

Gluten allergy can cause gas buildup in our bodies. Wheat also contains FODMAP carbohydrates.

● Wheat and gluten (if you have an allergy)

Experts estimate that about 68 percent of the world’s population has lactose malabsorption. People with lactose intolerance can experience bloating after consuming dairy products.

● Beer

○ Beer contains a high amount of carbon dioxide gas as well as fermentable carbs, which can cause the buildup of gas. The term ‘beer belly’ also refers to the bloating of the stomach as well as the increase in body fat.

2. Lifestyle habits that contribute to bloating

Sometimes, our lifestyle habits and behaviors can also unintentionally contribute to a case of bloating. As with most other diseases, a minimal exercise lifestyle certainly doesn’t help prevent bloating.

Some lifestyle habits which contribute to bloating are:

• Overeating in a short period
• Swallowing excessive air
• Sedentary lifestyle
• Rapid weight fluctuation due to inconsistent diet
• Using a straw for drinks
• Smoking
• Excessive drinking
• Sleeping immediately after eating
• Unbalanced diet
• Minimal exercise

3. Medical causes of bloating

As I briefly touched on before, figuring out the exact cause of bloating can be difficult as many diseases can include bloating as a symptom. Sometimes tackling the primary disease can cure bloating, while at other times, bloating can be a separate disease itself.

If you want to know the medical causes of bloating, then I have compiled a detailed list here:

● Acid reflux (GERD)
● Irritable Bowel Syndrome (IBS)
● other Functional Gastrointestinal Disorders(FGIDs)
● Small Intestinal Bacteria Overgrowth(SIBO)
● Lactose Intolerance
● Hormonal effects
● Anorexia or bulimia
● Psychological causes like stress, anxiousness, depression, etc
● Infection
● Inflammation
● Constipation
● Pelvic Inflammatory Disease
● Menstruation
● Celiac Disease
● Diabetes

If you are also interested in knowing how to get rid of bloating fast then we also have an article that goes in-depth into the remedies. We explore all the common remedies, from herbal and ayurvedic to over-the-counter medicines, that you can use to relieve yourself of bloating.

When to see a doctor

Bloating is a common occurrence, and we might take this intestinal discomfort for granted, but sometimes, it can also be a sign of a severe condition that requires medical attention. Consult your doctor if you experience the following along with bloating:

● severe abdominal pain
● blood in the stools
● excessively high fevers
● worsening heartburn
● unexplained weight loss

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