What causes a bloated stomach?

Are your jeans feeling tighter around your middle?

PMS, stress, food intolerances... there are a multitude of causes for a bloated stomach.

Here we explore some of the reasons for bloating and why what you’re eating might be making it worse.

Why am I constantly bloated?

“I’m so bloated,” is a phrase we’ve all said after a big meal sparks that familiar feeling of fullness.

But over-indulgence is just one of many causes of a bloated stomach. So, what else is your gut telling you when it starts to bulge?

Can stress cause stomach pain and bloating? Why do you get a bloated belly after eating?

The first step towards remedying the feeling of being uncomfortably full is to understand what makes it happen. Here we explore, what causes a bloated stomach?

What is a bloated stomach?

Bloating is the sensation caused when your stomach fills with gas.

When your tummy feels blown out and the waistbands of clothing suddenly get tighter.^1,2

For some people, bloating is only a sensation. For others, it’s accompanied by a physical expansion of the stomach area (officially known as abdominal distension.)³

Summary

• Bloating refers to the feeling of a tight, full or swollen abdomen 
• It’s usually a sensation caused by gas trapped in the gastrointestinal tract
• Some people also experience a physical abdominal distension

9 bloating symptoms

Symptoms of bloating include:⁴

1. Stomach pain. Trapped wind may cause crampy tummy pains.⁵ 
2. Tummy feels stretched and full. Increased pressure in the abdomen creates a sensation of bloating. Your tummy may also feel hard or tight. 
3. Constipation. Being unable to regularly empty your bowels can put pressure on the space in your gut.⁶
4. Sensation of excessive gas in the abdomen. Probably down to an accumulation of gas somewhere in your gastrointestinal tract. 
5. Flatulence. Once excess air travels down into your oesophagus, where does it go next? Frequently passing wind is one way gas is released.
6. Burping or belching. Another way excess air is excreted.
7. Nausea. Stomach bloating and nausea often happen at the same time.
8. Tummy looks bigger. The sensation of bloating is sometimes accompanied by a physical increase in the diameter of the abdomen.⁷
9. Stomach gurgling and rumbling. Caused by the movement of gas and fluids in the intestines.⁸

Summary

• Bloating happens when your GI tract fills with gas
• This leads to a variety of symptoms
• Common signs of bloating are feeling stretched, the sensation of feeling full, passing wind, burping and stomachache

What causes a bloated stomach?

When you have a disproportionate amount of gas lurking in your gut for some reason, your body may struggle to excrete this excess air.

If your digestive system is sensitive to these changes, bloating is a side effect.

What causes wind in the stomach?

We all carry a certain amount of gas in our digestive system.

Chewing food, gulping down a drink and talking can all cause you to swallow air. Certain activities can further elevate this – such as chewing gum, drinking fizzy drinks and smoking.⁹

In addition, sometimes your body produces more than normal amounts of gas. This happens for various reasons and contributes to feeling bloated.

9 causes of bloating

1. Your body’s sensitivity to gas. Some people are more prone to bloating in reaction to even normal amounts of gas in the abdomen.
2. Swallowing too much air. Formally known as aerophagia. You may do it subconsciously when you’re feeling stressed and it can be exacerbated by smoking and chewing gum.
3. Diet. Certain foods, such as Brussels sprouts and broccoli, are famed for causing excess gas.
4. Lactose intolerance. If your body finds it difficult to digest dairy products, you may find yourself prone to bloating.
5. Intolerance to fructose. Belly bloat is a common reaction to sensitivity to foods high in fructose, such as dried fruit and honey.
6. Coeliac disease. People who are intolerant to gluten can experience bloating after eating wheat, barley and rye.
7. Digestive conditions. For example, with irritable bowel syndrome (IBS), spells of tummy pain are often accompanied by bloating as well as changes in bowel habits.
8. Acute gastroenteritis. A tummy bug can sometimes cause an imbalance in gut flora that can lead to bloating. 
9. Medication. For example, a bloated tummy is a common unwanted side effect of laxatives and some antacids.^10,11

Why do some people experience a painful bloated stomach?

Having a constantly bloated stomach doesn’t necessarily mean you’re producing more gas than usual.

And it’s not always a symptom of an underlying condition. In some people, it’s simply an overreaction to normal amounts of gas in the abdomen.

And unfortunately, the reasons why this happens to some individuals and not others aren’t fully understood.¹²

Summary

• A certain amount of gas lurks in our guts
• Some people experience bloating due to an increase in gas, which can happen for a number of reasons
• Certain foods, digestive conditions and food intolerances are among the most common causes of bloating
• Certain people find they are sensitive to even normal amounts of gas 

Bloated stomach after eating

The festive period is a common time to experience bloating, for obvious gluttonous reasons.

However, what you eat, as well as how much, can be equally to blame for your bloated belly.

For example, food intolerances can stimulate bacteria breakdown that produces gas and inflammation of the gut.

12 foods that cause a bloated belly

1. Wheat. If you’re sensitive to gluten, bread, pizza, cakes and biscuits can be a trigger for bloating.
2. Cruciferous vegetables. Broccoli, cabbage and Brussels sprouts are known for being particularly gassy vegetables.
3. Beans. Legumes like lentils and chickpeas are fermented by gut bacteria in the colon. The process can produce excess gas
4. Fibre. High fibre foods, such as beans, fruit and peas, absorb water in the gut causing bloating.
5. Onions and garlic. They’re both rich sources of fructans. These are complex sugars that your small intestine struggles to break down.
6. Dried fruit. If your body has difficulty absorbing natural sugars, they may give you a bloating feeling.
7. Salt. A diet that’s high in sodium can cause water retention, which adds to feelings of fullness.
8. Fatty foods. Foods that are high in fat take longer to digest, slowing down stomach emptying and adding to bloating.
9. Alcohol. Drinking too much can delay stomach emptying and cause your stomach to bloat.
10. Carbonated drinks. The gassy fizz introduces extra air into your digestive system.
11. Some artificial sweeteners. They’re sweet-tasting, but they’re not easy for your body to digest.
12. Dairy foods. If you have a sensitivity to lactose you may find your waist expands after eating more than your gut can tolerate.^13,14

Summary

• There are a number of food groups that can contribute to bloating
• Dairy, wheat-based foods, some sugars, salt, fizzy drinks, beans and cruciferous vegetables are common culprits
• These are foods that your body finds more difficult to digest or that produce gas as they’re broken down in your gut

Menstrual cycle & bloating

Does your stomach feel bloated around the time of your period? Oestrogen has a big role in deciding how women retain water.

Levels of this hormone fluctuate during a woman’s monthly cycle, with the body typically retaining more water when oestrogen is higher in the week or so leading up to the start of a period.

As a result, a common symptom of premenstrual syndrome (PMS) is bloating.

Bloating and fatigue

Bloating and fatigue both have a whole range of causes and triggers. Sometimes making changes to your diet can help.

If bloating and tiredness persist, it’s worth chatting to your doctor to see if an underlying condition may be triggering your symptoms.

Food intolerances and allergies

If your body has difficulty digesting food, your bowel may not empty properly. This sometimes leads to the production of too much gas and this excess air may get trapped.¹⁵

Foods that are more likely to cause problems are:

• FODMAPS (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols.) Our bodies can find it hard work to digest the sugars in this group of foods (including wheat, onions, garlic and beans.) This leaves some of us with more gas in our digestive system.
• Wheat. If you’re sensitive to gluten or have problems digesting it, foods containing wheat can cause a painful bloated stomach.
• Dairy. If you don’t have a sufficient supply of the enzyme to break down lactose in your gut, eating dairy foods can cause a bloated belly.

Digestive conditions

Bloating is a symptom of a number of chronic diseases, including:

• Irritable bowel syndrome (IBS). The NHS suggests that ‘erratic propulsion of contents through the bowel’ may cause bloating in people with IBS.
• Coeliac disease. If your intestine can’t absorb gluten found in wheat, barley and rye it can trigger all kinds of digestive discomfort.
• Colitis and Crohn’s disease. These are conditions caused by inflammation of the gut wall. Gas-related symptoms, such as bloating, can often develop as a result.

Can stress cause bloating?

As we learn more about the gut-brain axis, it’s plausible that there’s a link between stress and bloating.

For example, in some people, anxiety and angst can lead to sluggish gut function, making digestive discomfort, such as belly bloat, worse.¹⁶

Is your bloated belly a sign of something else?

Tummy bloating is usually a harmless annoyance we experience from time to time. And the good news is, it’s usually short-lived.

For example, if it’s caused by your gut’s intolerance for gluten, removing wheat from your meals can often put a stop to bloating and gas after eating.

If your stomach is always bloated or it’s accompanied with other symptoms, it’s worth seeking guidance from your GP.

Conclusion: Why is my stomach bloated?

In simple terms, it’s down to some kind of imbalance in your gut.

But the reality is, what causes bloating for you personally could be any number of things. Maybe the expansion around your middle was set off by what you ate for your last meal?

Or it could be down to changes in your hormones? Perhaps it’s excess air intake due to over-zealous gum chewing or downing a fizzy drink?

If you want to find out what causes bloating in the stomach for you, the secret is recognising any patterns in the swelling around your waist.

So, the old adage ‘listen to your gut’, is literal logic when it comes to working out your reasons for bloating.

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Last updated: 24 August 2021