Does fatty liver cause smelly farts? This common question reflects growing awareness of non-alcoholic fatty liver disease (NAFLD), which affects approximately one in three UK adults. Whilst fatty liver disease can influence various aspects of metabolism, there is no established direct link between hepatic steatosis and malodorous flatulence. Most digestive symptoms in people with fatty liver arise from dietary patterns, concurrent conditions such as irritable bowel syndrome, or metabolic factors rather than liver pathology itself. Understanding the true causes of excessive wind helps distinguish normal digestive processes from symptoms requiring medical attention.

Understanding Fatty Liver Disease and Digestive Symptoms

Fatty liver disease, medically termed hepatic steatosis, occurs when excess fat accumulates in liver cells. In the UK, non-alcoholic fatty liver disease (NAFLD) affects approximately one in three adults, making it the most common liver condition nationwide (NHS). The condition exists on a spectrum, ranging from simple steatosis (fat accumulation without inflammation) to non-alcoholic steatohepatitis (NASH), which involves inflammation and potential scarring. Some organisations now use the term metabolic dysfunction-associated steatotic liver disease (MASLD) to reflect the underlying metabolic drivers.

Most individuals with fatty liver disease have no symptoms in the early stages, which is why it is often discovered incidentally during routine blood tests or abdominal imaging. When symptoms do occur, they typically include:

• Persistent fatigue and general malaise

• Discomfort or dull aching in the upper right abdomen

• Unexplained weight changes

• General feelings of being unwell

Digestive symptoms such as bloating, changes in bowel habits, and increased flatulence are commonly reported by people with fatty liver disease, though these are usually related to associated conditions rather than the fatty liver itself. Metabolic syndrome—a cluster of conditions including obesity, type 2 diabetes, high blood pressure, and abnormal cholesterol levels—frequently coexists with NAFLD and can independently affect digestive function. Dietary patterns, irritable bowel syndrome (IBS), and small intestinal bacterial overgrowth (SIBO) are often the true culprits behind digestive discomfort in this population.

The liver plays a crucial role in digestion by producing bile, which helps break down dietary fats. In uncomplicated fatty liver disease, bile production is typically maintained. However, in advanced liver disease or cholestasis (impaired bile flow), bile composition may be altered, potentially contributing to fat malabsorption and digestive disturbances. Understanding this distinction helps patients and healthcare professionals recognise that most digestive symptoms in early NAFLD arise from diet, lifestyle, or concurrent conditions rather than liver pathology itself.

Can Fatty Liver Cause Smelly Farts?

There is no established direct link between fatty liver disease and malodorous flatulence in medical literature. Whilst fatty liver can affect various aspects of metabolism, the production of smelly wind is primarily determined by bacterial fermentation in the large intestine rather than liver pathology. The characteristic odour of flatulence results from sulphur-containing compounds produced when gut bacteria break down certain foods and proteins.

However, several indirect connections may explain why people with fatty liver disease report increased or more odorous flatulence:

Dietary patterns: The same dietary habits that contribute to fatty liver development—high intake of processed foods, refined carbohydrates, and saturated fats—can also promote digestive symptoms. Diets low in fibre and high in fat may slow digestion and alter gut bacteria populations, leading to increased flatulence. Excessive intake of fructose from sweetened beverages and processed foods is associated with increases in liver fat and may also affect gut fermentation.

Small intestinal bacterial overgrowth (SIBO): Some observational research suggests that people with NAFLD may have higher rates of SIBO, a condition where excessive bacteria colonise the small intestine. SIBO commonly causes bloating, excessive wind, and changes in stool consistency. The mechanisms linking fatty liver to SIBO remain under investigation but may involve altered gut motility and changes in the gut-liver axis. If you experience chronic diarrhoea or persistent bloating, your GP may consider testing for SIBO or bile acid malabsorption as part of a comprehensive assessment.

Metabolic factors: Insulin resistance and diabetes, which frequently accompany fatty liver disease, can affect gut motility and the composition of intestinal bacteria, potentially contributing to increased gas production.

Important distinction: If you notice pale, greasy stools that float (steatorrhoea), this suggests fat malabsorption, which is more typical of bile acid malabsorption, cholestasis, pancreatic exocrine insufficiency, or advanced liver disease rather than simple fatty liver. This symptom warrants medical assessment.

Common Causes of Excessive Wind and Odour

Understanding the typical causes of malodorous flatulence helps distinguish normal digestive processes from potential health concerns. Most flatulence is entirely normal, with the average person passing wind 5–15 times daily (NHS). The odour and volume depend largely on diet, gut bacteria composition, and digestive efficiency.

Dietary factors represent the most common cause of smelly flatulence:

• Sulphur-rich foods: Cruciferous vegetables (broccoli, cauliflower, Brussels sprouts, cabbage), onions, garlic, and eggs contain sulphur compounds that produce characteristic odours when broken down by gut bacteria

• High-protein foods: Red meat and certain dairy products can increase sulphur-containing gas production

• Fermentable carbohydrates: Beans, lentils, and certain grains contain oligosaccharides that humans cannot fully digest, leading to bacterial fermentation and gas production

• Artificial sweeteners: Sorbitol, xylitol, and other sugar alcohols found in sugar-free products can cause excessive wind and loose stools

Digestive conditions that commonly cause increased or malodorous flatulence include:

Lactose intolerance affects approximately 5% of people of Northern European descent and higher percentages in other ethnic groups. Inability to digest lactose leads to bacterial fermentation in the colon, producing excessive, often foul-smelling gas alongside bloating, cramping, and diarrhoea.

Irritable bowel syndrome (IBS) affects 10–20% of UK adults and frequently causes bloating, altered bowel habits, and increased flatulence (NICE CG61). The condition involves altered gut-brain communication and changes in intestinal bacteria. Dietary modification under the guidance of a registered dietitian, including a low-FODMAP approach, may help identify trigger foods.

Coeliac disease, affecting about 1% of the UK population, causes malabsorption when gluten is consumed, leading to various digestive symptoms including excessive wind (NICE NG20). Many cases remain undiagnosed. If coeliac disease is suspected, testing should include tissue transglutaminase IgA (tTG-IgA) and total IgA whilst you continue eating gluten.

Bile acid malabsorption (BAM) can cause chronic diarrhoea, urgency, and excessive wind. It may be considered if symptoms persist despite dietary changes.

Medications can also contribute to flatulence. Metformin (commonly prescribed for type 2 diabetes), orlistat (weight management), acarbose (diabetes), antibiotics, and certain supplements may alter gut bacteria or affect digestion, increasing gas production. If you suspect a medicine is causing digestive symptoms, discuss this with your GP or pharmacist—do not stop prescribed medicines without medical advice. You can report suspected side effects via the MHRA Yellow Card Scheme at yellowcard.mhra.gov.uk.

When Digestive Symptoms May Signal Liver Problems

Whilst isolated flatulence rarely indicates serious liver disease, certain combinations of symptoms warrant medical evaluation. Advanced liver disease can present with digestive symptoms alongside other warning signs that require prompt assessment.

Red flag symptoms that should prompt urgent GP consultation or emergency care include:

• Jaundice: Yellowing of the skin or whites of the eyes indicates significant liver dysfunction and requires immediate medical attention. If accompanied by fever, severe abdominal pain, or confusion, seek emergency care (999 or A&E)

• Vomiting blood or passing black, tarry stools: These suggest gastrointestinal bleeding and require emergency assessment

• Ascites: Abdominal swelling due to fluid accumulation, often accompanied by rapid weight gain and ankle swelling

• Dark urine and pale stools: Changes in urine colour (tea-coloured) or stool appearance (clay-coloured or very pale) suggest bile flow problems

• Persistent nausea and vomiting: Especially when accompanied by loss of appetite and unintentional weight loss

• Severe or persistent abdominal pain: Particularly in the upper right abdomen, which may indicate liver inflammation or complications

• Marked confusion or drowsiness: May suggest hepatic encephalopathy in advanced liver disease and requires urgent assessment

Digestive symptoms warranting investigation when occurring with known or suspected fatty liver disease:

Chronic diarrhoea (lasting more than four weeks) or steatorrhoea (pale, greasy, foul-smelling stools that float) may indicate bile acid malabsorption, pancreatic exocrine insufficiency, or cholestasis rather than simple fatty liver. Your GP can arrange appropriate investigations.

Change in bowel habit with other features: According to NICE guidance (NG12, DG30), if you are aged 60 or over with a change in bowel habit, or if you have unexplained iron-deficiency anaemia, rectal bleeding, or abdominal mass, your GP may arrange a faecal immunochemical test (FIT) and consider urgent referral to rule out colorectal cancer. Persistent symptoms warrant assessment regardless of age.

Severe bloating with early satiety (feeling full quickly) combined with unintentional weight loss should be investigated to rule out complications or concurrent conditions.

Monitoring fatty liver disease: NICE guidance (NG49) recommends that individuals with risk factors for fatty liver disease—including obesity, type 2 diabetes, high cholesterol, or metabolic syndrome—undergo regular monitoring. Blood tests (liver function tests or LFTs) are commonly used, but normal LFTs do not exclude significant liver disease. For adults with confirmed NAFLD, the Enhanced Liver Fibrosis (ELF) blood test is recommended to assess the risk of advanced fibrosis. In some areas, transient elastography (FibroScan) may also be used. Your GP will arrange appropriate monitoring and refer you to a hepatology specialist if advanced fibrosis or cirrhosis is suspected.

Managing Flatulence and Supporting Liver Health

Lifestyle modifications form the cornerstone of managing both fatty liver disease and digestive symptoms. Evidence-based approaches recommended by NICE (NG49) and the British Society of Gastroenterology focus on addressing underlying metabolic factors whilst improving digestive comfort.

Dietary strategies for reducing flatulence:

• Keep a food diary: Identify specific triggers by recording foods consumed and subsequent symptoms. Common culprits include dairy, wheat, certain vegetables, and artificial sweeteners

• Eat slowly and mindfully: Rushing meals causes air swallowing (aerophagia), which contributes to bloating and flatulence

• Reduce portion sizes: Smaller, more frequent meals may improve digestion and reduce gas production

• Limit carbonated beverages: These introduce additional gas into the digestive system

• Consider a low-FODMAP approach: Under the guidance of a registered dietitian, temporarily reducing fermentable carbohydrates may help identify problematic foods (NICE CG61). This should not be undertaken without professional supervision

Supporting liver health through lifestyle:

Weight management represents the most effective intervention for fatty liver disease. NICE (NG49) recommends a target weight loss of 7–10% of body weight for individuals with NAFLD, which can significantly reduce liver fat and inflammation. Gradual weight loss (0.5–1 kg per week) is safer and more sustainable than rapid reduction.

Physical activity benefits both liver health and digestive function. The NHS recommends at least 150 minutes of moderate-intensity aerobic activity weekly (such as brisk walking or cycling), plus strength training on two or more days per week. Exercise improves insulin sensitivity, reduces liver fat, and promotes healthy gut motility.

Dietary patterns for liver health:

• Mediterranean-style diet: Rich in vegetables, fruits, whole grains, legumes, nuts, and olive oil, with moderate fish consumption and limited red meat

• Reduce added sugars: Particularly fructose from sweetened beverages and processed foods, which is associated with increases in liver fat accumulation

• Increase fibre intake: Supports healthy gut bacteria and improves metabolic health

• Limit alcohol: The UK Chief Medical Officers advise that if you have fatty liver disease, it is safest not to drink alcohol regularly. If you choose to drink, keep within the low-risk guidelines (no more than 14 units per week, spread over three or more days, with several alcohol-free days). If you have NASH, fibrosis, or cirrhosis, abstinence is essential or as advised by your specialist

Medication review: If you are taking medicines that may cause digestive symptoms (such as metformin, orlistat, or antibiotics), discuss this with your GP or pharmacist. Do not stop prescribed medicines without medical advice. Report suspected side effects via the MHRA Yellow Card Scheme at yellowcard.mhra.gov.uk.

When to seek professional help: Consult your GP if flatulence is accompanied by pain, persistent bloating, changes in bowel habits lasting more than four weeks, unexplained weight loss, or if you have concerns about liver health. Blood tests can assess liver function and fibrosis risk (ELF test), and referral to gastroenterology or hepatology services may be appropriate for comprehensive evaluation and management of both digestive symptoms and fatty liver disease.

Frequently Asked Questions