Fatty liver disease frequently causes no symptoms, particularly when it is in an early stage. This is one reason hepatic steatosis is often discovered incidentally during blood tests or abdominal imaging undertaken for another reason. A person can have substantial amounts of liver fat without experiencing characteristic pain, digestive symptoms or visible physical changes. The absence of symptoms therefore cannot reliably distinguish mild disease from disease that warrants further assessment. NIDDK describes metabolic fatty liver disease as usually being silent, with few or no symptoms, and the NHS similarly states that non-alcoholic fatty liver disease does not usually cause symptoms.
When symptoms do occur, one recognised symptom is persistent tiredness or fatigue. Fatigue is non-specific, meaning that it can result from numerous conditions and cannot by itself establish fatty liver disease. People may also describe a general feeling of being unwell. These symptoms can occur with many metabolic, inflammatory, infectious and systemic disorders, so clinicians do not diagnose fatty liver on the basis of tiredness alone. Instead, fatigue may prompt medical evaluation in which liver blood tests or imaging reveal an otherwise unsuspected liver abnormality.
Another possible symptom is discomfort or pain in the upper right part of the abdomen, beneath the right side of the rib cage where the liver is located. The discomfort may relate to enlargement or stretching of the liver capsule rather than the fat itself directly producing pain. However, right-upper-abdominal discomfort has many possible causes, including gallbladder disease, gastrointestinal disorders and musculoskeletal problems, so its presence is not specific to fatty liver. The NHS describes liver pain or discomfort under the right ribs as a possible symptom, while NIDDK similarly notes discomfort in the upper right abdomen in people who have symptoms.
More obvious symptoms generally raise concern that liver disease has progressed beyond uncomplicated steatosis, particularly if fibrosis or cirrhosis has developed. Advanced liver disease can cause jaundice, in which the skin and whites of the eyes become yellow; itching; loss of appetite; unintended weight loss; nausea; marked weakness or fatigue; abdominal swelling from ascites; leg swelling; dark urine; and other manifestations of impaired liver function or portal hypertension. These findings are not typical indicators of uncomplicated fatty liver and should not be interpreted as evidence that every person with steatosis will progress to cirrhosis.
The lack of symptoms creates an important diagnostic distinction between subjective symptoms and objective liver injury. Liver enzymes such as ALT and AST can be abnormal in fatty liver disease, but they can also be normal despite clinically relevant disease, so normal blood tests do not necessarily exclude hepatic steatosis or significant fibrosis. Conversely, elevated liver enzymes have many causes and do not prove fatty liver. Doctors therefore combine symptoms and history with blood tests, imaging and, when appropriate, non-invasive fibrosis assessment or biopsy. Ultrasound may reveal hepatic steatosis, while elastography can help assess liver stiffness and the probability of fibrosis.
Symptoms can also be influenced by associated metabolic conditions rather than by liver fat itself. Someone with MASLD may simultaneously have obesity, type 2 diabetes, hypertension, sleep-related disorders, cardiovascular disease or dyslipidaemia, each of which can produce symptoms or health consequences. This makes it difficult to attribute fatigue, reduced exercise tolerance or general malaise specifically to the liver without assessment. The clinical significance of fatty liver is consequently determined not merely by how a person feels but by the cause of steatosis, the extent of fibrosis and the presence of associated metabolic and liver disease.
Fatty liver can sometimes be identified before symptoms appear through investigations performed for other reasons. A routine blood test may reveal unexpectedly abnormal liver enzymes, and an ultrasound performed for abdominal symptoms may show increased liver echogenicity consistent with steatosis. Clinicians then investigate alcohol intake, weight, diabetes, lipid levels, medicines and other potential causes. If fatty liver is found incidentally, it should not automatically be dismissed as harmless, but neither does the finding mean that cirrhosis is present. Further assessment is used to determine whether the liver has inflammation or fibrosis and whether potentially reversible risk factors can be addressed.
The most important practical point about symptoms is that fatty liver disease can remain clinically silent while still warranting assessment. Persistent unexplained fatigue, right-upper-abdominal discomfort, abnormal liver tests, jaundice or other signs of liver disease should be discussed with a healthcare professional, particularly when metabolic risk factors or substantial alcohol exposure are present. Jaundice, significant abdominal swelling, vomiting blood, black stools, confusion or other signs suggestive of advanced liver disease require prompt medical assessment rather than self-diagnosis. Symptoms alone cannot determine whether steatosis is simple, inflammatory or fibrotic; determining the underlying cause and degree of liver damage is more informative.
