Fatty Liver: Causes, Symptoms, and Treatment Explained Simply

Fatty liver disease is one of the most common liver diseases in Western industrialized countries. In Germany, approximately 20–30% of the population is affected by a non-alcoholic form; among people with diabetes mellitus, estimates range up to 50%in some cases. Overall, steatosis accounts for about 10–20% of cases of liver cirrhosis and liver cancer. As obesity and metabolic disorders become more widespread, the risk of related complications—including cardiovascular complications—increases.

In Western countries, two main factors are decisive: excessive alcohol consumption and metabolic syndrome. The latter includes obesity, diabetes mellitus (type 2 diabetes), and elevated blood lipid levels—a combination of risk factors that can significantly increase the likelihood of developing fatty liver disease. When metabolism becomes unbalanced, fat is stored in the liver.

Alcohol – Guidelines:
The point at which alcoholic steatosis develops varies from person to person. As a rough upper limit, ≈ 10 g of alcohol per day for women and ≈ 20 g per day for men are generally considered safe. This corresponds to about 0.125–0.25 l of wine or 1–2 small beers (0.3 l).

Alcohol as the primary cause of liver damage such as fatty liver © Henrie | AdobeStock

Other medical conditions can also trigger or exacerbate fatty liver disease:

• Lipid metabolism disorders
• Celiac disease (gluten intolerance)
• Chronic viral hepatitis
• HIV infection
• Iron and copper storage disorders
• Gaucher disease
• Lifestyle & Medications

Additional risk factors include:

• Certain medications (e.g., cortisone, acetylsalicylic acid, tetracyclines, amiodarone, methotrexate)
• An unhealthy diet high in readily available carbohydrates
• Lack of exercise
• Stressful situations for the body (prolonged starvation, artificial feeding)

An unhealthy diet as a risk factor for the development of fatty liver © happy_lark | AdobeStock

• Pregnancy: Steatosis may occur during the final months of pregnancy; it is usually harmless. However, acute fatty liver of pregnancy requires close clinical monitoring.
• Genetic factors: Variants such as PNPLA3 can contribute to steatosis and influence its progression to liver fibrosis, cirrhosis, and liver cancer.

Classification of Terms:
Non-alcoholic forms are now often grouped under the umbrella term “steatotic liver diseases”—officially known as metabolic dysfunction-associated steatotic liver disease. If inflammation of the liver also develops, the condition is referred to as metabolic dysfunction-associated steatohepatitis. These various causes of fatty liver ultimately lead to fatty liver; if left untreated, the liver tissue can scar and progress to cirrhosis.

At first, there are often hardly any signs. As the liver becomes increasingly fatty, the organ may enlarge; symptoms then begin to appear, though they are nonspecific. A possible warning sign is a dull feeling of pressure or fullness.

Typical but non-specific symptoms (symptoms of fatty liver):

• Pain in the upper right abdomen or a feeling of pressure in the upper right abdomen
• Feeling of fullness, loss of appetite
• Nausea, occasional vomiting, bloating

If the fatty liver becomes inflamed (fatty liver hepatitis / steatohepatitis), additional signs may appear:

• Fever
• Yellowing of the skin and eyes (jaundice)

Jaundice indicates liver damage such as fatty liver © Daria | AdobeStock

About 30% of those affected show signs of steatohepatitis; among overweight individuals, the rate is as high as 50%. Complications of long-standing fatty liver disease can include cardiovascular diseases (e.g., atherosclerosis, high blood pressure, circulatory disorders)—thereby increasing the risk of serious secondary complications.

Diagnosis of fatty liver: The diagnosis is based on medical history, physical examination, blood tests (liver function tests), and ultrasound. Depending on the findings, elastography and, if necessary, a liver biopsy may follow. This allows for confirming the diagnosis of fatty liver, assessing the risk of steatohepatitis, and planning the next steps (“Diagnosis and Treatment”).

• Symptoms, pre-existing conditions, dietary habits, alcohol consumption.
• Palpation of the abdomen (liver size, tenderness).

Palpation of the right upper abdomen © pressmaster | AdobeStock

• Liver function tests: Gamma-GT, GOT (AST), GPT (ALT), alkaline phosphatase.
• Blood lipids: triglycerides, cholesterol (HDL/LDL).

Other values: Bilirubin, fasting blood glucose/HbA1c (screening for diabetes mellitus, including type 2 diabetes).
Important: Fatty liver cannot be diagnosed based on laboratory values alone; markers such as M30/M65 or adiponectin may indicate liver damage.

Evaluation of a laboratory blood test © Stockfotos-MG | AdobeStock

• Ultrasound (sonography) shows typical changes in brightness (“bright” liver), size, and structure.
• Elastography measures liver stiffness and helps identify stages of possible fibrosis; this allows for an assessment of whether tissue may already be scarring.
• In specific cases, MRI can provide additional information.

In cases of unclear findings or to determine the exact stage of the disease: removal of a small sample of liver tissue (under local anesthesia, using a hollow needle) and microscopic evaluation.

Liver biopsy © SciePro | AdobeStock

The PNPLA3 genetic marker can help assess risk (progression to liver fibrosis, cirrhosis, or liver cancer). The term metabolic dysfunction-associated steatotic liver disease (MASLD) is increasingly used in medical reports to describe steatotic forms. 

There is currently no specific drug therapy for fatty liver disease. Treatment aims to slow its progression and, if possible, reverse the fatty liver condition. Depending on the stage and cause (e.g., alcoholic fatty liver vs. non-alcoholic/MASLD—metabolic dysfunction-associated steatotic liver disease), lifestyle changes are the first line of treatment.

• Alcohol abstinence: In cases of alcoholic fatty liver disease, consistent abstinence is crucial.

Alcoholic fatty liver disease can resolve with alcohol abstinence © Pormezz | AdobeStock

• Weight Loss & Exercise: For overweight individuals (especially those with metabolic syndrome), a calorie-conscious diet and regular physical activity are helpful. This improves liver function tests and promotes fat breakdown in the liver. A sedentary lifestyle should be avoided.
• Dietary Changes: Adopt a healthy diet based on the Mediterranean diet (plenty of vegetables, legumes, fish, and olive oil) and reduce intake of rapidly absorbed carbohydrates and sugary beverages. Goal: to reduce excess fat in the liver.
• Manage underlying conditions: Properly control diabetes mellitus (including type 2 diabetes); treat lipid metabolism disorders (with cholesterol-lowering medications if necessary). Certain medications with the potential to cause liver damage should also be reviewed by a doctor.
• Non-alcoholic variants (MASLD): For steatotic liver disease with metabolic dysfunction, lifestyle therapy is the primary focus; if the liver becomes inflamed (steatohepatitis), close medical monitoring is advisable.
• Bariatric surgery: In cases of severe obesity where conservative measures have failed, bariatric surgery (e.g., gastric bypass, gastric band) may be considered.

• Ultrasound screenings: At least every six months in cases of liver cirrhosis for the early detection of liver cancer.
• Laboratory Tests: Regular monitoring of liver function tests and cardiometabolic parameters.
• Long-term benefits: Consistent lifestyle changes reduce the risk of cardiovascular disease; if fatty liver disease remains untreated, the risk of cirrhosis and hepatocellular carcinoma increases.

The overall outlook is good: If the underlying cause is consistently addressed (e.g., abstinence from alcohol, weight loss, better blood sugar control), fatty liver disease can often resolve—sometimes within 2–3 months. Fatty liver often goes unnoticed at first, which is why early evaluation is advisable.

Important for staging:

• Simple fatty liver disease can progress to an inflammatory form (steatohepatitis).
• If left untreated, the risk of it progressing to liver cirrhosis increases—with liver cancer as a possible consequence. In these late stages, the damage is no longer fully reversible.
• At the same time, comorbidities (e.g., cardiovascular diseases) also become more significant.

Good prognostic factors: early lifestyle changes, stable liver function tests, treatment of diabetes mellitus and lipid metabolism disorders, regular checkups (ultrasound/lab tests).

Adverse factors: advanced stages with fibrosis, continued alcohol consumption, severe obesity, or uncontrolled type 2 diabetes.