In 2023, a global panel of medical experts renamed Non-Alcoholic Fatty Liver Disease (NAFLD) to Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD). This change was made to remove potentially stigmatizing language and to more accurately describe the condition’s strong connection to overall metabolic health. The new name helps clarify that the disease is not simply about the absence of alcohol but is driven by a cluster of metabolic issues. The introduction of this updated terminology aims to improve patient awareness and direct research toward the metabolic origins of the disease.
Defining METALD and Its Risk Factors
The diagnosis of Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) is based on two core components: the presence of excess fat in the liver, a condition known as hepatic steatosis, combined with at least one of five specific cardiometabolic risk factors. This new diagnostic framework moves away from the old model, which primarily focused on excluding other causes. The shift emphasizes that metabolic dysfunction is a direct contributor to this type of liver disease.
A key risk factor is a high body mass index (BMI) or central obesity. Specifically, a waist circumference greater than 35 inches for women or 40 inches for men is a significant indicator, as this type of adiposity is closely linked to the accumulation of fat within the liver.
Elevated blood sugar levels are another major risk factor. This includes individuals with a formal diagnosis of Type 2 diabetes, as well as those with pre-diabetes, indicated by fasting blood glucose levels of 100 mg/dL or higher. Insulin resistance disrupts normal glucose and fat metabolism, leading to fat deposition in liver cells.
High blood pressure, or hypertension, defined as readings of 130/85 mmHg or higher or the use of medication to control blood pressure, also qualifies as a risk factor. The circulatory stress caused by hypertension can contribute to the systemic inflammation that affects the liver.
Finally, abnormal blood lipid levels are the remaining criteria. This includes having high triglycerides at a level of 150 mg/dL or greater. It also includes having low levels of high-density lipoprotein (HDL) cholesterol, below 40 mg/dL in men and 50 mg/dL in women.
Progression and Associated Health Risks
The journey of metabolic liver disease unfolds along a spectrum, beginning with the simple accumulation of fat. This initial stage, now part of the MASLD definition, can remain stable for years. However, in a subset of individuals, the condition can advance into a more serious form involving liver inflammation, a significant turning point in the disease’s course.
When inflammation accompanies the fatty liver, the condition is called Metabolic Dysfunction-Associated Steatohepatitis, or MASH. MASH is a more aggressive form of the disease where liver cells are not just storing fat but are also becoming injured and inflamed. This inflammatory response is the body’s reaction to the cellular stress caused by excess fat.
Persistent inflammation from MASH can trigger the development of fibrosis, which is the formation of scar tissue in the liver. As the liver repeatedly tries to repair itself, it lays down tough, fibrous tissue. Over time, this scarring can become extensive and stiffen the liver, impairing its function and potentially culminating in cirrhosis, a late stage of scarring that can lead to liver failure.
Beyond the liver itself, METALD poses risks to other parts of the body. The systemic metabolic dysfunction that drives the liver disease also affects the cardiovascular system. Individuals with this condition have a markedly higher risk of experiencing heart attacks and strokes, and the chronic inflammation is linked to an increased risk of certain cancers.
Diagnosis and Monitoring
The initial step in diagnosing metabolic liver disease often involves routine blood tests that measure the levels of specific liver enzymes, such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Elevated levels of these enzymes can signal liver inflammation or cell damage, though these enzyme levels can be normal even when significant fat has accumulated in the liver.
To directly visualize the liver, healthcare providers use imaging studies, with abdominal ultrasound being the most common and accessible method. An ultrasound can reliably detect the presence of steatosis, or fatty deposits, but it does not provide detailed information about inflammation or scarring.
For a more comprehensive, non-invasive assessment, a procedure called transient elastography, known by the brand name FibroScan, is used. This technology uses ultrasound waves to measure both the amount of fat in the liver and the degree of liver stiffness. Liver stiffness is a direct indicator of fibrosis, allowing doctors to stage the disease and monitor its progression without needing to take a tissue sample.
In certain cases, when a precise assessment of inflammation and fibrosis is needed, a liver biopsy may be performed. This procedure involves using a thin needle to extract a small sample of liver tissue for examination. A biopsy is the most accurate method for confirming a diagnosis of MASH and determining the stage of fibrosis, but it is reserved for situations where the results will significantly influence treatment decisions.
Management Through Lifestyle Modifications
The most effective approach to managing METALD is centered on comprehensive lifestyle changes, with weight loss being a primary goal. A weight loss of 7% to 10% can reduce the inflammation and liver cell injury associated with MASH and potentially reverse some degree of fibrosis. This reduction in weight helps improve the body’s sensitivity to insulin and reduces the metabolic stress on the liver.
Dietary adjustments are a fundamental component of managing this condition. The Mediterranean diet is frequently recommended due to its emphasis on whole, unprocessed foods. This eating pattern is rich in fruits, vegetables, whole grains, and nuts, and it uses olive oil as the principal source of fat while limiting red meat and processed foods high in added sugars.
Reducing the consumption of sugary beverages, such as sodas and sweetened juices, is particularly important. These drinks are often high in fructose, a type of sugar that is metabolized in the liver and is a known driver of fat accumulation. Reading food labels to identify and avoid products containing high-fructose corn syrup can significantly decrease the liver’s metabolic burden.
Regular physical activity is another pillar of treatment. A combination of both aerobic exercise, like brisk walking for at least 150 minutes per week, and resistance training, such as lifting weights two or more days per week, is advised. This regimen helps improve insulin sensitivity and builds muscle mass, which improves the body’s ability to manage blood sugar.
Medical Interventions and Future Outlook
Currently, there are no medications specifically approved by the Food and Drug Administration (FDA) for the direct treatment of METALD or its inflammatory form, MASH. The focus of medical management is therefore on controlling the associated metabolic conditions that drive the liver disease. This involves prescribing medications to manage Type 2 diabetes, lower high blood pressure, and control abnormal cholesterol levels.
The management of these coexisting conditions is a standard part of the care plan. For instance, certain diabetes medications have been observed to also reduce liver fat and inflammation as a secondary benefit. Similarly, statins used to lower cholesterol are considered safe and can be beneficial for reducing cardiovascular risk in this population.
The future for treating this condition is promising, as the scientific community is actively working on developing targeted therapies. Several new drugs are currently in the final stages of clinical trials and have shown potential for reducing liver fat, inflammation, and fibrosis. While these potential treatments offer hope, it may still be some time before they are widely available to patients.
For now, the most impactful and proven strategy remains dedicated lifestyle modification. The combination of weight loss, a balanced diet, and consistent exercise is the primary and most effective intervention available. These changes directly address the root causes of the disease and can significantly improve liver health.