Non-Alcoholic Fatty Liver Disease (NAFLD) has become a common health concern, affecting an estimated 32% of the global population. This condition involves the accumulation of excess fat in the liver, known as hepatic steatosis, and is strongly linked to metabolic disorders like obesity and type 2 diabetes. Because traditional diagnostic methods like ultrasound or liver biopsy are costly and invasive, simple, non-invasive screening tools are needed. The Fatty Liver Index (FLI) is a validated, mathematically derived score that utilizes routine clinical measurements to estimate the likelihood of hepatic steatosis.
What the Fatty Liver Index Measures
The Fatty Liver Index is a diagnostic algorithm designed to estimate hepatic steatosis without requiring specialized imaging or tissue sampling. It serves as a practical, first-line screening tool to assess a person’s risk for Non-Alcoholic Fatty Liver Disease (NAFLD). The FLI is calculated using a mathematical formula that combines four readily available clinical and laboratory measurements. This approach allows healthcare providers to identify high-risk individuals who may require further, more definitive diagnostic testing, such as an abdominal ultrasound. A score below 30 helps rule out fatty liver, while a score of 60 or above helps rule it in.
The Four Data Points Used in Calculation
The calculation of the Fatty Liver Index relies on four specific metrics, each reflecting a different aspect of metabolic health linked to liver fat accumulation. These four inputs are Body Mass Index (BMI), Waist Circumference, Triglycerides, and Gamma-Glutamyl Transferase (GGT).
Body Mass Index (BMI) is included as a measure of general body adiposity, calculated from a person’s weight and height. Excess body weight, particularly when classified as overweight or obese, is a major driver of NAFLD, making BMI a necessary component of the index.
Waist Circumference is the second anthropometric measure, and it reflects the amount of visceral fat stored around internal organs, including the liver. High visceral fat is closely associated with insulin resistance and the development of fatty liver.
Triglycerides, a type of fat found in the blood, are a standard component of a lipid panel. High levels often indicate a disorder in fat metabolism and are frequently observed in individuals with fatty liver disease.
Gamma-Glutamyl Transferase (GGT) is an enzyme found primarily in liver cells, measured in a blood test. Elevated levels serve as a marker for liver stress, injury, or inflammation, which directly correlates with the presence of hepatic steatosis.
Understanding Your FLI Risk Score
The resulting Fatty Liver Index score is a numerical value ranging from 0 to 100, used to stratify an individual’s risk for hepatic steatosis. The standard interpretation utilizes three distinct zones to guide follow-up care.
A score below 30 is typically classified as Low Risk, meaning the probability of having fatty liver is minimal, often less than 10%. Scores between 30 and 60 are considered Intermediate Risk, suggesting an inconclusive result where the presence of fatty liver cannot be definitively ruled out or confirmed. For individuals in this range, monitoring and a closer look at other health markers are usually recommended.
A score of 60 or higher indicates a High Risk for hepatic steatosis, correlating with a high probability of the condition being present. Individuals in this high-risk category are advised to undergo further diagnostic testing, such as an abdominal ultrasound.
Improving the Underlying Metrics
Targeting the four components of the FLI—BMI, Waist Circumference, Triglycerides, and GGT—is the most effective way to improve the score and overall liver health. Weight loss is the single most impactful intervention, with a sustained reduction of 5% in body weight shown to improve steatosis, and a 7% to 10% loss capable of improving liver inflammation. Achieving a caloric deficit is a primary strategy for lowering BMI and waist circumference.
Specific dietary changes can significantly impact triglyceride levels, particularly reducing the intake of refined carbohydrates and fructose. Adopting a Mediterranean-style diet, which emphasizes whole grains, lean protein, and healthy fats, helps regulate fat metabolism and contributes to lower blood lipid levels.
Physical activity, including both aerobic exercise and resistance training, helps decrease visceral fat, thereby reducing waist circumference and improving insulin sensitivity. Regular exercise, aiming for at least 150 minutes per week of moderate-intensity activity, reduces intrahepatic fat and improves liver enzyme levels, including GGT. This improvement reflects a decrease in liver stress and inflammation.