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FLI scores range from 0 to 100. A score below 30 rules out fatty liver. A score of 60 or above means fatty liver is likely.
The formula was developed in 2006 and has 84% accuracy for detecting hepatic steatosis in the general population.
What you'll learn:
- How FLI is calculated
- What each input measures
- How to interpret your score
- What to do next
The formula combines these into a probability score. The math is complex, but the inputs are straightforward.
Choose Health's Liver Test measures GGT. A comprehensive metabolic panel adds triglycerides.
An FLI below 30 has a negative likelihood ratio of 0.2. Fatty liver is unlikely.
An FLI of 60 or above has a positive likelihood ratio of 4.3. Fatty liver is probable.
Why These Four Inputs Matter
Each component reflects a different aspect of metabolic and liver health.
Triglycerides - Elevated levels indicate the liver is processing more fat than it can export. High triglycerides often accompany insulin resistance.
GGT - This enzyme rises with fat accumulation and oxidative stress. It's often the first marker to elevate in early fatty liver. Learn more about what GGT reveals.
BMI - Higher body mass increases fatty liver risk. But BMI alone doesn't show where fat is stored.
Waist Circumference - Visceral fat around the midsection has a stronger link to fatty liver than overall weight. The original study found waist was one of the strongest predictors.
FLI vs. Other Fatty Liver Assessments
FLI is a screening tool, not a diagnostic test.
FLI works best as a first-line screen. If your score is 60 or above, the next step is typically an ultrasound.
For more context, see our guide on liver function testing.
What to Do Based on Your Score
FLI below 30:Fatty liver is unlikely. Continue healthy habits. Retest annually.
FLI 30-59:Results are inconclusive.
- Recheck in 3-6 months after lifestyle changes
- Consider a liver ultrasound for clarity
- Test ALT, AST, and other liver enzymes for context
FLI 60 or above: Fatty liver is likely.
- Request a liver ultrasound to confirm
- Review metabolic markers (HbA1c, fasting insulin)
- Discuss interventions with your doctor
- Retest in 3-6 months to track progress
Fatty liver is often reversible. A 5-10% reduction in body weight can significantly reduce liver fat. Understanding fatty liver and life expectancy helps put the risk in perspective.
When to Retest
FLI is useful for monitoring, not just initial screening.
Retest after:
- 3-6 months of lifestyle changes
- 5%+ body weight loss
- Starting or stopping medications that affect liver
- Any intervention targeting metabolic health
Track triglycerides and GGT regularly. These blood markers respond to dietary changes. At-home liver testing makes monitoring easier.
FAQ
Is the Fatty Liver Index accurate?
84% accuracy in the original study. Best for ruling out fatty liver (FLI <30) rather than confirming it.
Can I calculate FLI without blood tests?
No. You need triglycerides and GGT from a blood test. BMI and waist can be measured at home.
What's the difference between FLI and HSI?
FLI uses triglycerides, GGT, BMI, and waist. HSI uses ALT, AST, BMI, sex, and diabetes status. Both screen for fatty liver.
Does a high FLI mean liver damage?
Not necessarily. FLI detects fat accumulation, not inflammation or scarring. Additional testing determines progression.
Know Your Liver Numbers
The Fatty Liver Index gives you a non-invasive way to estimate fatty liver risk. If you don't know your triglycerides and GGT levels, testing is the first step.
Explore our liver health survey in under 5 minutes to get your liver's health score
