What is Fatty Liver Disease?
Fatty liver disease is a condition where excess fat builds up in your liver cells—specifically, when more than 5% of your liver's weight becomes fat. 1
Understanding the Basics
Your liver normally contains some fat, but when too much accumulates, it can cause problems. Think of it like your liver becoming "overloaded" with fat that it cannot process efficiently. 1
There are two main types depending on the cause:
Non-Alcoholic Fatty Liver Disease (NAFLD)
- This occurs when fat builds up in your liver without significant alcohol consumption (less than 2 drinks per day for men, less than 1 drink per day for women). 1
- It is strongly linked to being overweight, having diabetes, high cholesterol, or high blood pressure—conditions often grouped together as "metabolic syndrome." 1
- NAFLD is extremely common, affecting 20-30% of the general population, and up to 70% of people with obesity. 2, 3
Alcohol-Related Fatty Liver Disease
- This develops when fat accumulates due to drinking too much alcohol (more than 2-3 drinks daily for men, more than 1-2 drinks daily for women). 1, 4
The Disease Spectrum
Fatty liver disease exists on a spectrum from mild to severe: 1
Simple Fatty Liver (Steatosis):
- Just fat accumulation without inflammation or damage to liver cells. 1
- This is relatively benign and progresses slowly, if at all. 1, 5
- Most people with simple fatty liver remain stable and do not develop serious liver problems. 1
Steatohepatitis (NASH when non-alcoholic):
- Fat accumulation plus inflammation and damage to liver cells (called "ballooning"). 1
- This more aggressive form can progress to scarring (fibrosis) of the liver. 1
- Affects about 3-5% of the general population. 1
Advanced Fibrosis and Cirrhosis:
- When inflammation continues, scar tissue builds up and the liver becomes hardened and unable to function properly. 1
- This can lead to liver failure or liver cancer in some cases. 1, 2
Why It Matters
Most people with fatty liver disease have no symptoms at all—it is usually discovered accidentally through blood tests showing mildly elevated liver enzymes or imaging studies done for other reasons. 2, 3
However, fatty liver disease is important because: 2, 5
- It increases your risk of heart disease and stroke (your biggest health risk). 3, 5
- It increases your risk of developing type 2 diabetes. 5
- In its more severe forms, it can progress to serious liver disease requiring transplantation. 3, 6
Common Pitfall to Understand
Having fatty liver disease does not mean you will definitely develop cirrhosis or liver failure. The vast majority of people with simple fatty liver remain stable throughout their lives. 1 The key is identifying those at higher risk (particularly those with inflammation and scarring) who need closer monitoring and more aggressive treatment. 1, 3