Fatty Liver Disease: What It Is, What Causes It, and Why It Matters

Simple fatty liver means fat is present without inflammation - it is generally benign and reversible. NASH (now also called MASH) adds active inflammation and liver cell injury, which can progress to fibrosis and cirrhosis over years. Only NASH carries meaningful long-term liver risk, which is why distinguishing the two matters.

Yes, especially in the early stages. Sustained weight loss of 7-10% of body weight has been shown to clear liver fat and reduce inflammation in many patients. Even mild fibrosis can regress when the underlying drivers - obesity, diabetes, alcohol, certain medications - are corrected. Advanced cirrhosis, however, is generally not reversible.

Simple fatty liver alone carries minimal cancer risk. Once advanced fibrosis or cirrhosis has developed, the risk of hepatocellular carcinoma (HCC) becomes meaningful and patients should enter a surveillance program with imaging every 6 months. NASH-related cirrhosis is now one of the leading causes of HCC in the US.

The Mediterranean dietary pattern has the strongest evidence base: vegetables, legumes, whole grains, nuts, olive oil, fish, and limited red meat. Cutting added sugars and sugar-sweetened drinks (especially fructose) is particularly impactful, since liver fat responds more to sugar than to dietary fat for most patients. Working with a clinician to set a personalised plan tends to outperform generic restriction lists.

Fatty liver is often suspected from elevated liver enzymes on routine bloodwork and confirmed on abdominal ultrasound. To distinguish simple fatty liver from NASH and stage any fibrosis, hepatologists use FibroScan (transient elastography), MR elastography, blood-based fibrosis scores (FIB-4, NFS), and occasionally liver biopsy.

Yes - this is the most common form and is now called MASLD (formerly NAFLD). It is driven by metabolic factors: obesity, type 2 diabetes, insulin resistance, high triglycerides, and metabolic syndrome. Roughly 1 in 4 adults globally has MASLD, the majority of whom drink little or no alcohol.

Exercise meaningfully reduces liver fat even without significant weight loss. Around 150 minutes per week of moderate aerobic activity, plus resistance training twice a week, is the broadly recommended target. It works best when paired with dietary changes and management of diabetes or cholesterol if they are also present.

See a hepatologist if liver enzymes remain elevated, FibroScan suggests fibrosis, you have diabetes plus fatty liver, you have a family history of cirrhosis or liver cancer, or you have any signs of advanced disease (jaundice, abdominal swelling, easy bruising). Earlier evaluation is also reasonable if multiple risk factors are present.

Resmetirom (Rezdiffra) is the first FDA-approved medication for NASH/MASH with significant fibrosis. Other agents - including GLP-1 receptor agonists used for diabetes and weight loss - have also shown benefits on liver fat and inflammation. Lifestyle change remains the foundation of treatment for every patient regardless of which medication is used.

Most patients with simple fatty liver do well long-term. However, those with NASH and progressive fibrosis can develop cirrhosis, liver failure, and an increased risk of liver cancer over years to decades. Even before liver complications, fatty liver is linked to higher cardiovascular and overall mortality, which is why active management matters.