What is NAFLD?
NAFLD is defined as fat accumulation in the liver in people who drink little or no alcohol, with no other explanation for the fat build-up. It exists on a spectrum from simple steatosis (fat accumulation without inflammation — relatively benign) to NASH (non-alcoholic steatohepatitis — fat plus inflammation and cell damage) to fibrosis and cirrhosis.
The condition was recently renamed Metabolic dysfunction-Associated Steatotic Liver Disease (MASLD) to better reflect its metabolic origins. You may see either term used in clinical and research contexts.
Causes and risk factors
The metabolic connection
NAFLD is fundamentally a metabolic disease. The strongest risk factors are: obesity (particularly central/visceral fat), type 2 diabetes, insulin resistance, high triglycerides, and metabolic syndrome. It is present in approximately 70–80% of people with type 2 diabetes.
Diet
High intake of fructose (particularly from sugar-sweetened drinks) and saturated fat directly promotes hepatic fat accumulation. The liver uniquely processes fructose and readily converts excess amounts to fat — explaining why sugary drinks are particularly closely linked to NAFLD.
Gut microbiome
Emerging evidence links gut microbiome dysbiosis (reduced diversity and altered composition) to NAFLD development and progression — a connection that is driving research into microbiome-targeted treatments.
Treatment and reversal
NAFLD in its early stages is highly responsive to lifestyle intervention. Weight loss of just 7–10% of body weight has been shown in multiple trials to significantly reduce liver fat, inflammation and fibrosis scores. The intervention producing this weight loss matters less than achieving it — whether through caloric restriction, Mediterranean diet, low-carbohydrate diet or exercise.
Exercise has independent benefits beyond weight loss — aerobic exercise directly reduces liver fat accumulation and improves insulin sensitivity, with evidence of effect even without significant weight loss.
A 7–10% reduction in body weight, achieved through any sustainable method, produces clinically significant improvements in liver histology (as measured by biopsy) in the majority of NAFLD patients. This is one of the most responsive conditions to lifestyle intervention.
Frequently asked questions
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