Definition of nonalcoholic fatty liver disease (NAFLD)

Nonalcoholic fatty liver disease (NAFLD) is defined as more than 5% liver steatosis (fat) in the absence of another cause such as excess alcohol consumption. It can be divided into:

• nonalcoholic fatty liver (NAFL)—simple fat deposition without liver cell injury or fibrosis
• nonalcoholic steatohepatitis (NASH)—a histologic diagnosis characterised by fat deposition with liver cell injury and inflammation, with or without fibrosis.

Metabolic dysfunction–associated fatty liver disease (MAFLD) has been suggested as a more appropriate term than nonalcoholic fatty liver disease, as it more accurately reflects the pathogenesis of this condition. In addition, while NAFLD is a diagnosis of exclusion, MAFLD has been defined in terms of clear diagnostic criteria. The proposed diagnostic criteria for MAFLD are evidence of fat accumulation in the liver (liver steatosis), plus at least one of the following: overweight/obesity, type 2 diabetes mellitus, or evidence of metabolic dysregulation in a person of low or normal weight (at least two risk factors such as increased waist circumference, elevated blood pressure, dyslipidaemia, prediabetes)¹.