Metabolic (dysfunction)-associated fatty liver disease in individuals of normal weight

Nat Rev Gastroenterol Hepatol. 2022 Oct;19(10):638-651. doi: 10.1038/s41575-022-00635-5. Epub 2022 Jun 16.


Metabolic (dysfunction)-associated fatty liver disease (MAFLD) affects up to a third of the global population; its burden has grown in parallel with rising rates of type 2 diabetes mellitus and obesity. MAFLD increases the risk of end-stage liver disease, hepatocellular carcinoma, death and liver transplantation and has extrahepatic consequences, including cardiometabolic disease and cancers. Although typically associated with obesity, there is accumulating evidence that not all people with overweight or obesity develop fatty liver disease. On the other hand, a considerable proportion of patients with MAFLD are of normal weight, indicating the importance of metabolic health in the pathogenesis of the disease regardless of body mass index. The clinical profile, natural history and pathophysiology of patients with so-called lean MAFLD are not well characterized. In this Review, we provide epidemiological data on this group of patients and consider overall metabolic health and metabolic adaptation as a framework to best explain the pathogenesis of MAFLD and its heterogeneity in individuals of normal weight and in those who are above normal weight. This framework provides a conceptual schema for interrogating the MAFLD phenotype in individuals of normal weight that can translate to novel approaches for diagnosis and patient care.

Publication types

  • Review
  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Carcinoma, Hepatocellular* / pathology
  • Diabetes Mellitus, Type 2* / complications
  • Diabetes Mellitus, Type 2* / etiology
  • Humans
  • Liver Neoplasms*
  • Non-alcoholic Fatty Liver Disease* / complications
  • Obesity / complications