Vnitr Lek 2026, 72(4):232-239 | DOI: 10.36290/vnl.2026.047

MASLD and its lean phenotype

Kateřina Janstová, Denisa Kyselová, Pavel Trunečka

Klinika hepatogastroenterologie, Institut klinické a experimentální medicíny, Praha

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver disease, with a global prevalence of 30-40%. Although it is typically associated with obesity and metabolic syndrome, a significant and often overlooked group of patients consists of individuals with normal body weight, referred to as the lean phenotype of MASLD. These individuals account for approximately 5-20% of MASLD patients, and their disease is often diagnosed only at advanced stages. The pathogenesis is complex and involves combination of genetic predisposition, visceral adiposity, insulin resistance, and sarcopenia. Despite having a normal body mass index (BMI), these patients have a higher risk of advanced liver disease and increased overall mortality. Diagnosis is often complicated by the absence of typical metabolic risk factors and by limitations of the current definition of MASLD. The article highlights the need to reconsider current diagnostic approaches, place greater emphasis on fat distribution and metabolic health rather than BMI alone and develop appropriate screening strategies for this frequently overlooked patient population.

Keywords: hepatic steatosis, MASLD, MASH, NAFLD, steatohepatitis, lean phenotype, metabolic syndrome, cardiovascular diseases, hepatocellular carcinoma.

Accepted: June 11, 2026; Published: June 24, 2026  Show citation