DAY 3: Lean Individuals Are Not Exempt from Steatotic Liver Disease or Its Complications

A meta-analysis presented at the 2025 Annual Scientific Meeting of the American College of Gastroenterology in Phoenix, Arizona showed that lean individuals may develop metabolic dysfunction-associated steatotic liver disease (MASLD) and associated complications, although they are at a lower risk for these conditions than people with higher BMI, who are classified as overweight. 

MASLD is a condition with significant metabolic drivers, which has been historically associated with obesity, type 2 diabetes, and their complications. Although individuals with a normal BMI (defined as BMI < 25 kg/m², with a lower cutoff of < 23 kg/m² in Asian populations) may also develop MASLD, their clinical profiles and outcomes have not been closely studied. As a consequence, there are no screening or management strategies targeting lean individuals. 

“Are current screening strategies, based on obesity alone, adequate for lean individuals?” asked Mexan Mapouka, MD, a resident at the University of Maryland Capital Region Health, in Largo, Maryland, who presented the results. The question prompted a meta-analysis of 31 studies published in the past 20 years, including 10.7 million participants, which were selected after a careful review of multiple databases. The final analysis included nine studies from North America, one from South America (Argentina), 11 from Asia, seven from Europe, and two studies with global populations. Mapouka and colleagues compared hepatic and cardiovascular outcomes between lean and non-lean individuals by looking at studies that reported at least one outcome, such as metabolic dysfunction-associated steatohepatitis (MASH), formerly known as nonalcoholic steatohepatitis (NASH), liver fibrosis, hepatic steatosis, cirrhosis, hypertension, cardiovascular disease, and mortality. 

The analysis showed that non-lean individuals had higher odds of developing liver fibrosis, steatosis, hypertension, and cirrhosis compared with their lean counterparts. However, lower BMI did not provide absolute protection against cirrhosis. Moreover, when looking at cardiovascular disease and MASH/NASH, there was no statistically significant difference between the two groups. Non-lean individuals had a higher risk of mortality overall, but lean individuals still experienced this outcome in some studies. 

“Non-lean individuals with MASLD are more likely to develop liver fibrosis, steatosis, and cirrhosis, which we already [suspected], because obesity is a risk factor,” Mapouka concluded. “However, lean patients with MASLD are not spared. Obesity should not be the sole criterion for MASLD risk assessment.” 

Models for risk stratification should factor in metabolic markers, body fat percentage, and ethnicity-specific thresholds. Expanding screening and surveillance of MASLD beyond BMI could improve detection of disease and boost prevention efforts.