Lean Liver Disease: A Hidden Threat Affecting Millions of Americans

New research is shining a light on a concerning trend: lean metabolic dysfunction-associated steatotic liver disease (MASLD) is affecting a larger number of Americans than previously thought. This condition, often associated with overweight and obesity, is being diagnosed in individuals with a healthy weight, highlighting the need for increased awareness and innovative screening methods.

What is Lean MASLD?

MASLD is a type of non-alcoholic fatty liver disease (NAFLD) characterized by fat buildup in the liver. While traditionally linked to obesity and diabetes, lean MASLD affects individuals with a Body Mass Index (BMI) of less than 25 (or less than 23 for Asian populations), who may not exhibit the typical risk factors.

Prevalence of Lean MASLD

A recent study presented at the American College of Gastroenterology (ACG) 2024 Annual Scientific Meeting revealed that an estimated 3.8 million lean US adults were living with MASLD as of 2020. Alarmingly, around 87% of these individuals were unaware of their condition.

"People who are lean, so people with a BMI of less than 25 overall or less than 23 in the Asian population, are often not diagnosed with MASLD because they don’t typically have the risk factors that we expect," explained lead investigator Basile Njei, MD, MPH, PhD, an assistant professor at Yale School of Medicine.

Determining Lean MASLD

The study utilized data from the 2017-2020 National Health and Nutrition Examination Survey (NHANES) to estimate the prevalence of lean MASLD. Researchers defined MASLD based on specific criteria including controlled attenuation parameter, liver stiffness, and portal hypertension. They also analyzed self-reported diagnoses from the NHANES Medical Conditions Questionnaire.

Call for Improved Screening

The findings underscore the urgent need for improved screening methods for lean MASLD. Dr. Njei suggests focusing on other markers of cardiometabolic risk, such as insulin resistance, which can be present even before diabetes develops.

He also envisions future research incorporating artificial intelligence and genetics into screening practices to better identify individuals at risk.

Don’t ignore the signs. Talk to your doctor about your liver health, especially if you experience any unusual symptoms. Early detection and intervention are crucial for managing MASLD and preventing potentially serious complications.