People with normal body mass index measurements can still develop fatty liver disease, and individuals living with HIV face unique risks that traditional screening methods often miss, according to study findings presented by researchers at the 26th International AIDS Conference (AIDS 2026) in Rio de Janeiro.
Normal Body Mass Index Fails to Rule Out Liver Disease in HIV Care
Relying strictly on body mass index calculations to evaluate liver health leaves vulnerable patients undiagnosed, according to Florence Bascombe, a senior research nurse at University College London. Bascombe presented findings at AIDS 2026 showing that normal body weight does not exclude clinically relevant liver disease in patients with HIV. Routine reliance on body size alone misses individuals who need metabolic assessment and clinical intervention.
Steatotic liver disease, newly adopted terminology for fat accumulation in the liver, includes metabolic dysfunction-associated steatotic liver disease alongside alcohol-related conditions. While the general population sees about 10% of normal or low-weight individuals develop steatotic liver disease, research suggests that figure climbs to 25% among people living with HIV. Over time, hepatic steatosis leads to inflammation, fibrosis, cirrhosis, and liver cancer if left unmanaged.
Clinical Characteristics of Lean Steatotic Liver Disease
To evaluate the condition among HIV-positive patients, Bascombe and research colleagues analyzed clinical data collected at a large HIV service in central London between 2019 and 2025. Investigators used transient elastography, known as FibroScan, to measure both steatosis and liver stiffness. Out of 391 participants with HIV and fatty liver disease, 57 individuals—representing 14.6% of the cohort—had lean steatotic liver disease, defined as a body mass index under 25.
Compared to participants with overweight or obesity, lean individuals with steatotic liver disease were older, with a median age of 58 years compared to 54 years, and maintained more favorable cardiometabolic profiles. However, both lean and non-lean cohorts displayed similar markers of liver disease severity, including liver fibrosis scores. Hepatitis B co-infection appeared more than twice as frequently among lean participants, affecting 19.3% of the lean group versus 8.1% of those with higher body mass index figures.
Did You Know? Steatotic liver disease is responsible for a growing share of advanced liver disease worldwide, largely due to successful hepatitis C cures and hepatitis B vaccinations.
Pathways Beyond Obesity Driving Liver Fat Accumulation
Lean steatotic liver disease correlates strongly with a history of lipodystrophy, characterized by abnormal body fat distribution such as abdominal fat accumulation alongside fat loss in the face and limbs. Data showed that 10.5% of lean participants with liver disease experienced lipodystrophy, compared to just 2.1% of participants with overweight or obesity. Researchers also linked lean disease presentation to the use of tenofovir alafenamide, an antiretroviral component found in combination pills like Descovy and Biktarvy.
These distinct clinical patterns indicate that lean liver fat accumulation does not merely represent obesity-driven disease occurring at a lower body size. Instead, it likely stems from alternative pathways involving adipose dysfunction, altered fat distribution, or mitochondrial mechanisms unique to people with HIV. Consequently, medical providers are shifting away from body mass index alone and incorporating body composition metrics like waist circumference, waist-to-height ratio, body roundness index, and body fat percentage into patient evaluations.
Pro Tip: Healthcare providers treating patients with HIV should review comprehensive body composition measures rather than relying solely on standard weight scales or body mass index thresholds to screen for metabolic complications.
Frequently Asked Questions
What is lean steatotic liver disease?
Lean steatotic liver disease refers to the accumulation of excess fat in the liver of individuals classified as having normal or low body mass index measurements, typically below 25.
Why are people living with HIV at higher risk for lean liver disease?
Research indicates that factors such as altered fat distribution, lipodystrophy history, specific antiretroviral treatments, and higher rates of hepatitis B co-infection contribute to liver fat accumulation independently of body weight.
How is steatotic liver disease diagnosed?
Clinicians utilize non-invasive ultrasound imaging methods like transient elastography, or FibroScan, to estimate both steatosis and liver stiffness.
Can body mass index accurately screen everyone for liver complications?
No, focusing exclusively on body mass index underestimates fatty liver disease prevalence in lean populations, prompting a shift toward measuring waist circumference, body fat percentage, and body roundness index.
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