TOPLINE

New obesity definitions from the European Association for the Study of Obesity (EASO) and The Lancet Commission reclassified a substantial proportion of patients with metabolic dysfunction‑associated steatotic liver disease (MASLD) as having obesity — yet these newly classified patients carried no higher risk for liver-related events than their peers without obesity. In contrast, BMI‑defined obesity remained a strong risk predictor, with markedly higher liver-related event rates than in the BMI-defined normal-weight group.

METHODOLOGY

• Although BMI has long been the standard for classifying obesity, it does not capture body composition or adequately reflect obesity-related organ dysfunction. Newer obesity definitions from the EASO and The Lancet Commission that incorporate waist measures may reclassify many individuals as having obesity, but whether these newly labeled individuals face a greater risk for adverse liver outcomes remains uncertain.
• Researchers analyzed data from 12,583 patients with MASLD (mean age, 52 years; 58.6% men) drawn from the multinational Vibration-Controlled Transient Elastography-Prognosis cohort.
• Three definitions of obesity were applied: BMI alone, the EASO criteria (requiring BMI-defined obesity or overweight with a waist-to-height ratio ≥ 0.5 plus at least one comorbidity), and The Lancet Commission criteria (requiring BMI-defined obesity plus at least one elevated body size measure, or at least two elevated body size measures regardless of BMI, or BMI ≥ 40).
• The primary outcome was liver-related events — a composite of hepatic decompensation, hepatocellular carcinoma, liver transplantation, and liver-related death — assessed over a median follow-up of 47.5 months.
• Secondary outcomes included progression of liver stiffness (defined as an increase from < 10 kPa at baseline to ≥ 15 kPa during follow-up), separate evaluations of liver cancer and hepatic decompensation, and all-cause mortality.

TAKEAWAY

• During the follow-up period, 1.9% (n = 240) of patients developed liver-related events. BMI-defined obesity was associated with nearly double the risk for liver-related events compared with BMI-defined normal weight (adjusted subdistribution hazard ratio [aSHR], 2.04; P = .005); BMI-defined obesity was also linked to greater risk for liver stiffness progression.
• Many patients who were not identified as having obesity by BMI were reclassified as having obesity under the new definitions: EASO labeled 20.4% of patients with BMI-defined overweight as having obesity, while The Lancet criteria reclassified 34.1% of patients without BMI-defined obesity as having obesity.
• Patients newly classified as having obesity did not have a significantly higher risk for liver-related events, whether under the EASO definition (new obesity vs normal weight: aSHR, 1.15; 95% CI, 0.64-2.08) or The Lancet criteria (new obesity vs The Lancet nonobesity: aSHR, 0.75; 95% CI, 0.42-1.34).
• Additional analyses found that the risk for liver-related events rose significantly only when the waist-to-height ratio approached about 0.6.

IN PRACTICE

“Although the new obesity definitions proposed by EASO and Lancet substantially increase the proportion of individuals classified as obese, they currently do not offer improved risk stratification for hepatic outcomes. Incorporating higher thresholds for WC [waist circumference]-based measures may enhance risk stratification within these new obesity frameworks and warrants further evaluation,” the study authors wrote.

SOURCE

The study was led by Jie Cai, Southern Medical University, Guangzhou, and Terry Cheuk-Fung Yip, The Chinese University of Hong Kong, Hong Kong SAR, China. It was published online in Hepatology.

LIMITATIONS

Missing data reduced the number of patients who could be classified under the new obesity frameworks and may have introduced selection bias. Hip circumference was not recorded, so The Lancet definition could not be applied fully. Finally, the number of liver events during follow‑up was relatively small.

DISCLOSURES

The study was supported by the Noncommunicable Chronic Diseases National Science and Technology Major Project of China, the Hong Kong SAR Government, and The Chinese University of Hong Kong. Several authors disclosed financial relationships with a wide range of companies, including Medscape Medical News. These relationships included consulting and advisory fees, speaker honoraria, research funding, employment or stock holdings, royalties, and service on speakers bureaus or adjudication committees.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.