This single-center, prospective observational study aims to assess the accuracy of FIB-4 cut-offs in identifying liver fibrosis in obese patients attending an endocrinology outpatient clinic in Italy.

All consecutive eligible patients undergo routine blood tests and liver elastography (FibroScan) as part of clinical practice; FIB-4 values will be calculated and compared with liver stiffness measurements to evaluate the performance of FIB-4 thresholds for directing patients to FibroScan and hepatology care.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a frequent complication of metabolic syndrome and obesity and may progress to advanced fibrosis, cirrhosis and hepatocellular carcinoma.

Recent EASL-EASD-EASO guidelines recommend the use of the FIB-4 score as a first-line non-invasive tool to stratify the risk of advanced fibrosis in patients with metabolic risk factors, including those with obesity.

However, current FIB-4 cut-offs may lead to a high number of positive cases and an important burden of further liver stiffness assessment.

This study will prospectively enroll obese patients referred to the Clinical Nutrition Center for the Research and Care of Obesity and Metabolic Diseases at IRCCS "Saverio de Bellis".

During a Day Service access, patients undergo routine blood tests and FibroScan; FIB-4 is calculated using age, AST, ALT and platelet count.

Patients will be classified according to FIB-4 (≥1.3 vs <1.3), and FIB-4 performance in predicting liver fibrosis, as assessed by liver stiffness, will be evaluated using correlation analyses, Bland-Altman plots, agreement measures and ROC curves.

Inclusion Criteria:

• Obesity class I or II (body mass index, BMI ≥ 30 kg/m² and ≤ 40 kg/m²)
• Age > 18 years and < 65 years.
• Ability to provide written informed consent after adequate information on the study objectives.
• Arm 1: patients with FIB-4 ≥ 1.3.
• Arm 2: patients with FIB-4 < 1.3.

Exclusion Criteria:

• Lack of signed informed consent.
• Pregnancy or breastfeeding.
• Known liver diseases that rule out MASLD (MetALD, alcoholic liver disease, liver cirrhosis, hepatocellular carcinoma, viral hepatitis, autoimmune hepatitis).
• Current treatment with anti-obesity or type 2 diabetes medications with a known effect on hepatic steatosis (Semaglutide or Tirzepatide).

Consecutive adult obese patients (BMI ≥ 30 and ≤ 40 kg/m²), aged 18-64 years, attending the outpatient Clinical Nutrition Center for the Research and Care of Obesity and Metabolic Diseases at IRCCS "Saverio de Bellis" (Castellana Grotte, Italy). Patients are enrolled during a Day Service access in which routine blood tests and liver stiffness measurement by FibroScan are performed as part of standard clinical practice. Patients are stratified into two cohorts based on FIB-4 score: Cohort 1 (FIB-4 ≥ 1.3) and Cohort 2 (FIB-4 < 1.3). Patients with known liver diseases other than MASLD, pregnancy, or current treatment with GLP-1 receptor agonists known to affect hepatic steatosis (Semaglutide or Tirzepatide) are excluded