Role of Immune System in Obesity-related Inflammation and Cardiometabolic Risk

Inclusion Criteria: Lean, metabolically healthy group - Body mass index (BMI) 18.5-24.9 kg/m2, HbA1C ≤5.6%, fasting plasma glucose concentration \<100 mg/dl, 2-h OGTT plasma glucose concentration \<140 mg/dl and intrahepatic triglyceride (IHTG) content ≤5%. Obese, metabolically healthy group - BMI ≥30 kg/m2, HHbA1C ≤5.6%, fasting plasma glucose concentration \<100 mg/dl, 2-h OGTT plasma glucose concentration \<140 mg/dl and intrahepatic triglyceride (IHTG) content ≤5%. Obese, metabolically healthy group - BMI ≥30 kg/m2, IHTG content ≥5.6% and HbA1C ≥5.7% or fasting plasma glucose concentration ≥100 mg/dl or 2-h OGTT plasma glucose concentration ≥140 mg/dl. Lean, scheduled for inguinal hernia, hysterectomy or myomectomy surgery - BMI 18.5-24.9 kg/m2, HbA1C ≤5.6%, fasting plasma glucose concentration \<100 mg/dl, 2-h OGTT plasma glucose concentration \<140 mg/dl and IHTG content ≤5%. Obese, scheduled for bariatric and gallbladder surgery - BMI ≥35.0kg/m2 Exclusion Criteria: * active or previous history of liver diseases other than NAFLD * history of alcohol abuse * currently consuming ≥20 g alcohol/day * severe hypertriglyceridemia (\>300 mg/dL) * smoke tobacco * cancer diagnosis within the previous 5 years * medications that might confound the study results * pregnancy or lactation * exercise \>2 h/week