Clinicopathological characteristics and metabolic profiles of non-alcoholic fatty liver disease in Indian patients with normal body mass index: Do they differ from obese or overweight non-alcoholic fatty liver disease?

BACKGROUND: Obesity is an important risk factor for non-alcoholic fatty liver disease (NAFLD); however, NAFLD does occur in lean subjects. This study was aimed to evaluate the magnitude, clinical, pathological, and metabolic profiles of NAFLD in normal body mass index (BMI) subjects (defined as lean NAFLD) in comparison to overweight or obese NAFLD and lean healthy control. MATERIALS AND METHODS: 336 subjects (205 consecutive NAFLD, and 131 healthy controls) were studied. RESULTS: Among 205 NAFLD patients, 27 (13.2%) were lean, while 141 (68.8%) and 37 (18%) patients were obese and overweight, respectively. The lean NAFLD compared to obese NAFLD had significantly lesser degree of fasting hyperinsulinemia (P < 0.001), homeostasis model assessment insulin resistance (HOMA-IR, P < 0.001), and lower prevalence of diabetes mellitus (P = 0.01) and metabolic syndrome (P < 0.001). The profiles of serum lipids were similar between all 3 BMI categories, and 89% of lean NAFLD were dyslipidemic. Compared to obese subjects, patients with lean NAFLD had less hepatic necro-inflammation (P = 0.05) and fibrosis (P < 0.001). However, the proportion of steatohepatitis and advanced fibrosis were similar between all BMI categories. The profiles of overweight NAFLD were similar to those of lean NAFLD, except for higher HOMA-IR, uric acids and male gender in overweight group. Despite being lean, the mean BMI of lean NAFLD were still higher than unselected lean healthy controls (P = 0.02). CONCLUSIONS: Lean NAFLD patients have less severe disease, minor, or no insulin resistance, but are frequently dyslipidemic and have BMI higher than lean healthy control.