Metabolic dysfunction-associated steatotic liver disease (MASLD) is increasingly observed in lean individuals, particularly in non-Western populations. In this prospective Moroccan study, 100 patients with biopsy-proven MASLD were divided into two groups: lean (n=50) and non-lean (n=50). Lean patients were older and displayed a lower prevalence of classical cardiometabolic risk factors such as obesity, diabetes, and metabolic syndrome. However, they more frequently presented with autoimmune comorbidities, suggesting a distinct immuno-inflammatory background. In contrast, advanced fibrosis was significantly more prevalent in non-lean patients. These findings support the notion that lean MASLD constitutes a separate clinical entity with unique risk profiles, highlighting the need for individualized diagnostic and therapeutic approaches.