GHR and obesity due to melanocortin 4 receptor deficiency: In this study, we established a liver-specific <i>Ghr</i> knockout (LGHRKO) mouse model that faithfully recapitulates non-obese MAFLD, characterized by hepatomegaly, elevated serum lipids and transaminases, and pronounced hepatic lipid accumulation, all occurring in the absence of obesity or increased adiposity.