GPT and obesity due to melanocortin 4 receptor deficiency: Recently, we developed a clinically relevant mouse steatohepatitis model consisting of 3-month high-fat diet (HFD) feeding plus 1 binge of ethanol (HFD+1B).7, 8, 9 Three-month HFD feeding alone caused obesity and severe fatty liver with a mild increase of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, but little or no hepatic neutrophil infiltration.