In the obesity and MASLD model, the relative abundance of Bacteroidia, Clostridia, Prevotellaceae_UCG-003 and Oscillibacter was negatively correlated with weight gain (p < 0.05), ALT (p < 0.05), AST (p < 0.05) and LDL (p < 0.05) plasma levels were negatively correlated with and positively correlated with HDL levels (p < 0.05). This evidence concerns the gene GPT and obesity due to melanocortin 4 receptor deficiency.