INS and obesity due to melanocortin 4 receptor deficiency: A comprehensive summary of the included articles was conducted, focusing on the following obesity-related parameters: food intake, body weight gain, epididymal fat size, adipocyte size, liver weight, serum alanine transaminase (ALT) and aspartate transaminase (AST), insulin and tumour necrosis factor-α (TNF-α), and the lipid profile (total cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-c), and low-density lipoprotein cholesterol (LDL-c)).