In conclusion, the current study revealed that papain treatment could inhibit obesity progression by regulating lipid accumulation and lowering blood lipid levels through the downregulation of adipogenic factors including PPARγ, C/EBPα, and SREBP-1 in HFD-induced obese mice and 3T3-L1 preadipocytes. This evidence concerns the gene PPARG and obesity due to melanocortin 4 receptor deficiency.