For example, thiazolidinediones (TZDs), a class of PPARγ agonist compounds, had been used as a therapeutic compound for metabolic disorders such as type 2 diabetes and obesity [8], and it was also reported that the agonists to PPARγ protein had a potential to be used as a new therapeutic approach to cancers, immune disorders, and so on. This evidence concerns the gene PPARG and obesity due to melanocortin 4 receptor deficiency.