Our experiments demonstrated that ODNR01 had no effect on obesity and insulin resistance in lymphocyte-free Rag1-null DIO mice, while it improved insulin sensitivity in Rag1-null DIO mice that received CD4+ T-cell adoptive transfer suggesting that the benefits of ODNR01 in obese mice and in WAT are CD4+ T-cell-dependent. This evidence concerns the gene RAG1 and obesity due to melanocortin 4 receptor deficiency.