NKT cell subgroups demonstrate varying effects in obesity-induced inflammation, where classical invariant NKT cells appear to induce insulin resistance by inflammatory cytokine secretion, particularly in response to obesity-induced lipid excess, but the non-classical NKT subgroup promotes insulin sensitivity through the secretion Th2-type cytokines [48,49]. This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.