Using CD8+ T cell deficient mice and CD8 antibody depletion, Nishimura et al. showed reduced adipose tissue inflammation and insulin resistance (6), while another report showed that transfer of CD8+ T cells into T cell deficient RAG1-HFD mice did not worsen the obesity-associated complications (8). The gene discussed is CD8A; the disease is obesity due to melanocortin 4 receptor deficiency.