INS and obesity due to melanocortin 4 receptor deficiency: Notably, the protective effect of eosinophils against high-fat diet-induced obesity in mice was first reported in 2011 by Wu et al.9 Their study demonstrated that C57BL/6 mice lacking eosinophils (ΔdblGATA mice) and fed a high-fat diet exhibited increased body fat, impaired glucose tolerance, and decreased insulin sensitivity compared to their wild-type littermate control mice.