INS and obesity due to melanocortin 4 receptor deficiency: Therefore, mice were fed cHF diet between 3 and 7 months of age to induce obesity and to impair glucose homeostasis (see [21]), and then fed either cHF diet, or subjected to cHF+F, or cHF+PIO, or cHF+F+PIO treatment for 2 weeks, until performing an insulin tolerance test (Figs. 1 and 5).