INS and obesity due to melanocortin 4 receptor deficiency: In addition to obesity (Fig. 2), 4 weeks of HF diet caused insulin resistance, as shown by increased intolerance to exogenous insulin relative to mice fed RD (Fig. 1,i black circles versus white squares, and Fig. 1,ii in the accompanying bar graph depicting the Area Under the Curve (AUC): 14287 ± 458 in HF-water (black bar) versus 11182 ± 691.9 arbitrary units (au) in RD-water (white bar); P <0.05).