INS and obesity due to melanocortin 4 receptor deficiency: When plotted against results obtained in non-PWS controls, reasons for higher insulin sensitivity in PWS include a modest accumulation of visceral fat after adjustment for total adiposity (13), an disproportionately elevated ghrelin concentration for the degree of obesity (8, 14), high levels of adiponectin (10) and an impaired GH secretion (15).