In a study of insulin-resistant (n = 28) and insulin-sensitive (n = 28) women with overweight or moderate obesity, there was a clear between-group difference in FFA levels during stage 1 of the IST caused by an insufficient suppression of lipolysis in the insulin resistant group, and the authors claim the stage 1 FFA to be more informative than stage 1 SSPG [22]. Here, INS is linked to obesity due to melanocortin 4 receptor deficiency.