When comparing the participants with obesity to the lean participants without regards to sex, splanchnic palmitate release was greater in the participants with obesity under basal (23 ± 5 μmol/min vs. 9 ± 1 μmol/min, respectively, P = 0.01), low-dose insulin (14 ± 2 μmol/min vs. 7 ± 1 μmol/min, respectively, P = 0.02), and high-dose (8 ± 1 μmol/min vs. 5 ± 1 μmol/min, respectively, P = 0.049) conditions. This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.