Limited human in vivo data have identified subtle disturbances in the growth hormone-IGF-1 axis in women with PCOS, however studies to date have not elucidated if these changes are linked to hyperinsulinemia, obesity or androgen excess (Wu et al., 2000; de Boer et al., 2004). Here, IGF1 is linked to obesity due to melanocortin 4 receptor deficiency.