In our PWS subjects, the persistent inhibition of PYY secretion during the entire hedonic session likely reflects the orexigenic state occurring in the cephalic phase (or, alternatively, the anticipatory phase) before consumption of highly palatable food, when all (both lean and obese) individuals think about, see and/or smell the food but do not eat it yet [33]. Here, PYY is linked to Prader-Willi syndrome.