The acute anorexigenic effect of 24 IU of IN oxytocin in the fasting state has been demonstrated in 25 men across the weight spectrum who were tested 60 min after drug administration [221], in 18 men with obesity evaluated 45 min after administration [222], and in 15 lean men assessed 75 min following oxytocin application [220]. Here, OXT is linked to obesity due to melanocortin 4 receptor deficiency.