More than a decade ago, the early protein hypothesis was established suggesting that a high protein intake in excess of infant requirements can promote early weight gain (i.e., a rapid increase in infant weight), an increased later obesity risk, along with elevating insulinogenic amino acids, insulin release and insulin-like growth factor 1 (IGF-1) in infant blood and tissues [10]. Here, IGF1 is linked to obesity due to melanocortin 4 receptor deficiency.