GAA and obesity due to melanocortin 4 receptor deficiency: Spent brewer yeast or baker’s yeast extracts, rich in oligopeptides, are widely marketed for dietary supplementation purposes, and their biological properties are explored to confirm the claimed bio-functionalities, such as antioxidant, antihypertensive, antimicrobial, alpha-glucosidase inhibitor, anti-lipolysis, anti-diabetes, mitogenic, immunomodulatory, and anti-obesity properties [2,7,25].