As an increasing number of m6A-related enzymes are recognized, such as methyltransferase-like 3 (METTL3), fat mass and obesity-associated gene (FTO), AlkB homolog 5 RNA demethylase (ALKBH5), and YTH domain family 1 (YTHDF1), the powerful biological functions of m6A modification have been gradually revealed. Here, METTL3 is linked to obesity due to melanocortin 4 receptor deficiency.