Our microarray data also showed a significant elevation of major urinary proteins (MUPs), a lipocalin family that is known to improve glucose tolerance in skeletal muscle (Hui et al., 2009) and significantly lower expression of osteocrin (OSTN), also known as musclin, a myosecretory protein that is expressed in bone and muscle and is shown to be highly upregulated in obesity‐induced insulin resistance (Nishizawa et al., 2004; Shimomura et al., 2021; Watanabe‐Takano et al., 2021; Yu et al., 2016; Zhang et al., 2021) in the 2‐month‐old KO vs. WT mice (Figure 8, Table S1). This evidence concerns the gene OSTN and obesity due to melanocortin 4 receptor deficiency.