Conversely, musclin has been identified as a negative regulator of adipocyte thermogenesis (Jin et al., 2023), and high basal Ostn/musclin expression has been reported in animals and people with obesity, insulin resistance, and type‐2 diabetes (Chen, Liu, Sui, Yang, et al., 2017; Chen, Liu, Sui, Zhang, et al., 2017; Jin et al., 2023; Shimomura et al., 2021). Here, OSTN is linked to obesity due to melanocortin 4 receptor deficiency.