Owing to properties of driving white adipose tissue browning (Wu and Spiegelman, 2014), alleviating insulin resistance (Bostrom et al., 2012; Yuksel Ozgor et al., 2020), improving glucose homeostasis, and liver lipid accumulation (Zhang et al., 2013; Kurdiova et al., 2014), irisin is emerging as a key molecular for metabolic diseases and other disorders known to improve with exercise (Seo et al., 2020). Here, FNDC5 is linked to metabolic disease.