TLQP-21 is one of many bioactive products derived from post-translational cleavage of the C-terminal region of VGF, a propeptide that could be involved in psychiatric, neurologic and metabolic disorders (Carrette et al., 2003; Ruetschi et al., 2005; Bartolomucci et al., 2011; Busse et al., 2012). Here, VGF is linked to metabolic disease.