There is conflicting evidence as to whether GPR55 agonists or antagonists might be of benefit in the treatment of obesity or type 2 diabetes (Lipina et al., 2012; Moreno-Navarrete et al., 2012; Henstridge, Brown & Waldhoer, 2016). This evidence concerns the gene GPR55 and obesity due to melanocortin 4 receptor deficiency.