GDF15 plasma levels are elevated in animal models of obesity (Lockhart et al., 2020; Xiong et al., 2017); however, administration of recombinant protein robustly lowers body weight in obese and diabetic animals, including non-human primates (Mullican et al., 2017; Xiong et al., 2017). This evidence concerns the gene GDF15 and obesity due to melanocortin 4 receptor deficiency.