GDF15 and obesity due to melanocortin 4 receptor deficiency: GDF15 affects the energy metabolism of the body by activating the GFRAL receptor, e.g., it enhances fatty acid β-oxidation and reduces appetite thus preventing obesity as well as inducing cachexia and sarcopenia (Hsu et al. 2017; Tsai et al. 2018; Breit et al. 2021).