IGF1 and obesity due to melanocortin 4 receptor deficiency: The inhibition of the signaling pathway in the gh–ghr–igf axis led to decreased serum Gh levels that may affect insulin secretion, and caused over up-regulation of lipid metabolism in the fat cells resulting in obesity or promoting gluconeogenesis resulting in elevated blood glucose levels (Hwu et al., 1997; Lu et al., 2013).