With respect to the ability of low-protein plant-based diets to activate the GCN2-eIF2a-ATF4 pathway, this pathway, which enhances expression of FGF21 and adiponectin, may help to rationalize the lower risks for obesity, diabetes, cardiovascular disorders, autoimmunity and some “Western” types of cancer that have characterized some quasi-vegan societies [146,178]. This evidence concerns the gene FGF21 and obesity due to melanocortin 4 receptor deficiency.