LEP and obesity due to melanocortin 4 receptor deficiency: Excessive nutrient intake is key in the genesis of obesity and type 2 diabetes: adipocytes and macrophages in the white adipose tissue respond to molecules such as free fatty acids, advanced glycation end products and reactive oxygen species (Figure 4) with the production of TNF-α, IL-1β, IL-6, CCL2 and adipokines like leptin [80].