The secretion of pro-inflammatory molecules also affects mast cells and neutrophils; these cell populations are increased in conditions of obesity and, by releasing molecules such as TNF-α, IL-1b, IL-6, IL-4 and elastase, seem to promote the inflammatory state, playing a role in the onset of insulin resistance (IR) [59,60,61,62]. Here, IL6 is linked to obesity due to melanocortin 4 receptor deficiency.