TNF and obesity due to melanocortin 4 receptor deficiency: Despite the regulative role of exercise training on the circulating concentration levels of CRP, IL-6, IL-10 and TNFα observed here, the amount of evidence and the disparity among participants’ characteristics, training protocols, and methods used to determine cytokines concentration levels in blood were major limitations of this systematic review, all of which complicate the understanding of exercise training effects on low-grade systemic inflammation in adults with overweight and obesity.