TNF and obesity due to melanocortin 4 receptor deficiency: Obesity, the most common cause of insulin resistance, is increasingly recognized as a low-grade inflammatory state in which overproduction of certain molecules, such as free fatty acids, interleukin-6 (IL-6), adiponectin, leptin, tumour necrosis factor alpha (TNF-α), plasminogen activator inhibitor-1, and monocyte chemoattractant protein (MCP-1), can play a role in malignant transformation and/or cancer progression [14].