During obesity, MCP-1 concentrations are increased in inflamed adipose tissue and it has been observed that MCP-1 interacts with hypertrophic adipocytes and adipose tissue resident macrophages to upregulate production of itself and other inflammatory cytokines, such as TNF-α and IL-6; contributing to the low-grade systemic inflammatory condition characteristic of excessive adiposity28,55,56. Here, TNF is linked to obesity due to melanocortin 4 receptor deficiency.