A growing number of studies found that obesity is characterized by chronic and low-grade inflammation accompanied by an increase in the number of adipose tissue macrophages (ATMs), which play crucial roles in the altered production of several proinflammatory cytokines, such as IL-6 and IL-1β, in the adipose tissues of obese individuals 23-26. Here, IL6 is linked to obesity due to melanocortin 4 receptor deficiency.