TNF and Insulin resistance: M2 macrophages predominate in a lean state and help to sustain insulin sensitivity via the secretion of anti-inflammatory cytokines such as IL-4 and IL-10 while M1 macrophages lead to insulin resistance through the secretion of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), IL-6 and IL-1β which, in turn, leads to a pro-inflammatory environment in white adipose tissue (WAT) and the liver [10,12].