IL6 and obesity due to melanocortin 4 receptor deficiency: Elevated plasma levels of inflammatory cytokines (including interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6 and C-reactive protein) have been reported in obese patients (Park et al., 2005; Capuron et al., 2011a) and different animal models of obesity (Xu et al., 2003; De Souza et al., 2005; Cani et al., 2009; Pistell et al., 2010; Dinel et al., 2011, 2014; Lawrence et al., 2012).