RBP4 and obesity due to melanocortin 4 receptor deficiency: An observational trial confirmed that people with obesity have higher levels of leptin, adipsin, retinol binding protein-4 (RBP-4), IL-6, high sensitivity-C reactive protein (Hs-CRP) and lower levels of adiponectin and visfatin as compared to lean people (Derosa et al., 2013).