IL6 and obesity due to melanocortin 4 receptor deficiency: Chronic low-grade inflammation, particularly IL-6, has been implicated.<h4>Objective</h4>To assess the role of IL-6 in protein and amino acid metabolism during fasting and postprandial states in humans with healthy weight or obesity at whole-body, skeletal muscle, and subcutaneous adipose tissue levels.<h4>Methods</h4>In this placebo-controlled, nonrandomized, participant-blinded study, 12 men with healthy weight and 12 men with obesity received placebo (0.9% saline) or 3 weeks of IL-6 receptor blockade with tocilizumab.