CRP and obesity due to melanocortin 4 receptor deficiency: Our study aims to: (1) assess the moderating effect of obesity on the associations of depressive symptoms with inflammation (i.e. CRP), oxidative stress (i.e. γ-glutamyltransferase), and sleep quality; and, (2) determine which of these factors increase the odds of having depressive symptoms in a nationally representative sample of U.S. adults.