LEP and obesity due to melanocortin 4 receptor deficiency: The hypothalamic inflammation associated with high-fat diet is a very rapid process—the astrogliosis and increased level of proinflammatory cytokines become observable as soon as 48 hours after starting the diet; therefore, it is proposed that the hypothalamic inflammation is an initiating factor in metabolic dysregulation, i.a. insulin and leptin resistance, impaired thermogenesis, associated with obesity[72,77].