SIRT1 and obesity due to melanocortin 4 receptor deficiency: SIRT1, for example, is involved in regulating the expression of adipokines such as adiponectin and TNF-α, has been linked to hypothalamic control of energy balance, plays a role in adipogenesis, and is involved in the regulation of lipolysis and fatty acid mobilization in response to fasting.[29] Evidence from animal studies in which sirtuins are under- or over-expressed, and from limited human evidence, also suggest a role for sirtuins in obesity.