adiponectin

Adiponectin is one of fat tissue's “good news” hormones. Counterintuitively, the leaner and healthier the fat tissue, the more of it is released — and high levels are associated with tissues that respond well to insulin and with lower inflammation. It is almost the opposite of the harmful signals that come from overstuffed, dysfunctional fat.

Adiponectin is a protein hormone secreted by adipocytes (fat cells). It acts on liver and muscle to enhance insulin sensitivity, promote the burning of fatty acids, and reduce glucose production by the liver, partly by activating an energy-sensing enzyme (AMP-activated protein kinase). It also has anti-inflammatory and vessel-protective actions. Unusually for a fat hormone, its blood levels fall as fat mass rises in obesity.

Low adiponectin is linked to insulin resistance, type 2 diabetes, and cardiovascular disease, which made it a hopeful therapeutic target. In practice, delivering adiponectin as a drug has been difficult because of its complex structure, so it remains more useful as a biomarker than as a treatment so far.