Leptin

Leptin is a hormone produced by fat cells that regulates appetite and energy expenditure. This test measures blood leptin levels, which generally correlate with body fat mass. Leptin tells your brain when you are full and helps regulate metabolism. Abnormally low leptin can indicate insufficient fat stores or hypothalamic dysfunction, while elevated leptin (often with obesity) may indicate leptin resistance, where the body doesn't respond properly to the hormone. Leptin levels help assess metabolic and appetite regulation.