Leptin, the product of the ob (obese) gene, is a 16kD protein consisting of 147 amino acid residues. Leptin is produced in the adipose tissue, and is considered to play an important role in appetite control, fat metabolism and regulation of body weight. It targets the central nervous system, particularly hypothalamus, affecting food intake. Leptin levels are high in most obese individuals. Studies have shown that it may also influence the reproductive function.