Leptin is also called OB protein. It is the expression product of obesity gene in adipocytes. Single-chain protein molecule with molecular weight of 16000 contains 167 amino acid residues, and has strong hydrophilicity, and its N-terminal contains secretory signal peptide.

Leptin production and adipocytes, a hormone-like substance, can be secreted into the blood from adipocytes, and leptin receptors are found in choroid and hypothalamus. Leptin may regulate weight through a feedback system, and it may be made into diet pills and applied to people's daily lives.