Abstract: Recently the hormone leptin has been regarded as hormonal signal linking adipose tissue status with a number of key central nervous system circuits. The role of leptin and its feedback system in man is partly revealed. Hypothalamic centers appear to control appetite, metabolic rate and activity level in a coordinate manner. Within the hypothalamus, known weight regulatory molecules include leptin, neuropeptide Y and POMC. We integrated new information into a revised model for understanding this important regulatory process. Our model of energy homeostasis propose that the inter-action of leptin with various neuroendocrine pathway in the brain and in the periphery to affect food-take.