Obesity is highly prevalent in industralized countries and is increasing worldwide. It is also a major risk factor for type 2 diabetes, hypertension, coronary artery disease and certain cancers. An understanding of the regulation of eating behavior is pertinent to obesity, as the latter results from an imbalance between food consumption and energy expenditure. Leptin and other hormones regulate feeding and energy balance by modulating the expression of neuropeptides in the brain. Major efforts are underway to determine whether the peripheral and central pathways involved in the regulation of feeding behavior and energy balance could be targeted for the treatment of obesity.