The brain and the biology of obesity.

Obesity has emerged as the dominant American public health problem of the 21st century. Because it stems from consuming more energy than is burned, understanding the role of appetite is central to understanding the causes of obesity. Appetite is fundamentally a biological process, based on a set of neurological signals sent from various organs and tissues to the brain; but it is also influenced by environmental and psychosocial factors. This paper outlines the biology of appetite, focusing on the multitude of hormonal and neural pathways that regulate food intake and lead to accumulation of excess body fat. It also briefly explores the effect of psychosocial and environmental factors on the brain and its signaling system, and how researchers are using this information to help control obesity.