The pathogenesis of obesity.

Obesity is an extremely challenging medical condition because it is a multifactorial disease that lies at the interface between the biology of body energy regulation and an environment (physical and sensory) that has been increasingly characterized as 'hostile to good health'. The deceptively straightforward anthropomorphic definition of obesity is the excessive accumulation of body fat. However, obesity is a chronic disease that is much more than excessive fat. It involves genetic predisposition and metabolic, hormonal and behavioural aspects and results in significant morbidity, reduced quality of life, discrimination and early mortality. The development and maintenance of obesity can be considered to result from the integration, or the accumulation, of small daily errors in energy balance over several months and years. The biological factors involved increase the predisposition toward the expansion of adipose tissue mass together with the consequences of an environment that promotes increased food intake and decreased physical activity. Multiple aetiologies may result in similar degrees of obesity.