[Advances in pathophysiological concepts of obesity]

Obesity is defined as an increase in fat mass, which reflects the inefficiency of the system regulating energy homeostasis to resist against the pressure of environmental and genetic factors. Obesity constitutes itself into several phases to reach a real pathology of adipose tissue, seat of large functional alterations. There is a continuum of obesity forms, from purely genetic forms to purely environmental forms. Within this continuum, genetic and environmental determinants interaction is the rule. The role of gut flora has become a new interesting line of research in the pathophysiology of obesity.