[Obesity: epidemiology, pathophysiology and extra-respiratory complications]

Obesity is the most common nutritional disease in industrialized countries and constitutes an important public health issue. Strictly speaking, obesity is an excess of adipose tissue. In practice, body mass index (BMI)=weight (kg)/height (m)(2) is used to determine the degree of excess body weight in a patient. A BMI >=30 kg/m(2), which is associated with significantly higher morbidity and mortality, is generally used as a threshold value for obesity. Despite this measurement, obesity includes a very wide range of variable symptoms. Development of obesity is a multifactorial phenomenon implicating biological, genetic, behavioral, and environmental factors whose interaction and inter-association vary from individual to individual. There are many extra-respiratory complications of obesity which may be somatic (cardiovascular, mechanic, metabolic.), psychological, or social. Abdominal adipose tissue plays an important role in metabolic and vascular complications of obesity independently of the degree of corpulence. As an introduction, we discuss here the definitions concerned as well as the epidemiology, basic pathophysiological mechanisms, and extra-respiratory complications of adult obesity.