[Adipose tissue and obesity. Part 1: fat cell size and fat cell number].

The role of the number and size of adipocytes in the pathogenesis of obesity is reviewed. The observation that hyperplasia of adipose tissue is associated with child-onset obesity was over-interpreted. Nevertheless most recent studies suggest that fact cell size and number are regulated and can influence food intake. The discovery of preadipocytes has opened a new field or research offering the possibility of new concepts in the prevention and therapy of obesity.