An up-to-date vision on the aetiology and on the epidemiology of obesity and morbid obesity

Abstract

Obesity is a pathological condition characterized by an excess of body fat. Both environmental and biological factors have been considered to explain the worldwide diffusion of the obese phenotype. Most likely, the abnormal accumulation of body fat can be seen as a complex interaction between the two factors. In particular, several studies have focused on the hypothalamic mechanisms controlling food intake and energy expenditure; extensive genetic investigations have demonstrated a low but appreciable percentage of obese patients bearing a single gene mutation underlying the clinical picture. Moreover, Genome-wide association studies have shown a relevant number of loci bearing Single Nucleotide Polymorphisms that increase obesity susceptibility by interacting with environmental conditions. Obesity is now considered as a social health problem since excess of fat per se or through complex metabolic activities of adipocytes may allow the development of several chronic comorbidities such as type 2 diabetes, cardiovascular disease, liver steatosis potentially evolving to cirrhosis and sleep apnea. As a consequence, obesity must be considered a serious disease leading to poor quality of life and, potentially, severe disability.