Environment and obesity.

The aim of this review was to identify and, particularly, to classify all the numerous environmental factors that play a significant role in the environment-dependent body weight dysregulation. The main environmental obesogenic factors are related to build environment such as city plan, transport and school, inactivity, TV and screen-related immobility, smart-phone, video games; they are followed by agroalimentary factors such as imbalanced ingredients, pollutants, speed eating, portion size, sweet drinks, nibbling and junk foods supported by publicity, sociocultural and ethnic factors beside the global environmental changes and seasonal light/dark photoperiod. Beside the analytical examination of the obesogenic factors it is mentioned the cumulative effect that tends to coexist in the same population and thus magnify their pathogenic consequences. In addition, more than one obesogenic factors are present in the same population because they are the expression of another underlying common cause - poverty; such a recognition leads towards socio-economic considerations and consequently towards 'political' solutions that are beyond our scientific approach. The mechanism of action of the environmental influence includes the serotonergic system and insulin resistance. More recently, it was shown an environment dependent powerful microbiotic implication. Since obesity is influenced by genetically transmitted changes modulated by environment and lifestyle risk factors it is important to understand the genomic mechanism that allows these interactions. It was shown that obesity-predisposing gene variants that interact with environmental exposures use the DNA methylation epigenetic mechanism.