[Environmental factors. Opportunities and barriers for physical activity and healthy eating among children and adolescents].

While genetic factors play a role in the development of obesity, its dramatic increase in prevalence over the past few years strongly suggests an important environmental role. The results of a review on environmental opportunities and barriers for physical activity and dietary intake influencing the obesity epidemic among children and adolescents are presented. Although evidence clearly shows the impact of the environment on obesity-related lifestyle factors among children, evidence for effective strategies combating this obesogenic environment is scarce. Interventions aiming to change environmental factors to reduce childhood obesity may include providing extra sporting facilities and healthy foods/meals at school (e.g., provision of fruit), efforts to improve safety and accessibility of walking, cycling, and play areas, while at the same time attempting to influence social values attached to weight, food, or physical activity. Some level of institutionalization of systems that support the desired changes is required to sustain long-term environmental changes (e.g., ban of softdrinks at school). Better-designed and -conducted research on the true importance of environmental factors for obesogenic behavioral change is needed to achieve success of large-scale environmental change interventions.